AN95050 Application TEA1112 TEA1112A transmission circuits A
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Application TEA1112 TEA1112A transmission circuits
AN95050
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Abstract
TEA1112 TEA1112A bipolar transmission circuits electronic telephone sets. They added range well-known transmission circuits TEA1060-family. This report contains detailed description circuit blocks TEA1112 TEA1112A. application examples TEA1112 given. report handles consecutive steps design adjust basic application with these ICs. behaviour evaluation board with TEA1112 TEA1112A included. general notation this report both ICs, TEA1112 TEA1112A, TEA1112/A.
Philips Electronics N.V. 1995 rights reserved. Reproduction whole part prohibited without prior written consent copyright owner. information presented this document does form part quotation contract, believed accurate reliable changed without notice. liability will accepted publisher consequence use. Publication thereof does convey imply license under patent- other industrial intellectual property rights.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Application TEA1112 TEA1112A transmission circuits
AN95050
Author(s): Fernand Courtois, Communication IC's development group, Caen FRANCE. Fred Dongen, Product Concept Application Laboratory, Eindhoven Netherlands
Keywords Telecom Analog telephone Speech transmission TEA1112/A Supply
Date: November, 1995
Application TEA1112 TEA1112A transmission circuits
Summary
Application Note AN95050
This report intended provide application support designing electronic telephone sets with bipolar transmission TEA1112 TEA1112A. contains detailed description several circuit blocks both well possible settings adjust transmission characteristics. application examples TEA1112 given means descriptions, settings, measurement results performances. report handles consecutive steps design adjust basic application with TEA1112/A. evaluation board TEA1112 TEA1112A been made. results measurements shown this report. general notation this report both ICs, TEA1112 TEA1112A, TEA1112/A.
Application TEA1112 TEA1112A transmission circuits
CONTENTS
Application Note AN95050
INTRODUCTION BLOCK DIAGRAM PINNING. DESCRIPTION Supply; pins SLPE, VCC, REG. 3.1.1 TEA1112/A Supply 3.1.2 Supply peripheral circuits Impedance Supply LED; ILED Microphone amplifier; pins MIC+, MIC-, MMUTE function (TEA1112 only); MMUTE. MMUTE function (TEA1112A only); MMUTE Receiving amplifier; pins GAR, Automatic Gain Control; AGC. DTMF amplifier; DTMF 3.10 MUTE function (TEA1112 only); MUTE. 3.11 MUTE function (TEA1112A only); MUTE 3.12 Anti-sidetone circuitry 3.12.1 TEA106x family bridge 3.12.2 Wheatstone bridge
APPLICATION EXAMPLE VOLTAGE BASIC Description application Settings performance application 4.2.1 behaviour 4.2.2 Transmission 4.2.3 Dialling
APPLICATION EXAMPLE HANDSFREE Description application Settings performance application DESIGN ADJUSTMENT STEPS TEA1112/A APPLICATION IMMUNITY TEA1112 REFERENCES List abbreviations definitions
APPENDIX
Application TEA1112 TEA1112A transmission circuits
Tables figures
TABLE Fig.1 Fig.2 Fig.3 Fig.4 Fig.5 Fig.6 Fig.7 Fig.8 Fig.9 Fig.10 Fig.11 Fig.12 Fig.13 Fig.14 Fig.15 Fig.16 Fig.17 Fig.18 Fig.19 Fig.20 Fig.21 Fig.22 Fig.23 Fig.24 Fig.25 Fig.26 Fig.27 Fig.28 Fig.29 Fig.30 Fig.31 Fig.32 Fig.33 Fig.34 Fig.35 Fig.36 Fig.37 Fig.38 Fig.39 Fig.40 Fig.41 Fig.42 Fig.43 Fig.44 Fig.45
Application Note AN95050
Channel selection.
TEA1112/A Block Diagram TEA1112 pinning TEA1112A pinning Basic application used measurement Supply configuration versus Main voltages versus line current. voltage behaviour Influence resistor between SLPE VREF Influence Rslpe slope line voltage supply voltage versus consumed current Irec supply point: equivalent schematic Equivalent impedance impedance Balance Return Loss ohms reference impedance supply current versus available line current Microphone channel Microphone arrangements examples Microphone gain function Rgas resistor connected between Microphone gain versus frequency: influence temperature Distortion line function input signal microphone gains. Distortion line signal versus voltage line Noise line versus line current microphone gain. Common mode rejection ratio Microphone gain MMUTE input current Vmmute Microphone gain reduction MMUTE condition Microphone gain MMUTE input current Vmmute Microphone gain reduction MMUTE condition Receiving channel Earpieces arrangements examples. Receiving gain function Rgar resistor connected between Receiving gain versus frequency: influence temperature Distortion versus input signal Distortion receiving signal loads Noise earpiece Automatic gain control microphone amplifier DTMF channel DMTF gain versus frequency: influence temperature Distortion line function DTMF input signal different gains Microphone gain attenuation MUTE input current Vmute. Microphone gain earpiece gain reduction MUTE condition Microphone gain attenuation MUTE input current Vmute. Microphone gain earpiece gain reduction MUTE condition TEA106X family anti-sidetone bridge (left) Wheatstone bridge (right) Equivalent average line impedance Application example line interface TEA1112, discrete ringer
Application TEA1112 TEA1112A transmission circuits
Fig.46 Fig.47 Fig.48 Fig.49 Fig.50 Fig.51 Fig.52 Fig.53 Fig.54 Fig.55 Fig.56 Fig.57 Fig.58 Fig.59 Fig.60 Fig.61
Application Note AN95050
Application example dialler/ringer PCD3332-3. Line voltage across function line current Start-up after off-hook application example `real' `complex' termination Behaviour application example during pulse dialling Application example line interface TEA1112, electronic hook-switch discrete ringer Application example handsfree application TEA1093 Application example dialler/ringer PCD3332-3. Currents Isup, Iled, Ivcc function Iline Voltages VA-B, VCC, (with respect SLPE) versus Iline Maximum power into 100W, respectively loudspeaker versus Iline Circuit diagram OM4776 evaluation board with basic application TEA1112/A Components side OM4776 evaluation board Layout wiring OM4776 behaviour OM4776; conducting test behaviour OM4776; radiation test
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Application TEA1112 TEA1112A transmission circuits
INTRODUCTION
Application Note AN95050
TEA1112/A offer speech line interface functions required electronic telephone sets. They perform interface between telephone line transducers such microphone capsule(s), earpiece, loudspeaker case functions) well dialler circuit DTMF pulse dialling. Moreover, they offer hook-status indicator means output. Both have MUTE function switch between conversation dialling well MMUTE function disable microphone channel give some privacy (furthermore, this MMUTE function enables sending DTMF channel, needed some specific applications). difference between TEA1112 TEA1112A concerns MUTE MMUTE inputs. TEA1112, MUTE MMUTE functions active high level inputs; while TEA1112A, MUTE MMUTE functions active level these inputs. TABLE shows enabled channels depending levels these inputs. seen that MUTE function acts both sending receiving channels, while MMUTE function only acts sending channel.
TABLE Channel selection TEA1112 MUTE `LOW' MMUTE `LOW' Microphone DTMF Earpiece Confidence Tone TEA1112A MUTE `LOW' MMUTE `LOW' Microphone DTMF Earpiece Confidence Tone
`HIGH'
`HIGH' `LOW' `HIGH' `LOW'
`HIGH'
`HIGH'
`HIGH'
report divided into parts. first part, chapter gives detailed description different circuit blocks TEA1112/A consisting operating principles, settings transmission characteristics performances different functions. second part describes application examples TEA1112 means descriptions, settings, measurement results performances. consecutive steps design adjust basic application TEA1112/A handled. evaluation board with basic application TEA1112/A available [9]. results immunity tests this board shown this report extended with brief description board layout board wiring.
Application TEA1112 TEA1112A transmission circuits
BLOCK DIAGRAM PINNING
Application Note AN95050
block diagram TEA1112/A shown means Fig.1. pinning shown Fig.2 Fig.3.
Fig.1 TEA1112/A Block Diagram
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.2 TEA1112 pinning
Fig.3 TEA1112A pinning
Name SLPE ILED MMUTE DTMF MUTE MICMIC+
Description Positive line terminal Slope adjustment Current available drive Line voltage regulator decoupling Sending gain adjustment Microphone mute input Dual-Tone Multi Frequency input Mute input Receiving amplifier input Automatic gain control Non-inverting microphone input Inverting microphone input Negative line terminal Receiving amplifier output Receive gain adjustment Supply voltage speech peripherals
Name SLPE ILED MMUTE DTMF MUTE MICMIC+
Description Positive line terminal Slope adjustment Current available drive Line voltage regulator decoupling Sending gain adjustment Microphone mute input Dual-Tone Multi Frequency input Mute input Receiving amplifier input Automatic gain control Non-inverting microphone input Inverting microphone input Negative line terminal Receiving amplifier output Receive gain adjustment Supply voltage speech peripherals
Application TEA1112 TEA1112A transmission circuits
DESCRIPTION
Application Note AN95050
curves shown this section result from measurement typical sample. component names refer basic application shown Fig.4.
Fig.4 Basic application used measurement
3.1.1
Supply; pins SLPE, VCC, REG. TEA1112/A Supply
Principle operation
supply TEA1112/A obtained from telephone line. generate stabilized voltage (called VREF) between pins SLPE. This reference voltage, typically 3.35 temperature compensated. voltage used internal regulator generate stabilized VREF voltage decoupled capacitor Creg connected VEE. effective operation telephone set, TEA1112/A must have resistance high impedance speech signals. Creg capacitor, converted into equivalent inductance mentioned impedance section), realizes this impedance conversion from value (Rslpe) value (Rcc audio frequency range). voltage SLPE proportional line current. general supply configuration shown Fig.5
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Cvcc
Fig.5 Supply configuration
regulate line voltage voltage calculated
VREF Rslpe Islpe Islpe Iline Iled Iline: Icc: Iled: Ish: Line current Current consumption Supply current peripherals Current consumed between Supply current component Excess line current shunted SLPE (and VEE) from
line current Iline flowing into determined exchange supply voltage Vexch, feeding bridge resistance Rexch, resistance telephone line Rline voltage across including diode bridge. Below threshold line current (Ith typically equal internal reference voltage (generating VREF) automatically adjusted lower value. This means that more sets operate parallel with voltage down absolute minimum voltage excluding diode bridge. line currents below this threshold current, circuit reduced sending receiving performances. This called voltage area.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
internal circuitry TEA1112/A supplied from VCC. This supply voltage derived from line voltage means resistor (Rcc) must decoupled capacitor (Cvcc). Fig.6 shows current consumption (Icc) function supply voltage.
Fig.6 versus
Fig.7 shows main voltages function line current, while Fig.8 shows behaviour voltage area.
Fig.7 Main voltages versus line current
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.8 voltage behaviour
Adjustment
reference voltage, VREF, adjusted means external resistor Rva. increased connecting resistor between pins SLPE, decreased connecting resistor between pins However this voltage reduction possible, recommended because reduces peripheral supply capability. Fig.9 shows reference voltage, VREF, function resistor. ensure correct operation, reference voltage preferably adjusted value lower than higher than These adjustments will slightly affect parameters: there will small change temperature coefficient VREF slight increase spread this voltage reference. Furthermore, resistor connected between will slightly affect impedance (See section: `Set impedance' 3.2).
Fig.9 Influence resistor between SLPE VREF
slope voltage influenced Rslpe resistor shown Fig.10. preferred value Rslpe Changing this value will affect more than characteristics. also influences
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
microphone DTMF gains, supply current characteristic, gain control characteristics, sidetone level, maximum output swing line voltage current threshold Ith.
Fig.10 Influence Rslpe slope line voltage
3.1.2
Supply peripheral circuits
Principle operation
supply voltage normally used supply internal circuitry TEA1112/A. However, small current drawn supply peripheral circuits having ground reference. supply voltage depends current consumed peripheral circuits shown formula (See also curves Fig.11 equivalent schematic this supply point Fig.12). Rccint output impedance voltage supply point. seen from Fig.6, internal supply current depends voltage VCC; means that impedance internal circuitry connected between infinite. While supplying peripheral circuit VCC, supply current flows through resistor, decreases value voltage VCC. This voltage reduction affects consumption than voltage drop across resistor. calculate voltage drop across this resistor, both effects must taken into account. impedance combination with parallel with impedance internal circuitry connected between VEE. That what called Rccint. line current equal equal this Rccint impedance equal worst case Rccint Rcc. VCCo Rccint (Irec VCCo Irec internal current necessary supply earpiece amplifier realize peak voltage across earpiece impedance Irec Rccint fact that slightly varies with voltage VCC. worst case value Rccint Rccint (internal impedance between VEE)
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.11 supply voltage versus consumed current Irec
Fig.12 supply point: equivalent schematic
limited minimum value ensure correct functioning, will limited maximum value. limit imposed requirement maintain minimum permitted voltage between SLPE which called Vmin. maximum current available depends settings VREF, Rcc, Rslpe required signal level line receiver outputs. simplify calculation, will worst case Rccint which Rcc. gives: Irec VREF Rslpe Iline irec Irec VCCmin Vmin Rslpe Iline Irec VCCmin Ipmax -Rcc VREF Vmin Ipmax Irec Rslpe Rslpe Rslpe Vmin 1.7V Zline
Application TEA1112 TEA1112A transmission circuits
Adjustment
Application Note AN95050
impedance connected between also determines impedance, easiest increase current capability supply point increase reference voltage VREF connecting resistor between SLPE (see Fig.11). maximum preferable value VREF Adjustment section 3.1.1.
Impedance
Principle operation
behave like equivalent inductance that present impedance (Rslpe) high impedance (Rp) speech signals. integrated resistance order 15.5 15%. parallel with external filter realized Cvcc. Thus audio frequency range impedance mainly determined resistor. Fig.13 shows equivalent schematic impedance, while Fig.14 shows measurement results impedance Balance Return Loss (BRL). measures matching impedance reference impedance this case) according formula: Zset Zset
Cvcc
Fig.13 Equivalent impedance
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.14 impedance Balance Return Loss ohms reference impedance
Adjustment
When decreasing reference voltage VREF, resistor connected between parallel (See Fig.13) slightly modifying impedance. complex impedance required, resistor must replaced equivalent complex network. Keep mind that resistance this network influences voltage current supply capability. (See section 3.1.2 `Supply peripheral circuits')
Supply LED; ILED
Principle operation
TEA1112/A give on-hook off-hook status indication. This done current available drive connected between pins ILED voltage area, which corresponds line current condition, current available this LED. line currents higher than threshold, Iled starts 18mA typically, Iled current increases proportionally line current (with ratio approximately third). Iled current internally limited 19.5 (typical value). curves shown Fig.15.
Fig.15 supply current versus available line current
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
driver connected SLPE, Iled supply current will flow through Rslpe resistor. Consequently, characteristics disturbed.
Adjustment
have been designed with kind LED's long voltage across this device, current flowing through lower than VREF start stop line currents well maximum Iled current internally fixed. required, ILED output shorted SLPE avoid floating pin.
Microphone amplifier; pins MIC+, MIC-,
Principle operation
Fig.16 block diagram microphone amplifier TEA1112/A depicted.The microphone amplifier symmetrical very high input impedances. input impedance between pins MIC+ MIC- typically with maximum tolerances 15%. Thanks this high input impedance, suitable several kinds microphones: dynamic, piezoelectric electret microphones with symmetrical a-symmetrical drives (See Fig.17 some examples).
Fig.16 Microphone channel
Fig.17 Microphone arrangements examples
seen Fig.16, microphone amplifier itself built parts: pre-amplifier which realizes voltage current conversion, end-amplifier which realizes current voltage conversion.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
overall gain (Gvtx) microphone amplifier from inputs MIC+/MIC- output given following equation Gvtx Avtx asin Zline Avtx 1.31 Rrefint Rslpe with: dynamic impedance, Rcc||Rp, typically 15.5 Rgasint internal resistor realizing current voltage conversion, typically with spread +/15% Rrefint internal resistor determining current internal current stabilizer, typically with spread 15%(correlated spread Rgasint) Zline load impedance line during measurement gain control factor varying from Iline Iline when function applied; chapter 3.8. Using these typical values equation, find gain equal Gvtx Avtx Iline different gain controls (AGC, MUTE, MMUTE) microphone pre-amplifier stage, modifying transconductance.
Adjustment performance
microphone gain decreased connecting resistor Rgas between pins REG. adjusted from down suit application specific requirements. gain dependency this external resistor calculated equation shown Fig.18 typical sample. gain adjustment external Rgas resistor connected between pins slightly change gain spread.
Fig.18 Microphone gain function Rgas resistor connected between
Application TEA1112 TEA1112A transmission circuits
asin Rgas Zline Gvtx 1.31 Rrefint Rslpe
Application Note AN95050
capacitor Cgas generally connected between pins provide first order pass filter, which cut-off frequency determined product Cgas (Rgasint Rgas). Fig.19 shows frequency response microphone amplifier different temperatures (Cgas Rgasint external Rgas).
Fig.19 Microphone gain versus frequency: influence temperature
Fig.20 shows distortion signal line function microphone input signal different gains, nominal settings. inputs microphone amplifier handle signals mVrms with less than Total Harmonic Distortion (THD). overall gains (Gvtx) larger than distortion will determined output stage (clipping line signal). Fig.20 shows saturation output stage, while Fig.20 shows saturation input stage.
Fig.20 Distortion line function input signal microphone gains
Fig.21 shows distortion line signal versus voltage line line currents equal nominal gain
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.21 Distortion line signal versus voltage line
obtain optimum noise performance line, microphone inputs must loaded. Fig.22 shows noise line (psophometrically weighted; curve) function line current microphone gain with connected between microphone inputs (typical application). These curves show sensitivity noise microphone gain. noise measures -79.5 dBmp minimum send gain.
Fig.22 Noise line versus line current microphone gain
amplifier gain temperature compensated. gain adjustment external Rgas resistor connected between pins slightly change temperature coefficient; reference [2]. Fig.23 shows common mode rejection ratio nominal microphone gain. curves present this figure. first spectrum signal when sending signal applied MIC-, MIC+ being shorted decoupling capacitor. second curve spectrum signal when sending signal applied microphone inputs, MIC+ MIC- being shorted. Both signals frequency kHz. difference between curves this frequency gives CMRR.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.23 Common mode rejection ratio
MMUTE function (TEA1112 only); MMUTE
Principle operation
microphone mute function realizes electronic switching between microphone amplifier sending DTMF amplifier. This function disables microphone channel provide such kind privacy same time enables DTMF channel needed some specific applications. high level applied MMUTE input, sending DTMF channel activated, while microphone amplifier disabled. microphone amplifier enabled (depending MUTE level; TABLE either applying level typically) MMUTE input leaving open. Fig.24 shows microphone amplifier gain reduction input current function input voltage MMUTE. threshold voltage level 0.68 typically (base-emitter junction) with temperature coefficient mV/oC.
Fig.24 Microphone gain MMUTE input current Vmmute
microphone mute function effect receiving channel which fully determined MUTE level.
Performance
Fig.25 shows microphone amplifier gain reduction Iline input signal kHz. curves drawn this figure. first shows spectrum signal line speech condition when sig24
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
applied microphone inputs. second curve shows same signal DTMF condition. Both signals frequency kHz. difference between curves this frequency gives gain reduction.
Fig.25 Microphone gain reduction MMUTE condition
MMUTE function works down voltage equal 1.6V (Iline basic application). Below this threshold, microphone amplifier stays always enabled independently MMUTE input level. maximum voltage allowed MMUTE input
MMUTE function (TEA1112A only); MMUTE
Principle operation
MMUTE function realizes electronic switching between microphone amplifier sending DTMF amplifier. This function disables microphone channel provide such kind privacy same time enables DTMF channel needed some specific applications. high level applied MMUTE input, microphone amplifier activated (depending MUTE level, TABLE while DTMF channel disabled. DTMF channel enabled either applying level typically) MMUTE input leaving open. Fig.26 shows microphone amplifier gain reduction input current function input voltage MMUTE. threshold voltage level 0.68 typically (base-emitter junction) with temperature coefficient mV/oC.
Fig.26 Microphone gain MMUTE input current Vmmute
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
MMUTE function effect receiving channel which fully determined MUTE level.
Performance
Fig.27 shows microphone amplifier gain reduction Iline input signal kHz.Two curves drawn this figure. first shows spectrum signal line speech condition when signal applied microphone inputs. second curve shows same signal DTMF condition. Both signals frequency kHz. difference between curves this frequency gives gain reduction.
Fig.27 Microphone gain reduction MMUTE condition
MMUTE function works down voltage equal 1.6V (Iline basic application). Below this threshold, microphone amplifier stays always enabled independently MMUTE input level. maximum voltage allowed MMUTE input
Receiving amplifier; pins GAR,
Principle operation
Fig.28, block diagram receiving amplifier TEA1112/A depicted.
Fig.28 Receiving channel
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
receiving amplifier a-symmetrical high input impedance between pins VEE. equal with maximum tolerances 15%. suitable several kind earpieces drive either dynamic, magnetic piezo-electric earpieces (See Fig.29 some arrangements examples).
Fig.29 Earpieces arrangements examples
seen Fig.28, receiving amplifier itself built parts: pre-amplifier which realizes voltage current conversion, end-amplifier which realizes current voltage conversion. overall gain Gvrx receiving amplifier from input output given equation: Gvrx Avrx Rgarint Avrx 1.21 -Rrefint with: Rgarint internal resistor realizing current voltage conversion, typically with spread +/15% Rrefint internal resistor determining current internal current stabilizer, typically with spread (correlated spread Rgarint) gain control factor varying from Iline Iline when function applied. Using these typical values equation, find gain equal Gvrx Avrx Iline gain controls, MUTE, receiving pre-amplifier stage, modifying transconductance.
Adjustment performance
receiving gain decreased connecting resistor Rgar between pins adjusted from down suit application specific requirements. gain dependency this external resistor calculated equation shown Fig.30. gain adjustment external Rgar resistor connected between pins slightly change gain spread.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.30 Receiving gain function Rgar resistor connected between
Rgarint Rgar Gvrx 1.21 Rrefint
external capacitors Cgar (connected between Cgars (connected between VEE) ensure stability. relationship Cgars Cgar should fulfilled ensure stability. Cgar capacitor provides first order filter, which cut-off frequency determined relation Cgar (Rgarint Rgar). Fig.31 shows frequency response receiving amplifier different temperature (Cgar 100pF, Cgars nF).
Fig.31 Receiving gain versus frequency: influence temperature
maximum output swing depends line voltage, resistor, current consumption circuit, current consumption peripheral circuits load impedance receiving input handle signals mVrms with less than THD. Fig.32 shows distortion function input voltage line current equal curves correspond measurement with without function which results difference receiving gain. With AGC, gain only
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
distortion input, while without AGC, gain distortion comes from output.
Fig.32 Distortion versus input signal
maximum level increases with line current increase then limited maximum value input limitation. Fig.33 shows distortion signal function voltage Iline different loads:
Fig.33 Distortion receiving signal loads
Fig.34 shows noise loaded with (psophometrically weighted; curve) function line current. This curve been done with open input With anti-sidetone connected input, noise generated line will anti-sidetone circuitry equivalent noise input total noise generated earpiece output depends microphone amplifier gain that been set, sidetone suppression receiving amplifier gain. influence noise appears clearly Fig.34.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.34 Noise earpiece
amplifier gain temperature compensated. gain adjustment external Rgar resistor connected between pins slightly change temperature coefficient.
Automatic Gain Control;
Principle operation
TEA1112/A perform automatic line loss compensation. automatic gain control varies gain microphone receiving amplifiers accordance with line current. enable function, must connected VEE. line currents below current threshold, Istart (typical mA), gain control factor equal giving maximum value gains Gvtx Gvrx. this threshold current exceeded, gain control factor gain both controlled amplifiers decreased. When line current reaches second threshold current, Istop (typical mA), gain control factor limited minimum value equal 0.5, giving minimum value gains Gvtx Gvrx. gain control range both amplifiers typically 5.85 This corresponds line length diameter twisted pair copper cable with resistance average attenuation dB/km.
Adjustment performance
have been optimized with exchange supply voltage 48V, feeding bridge resistance times previously described line. with other configurations, resistor, Ragc, connected between pins VEE. This allows increase threshold currents Istart Istop. Fig.35 shows control microphone gain versus line current different values Ragc. function required, must open circuit. gain control applied, gain control factor stays both controlled gains have their maximum value.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.35 Automatic gain control microphone amplifier
DTMF amplifier; DTMF
Principle operation
Fig.36 block diagram DTMF channel TEA1112/A depicted.
Fig.36 DTMF channel
DTMF amplifier a-symmetrical high input impedance. impedance between DTMF typically with maximum tolerances 15%. DTMF amplifier built three parts: attenuator factor pre-amplifier which realizes voltage current conversion same end-amplifier microphone amplifier. applied DTMF channel. Fig.37 shows frequency response DTMF amplifier different temperatures (Cgas pF).
Application TEA1112 TEA1112A transmission circuits
Adjustment performance
Application Note AN95050
When resistor Rgas connected between decrease microphone gain, DTMF gain varies same way: DTMF gain 26.5 lower than microphone gain without control AGC.
Fig.37 DMTF gain versus frequency: influence temperature
input DTMF amplifier handle signals to180 mVrms with less than THD. Fig.38 shows distortion line signal versus input voltage different gains.
Fig.38 Distortion line function DTMF input signal different gains
3.10
MUTE function (TEA1112 only); MUTE
Principle operation
mute function realizes electronic switching between speech mode dialling mode. high level applied MUTE input, DTMF input enabled both microphone receiving amplifiers disabled. this mode confidence tone provided earpiece. microphone receiving amplifiers enabled either applying level typically) MUTE input leaving open; (keep mind that microphone channel depends MMUTE level; TABLE this case, DTMF input disabled.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.39 shows microphone amplifier gain reduction input current function voltage MUTE. threshold voltage 0.68 typically (base-emitter junction) with temperature coefficient
Fig.39 Microphone gain attenuation MUTE input current Vmute
Adjustment performance
Fig.40 shows microphone receiving gains reduction Iline input signal kHz.Two curves drawn each graphic. first shows spectrum signal line (QR) speech condition when signal applied microphone inputs input). second curve shows same signal DTMF condition. Both signals frequency kHz. difference between curves this frequency gives gain reduction.
Fig.40 Microphone gain earpiece gain reduction MUTE condition
MUTE function works down voltage equal 1.6V (Iline basic application). Below this threshold, microphone amplifier stays always enabled independently MUTE input level. maximum voltage allowed MUTE input 0.4V.
Application TEA1112 TEA1112A transmission circuits
3.11 MUTE function (TEA1112A only); MUTE
Application Note AN95050
Principle operation
MUTE function realizes electronic switching between speech mode dialling mode. high level applied MUTE input, microphone receiving amplifiers enabled DTMF input disabled; (keep mind that microphone channel depends MMUTE level; TABLE DTMF input enabled either applying level typically) MUTE input leaving open. this mode confidence tone provided earpiece microphone receiving amplifiers disabled. Fig.41 shows microphone amplifier gain reduction input current function voltage MUTE. threshold voltage 0.68 typically (base-emitter junction) with temperature coefficient
Fig.41 Microphone gain attenuation MUTE input current Vmute
Adjustment performance
Fig.42 shows microphone receiving gains reduction Iline input signal kHz. curves drawn each graphic. first shows spectrum signal line (QR) speech condition when signal applied microphone inputs input). second curve shows same signal DTMF condition. Both signals frequency kHz. difference between curves this frequency gives gain reduction.
Fig.42 Microphone gain earpiece gain reduction MUTE condition
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
MUTE function works down voltage equal 1.6V (Iline=2.5 basic application). Below this threshold, microphone amplifier stays always enabled independently MUTE input level. maximum voltage allowed MUTE input 0.4V.
3.12
Anti-sidetone circuitry
Principle operation
avoid reproduction microphone signals earpiece, anti-sidetone circuit uses microphone signal from SLPE cancel microphone signal input receiving amplifier. anti-sidetone bridge already used TEA106x family conventional Wheatstone bridge shown Fig.43 used basis design anti-sidetone circuit.
Fig.43 TEA106X family anti-sidetone bridge (left) Wheatstone bridge (right)
TEA106x family anti-sidetone bridge advantage relatively flat transfer function audio frequency range between pins both with real complex impedances. Furthermore, attenuation bridge received signal (between pins independent value chosen Zbal after impedance been fixed condition shown equation fulfilled. Therefore, readjustment overall receive gain necessary many cases. Wheatstone bridge advantages needing resistor fewer than TEA106x family bridge smaller capacitor Zbal. disadvantages include dependence attenuation bridge value chosen Zbal frequency dependence that attenuation. This necessitates some readjustment overall receive gain.
3.12.1
TEA106x family bridge
anti-sidetone circuit composed Rcc//Zline, Rast1, Rast2, Rast3, Rslpe Zbal. Maximum compensation obtained when following conditions fulfilled: Rslpe Rast1 (Rast2 Rast3) (Rast2 (Rast3 Rslpe)) (Rast1 Rslpe) Zbal Zline
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
scale factor chosen meet compatibility with standard capacitor from range Zbal. practice, Zline varies strongly with line length line type. Consequently value Zbal chosen with average line length giving satisfactory sidetone suppression with short long lines. suppression further depends accuracy with which Zbal equals this average line impedance.
Example
Let's optimize line length diameter copper twisted pair with average attenuation resistance capacitance approximate equivalent line impedance shown Fig.44
Fig.44 Equivalent average line impedance
compatibility capacitor value Zbal with standard capacitor from series (220nF): 140nF 0.636 220nF Rast3, value 3.92 been chosen. using previous equations, calculate Zbal, Rast1, Rast2. find Rast1= Rast2 Zbal series with (220nF//820 attenuation received line signal between derived from equation Rast2 -Rast1 Rast2 Rast2 (Rast3//Zbal). With values used example, gives kHz. receiving amplifier input impedance, typically
Application TEA1112 TEA1112A transmission circuits
3.12.2 Wheatstone bridge
Application Note AN95050
conditions optimum suppression given Rast1 Zline Zbal -Rslpe Zline Also this bridge type, value Zbal chosen that corresponds with average line length. attenuation received line signal between given Rast1 -Zbal Rast1 used adjust bridge attenuation; value influence balance bridge.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Application TEA1112 TEA1112A transmission circuits
APPLICATION EXAMPLE VOLTAGE BASIC
Application Note AN95050
application examples described this report; `low voltage basic set' this chapter `handsfree application with on-hook dialling' chapter Both examples general purpose applications exchanges with voltage regulation. Fine tuning required fulfil specific country requirements. Both applications have been build tested their functionality.
Description application
application example voltage basic telephone shown Fig.45 Fig.46. build with TEA1112 transmission discrete ringer circuit shown Fig.45, PCD3332-3 pulse/tone repertory dialler/ringer PCD3332-3 according Fig.46. interconnections between both figures indicated. application offers following features: Transmission functions with adjustable parameters described TEA1112 chapter Microphone mute function Pulse, DTMF mixed mode dialling, redial, 13-number repertory dialling specified Ringer signal detection melody generation
application build around TEA1112. individual settings TEA1112 impedance minimum supply voltage PCD3332-3 dialling. several blocks application briefly described this chapter; details concerning performances given chapter 4.2. TEA1112 this application cannot replaced TEA1112A version because inverted MUTE MMUTE (MUTE MMUTE) TEA1112A.
Polarity guard protection
diode bridge applied transmission circuit part well ringer stage ensure proper functioning independent polarity line voltage respectively rectify ringer signal. Protection achieved break-over diode between A-B/B-A terminals, current limiting components TR3, zenerdiode between transmission zener diode between PCD3332-3. current limiter provides protection against current surges exceeding designed continuous limitation line current. voltage across ringer output stage limited means zener diodes diode D12.
Interrupter
interrupter consists TR1, P-channel enhancement D-MOS BSP304A, inverter controlled DPN/FLN open drain output PCD3332-3. When handset lifted, cradle switch changes from ringer state (on-hook) transmission state (off-hook); DPN/FLN high resulting conducting TR1. Interruption line current achieved DPN/FLN level.
Speech transmission
TEA1112 stabilizes voltage between SLPE. delivers supply voltage internal PCD3332-3 diode D16. buffered while buffered C35. impedance will mainly determined impedance network between VCC. This application impedance about realised
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.45 Application example line interface TEA1112, discrete ringer
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.46 Application example dialler/ringer PCD3332-3
Application TEA1112 TEA1112A transmission circuits
Complex impedance realised means network
Application Note AN95050
application intended with dynamic microphone dynamic earpiece. electret microphone requires modification application. supply made from while gain adapted resistor which value Fig.45; application example chapter Buffer capacitor discharged heavily during break periods pulse dialing with result that buffer capacitor will charged during whole dialling digit. supply voltage increased pulse dialling applications, chapter 4.2. microphone amplifier disabled high level MMUTE input pin. this example MMUTE input coupled with output PCD3332-3. toggled `MICMUTE-key' disable enable handset microphone.
PCD3332-3 dialler/ringer
dial parameters PCD3332-3 diode options specific-country requirements. single contact keypad matrix connected with corresponding I/O's. This simple keypad offers direct access stored numbers proposed application example `STORE-key' `MRC-key' used store recall telephone numbers. Diode switch open. explained before `MICMUTE-key' applied toggle microphone amplifier during conversation means output. However, `MICMUTE-key' during ringing, toggles also ringing melody. Reset performed internal reset PCD3332-3 mainly. Reset components C36-R35 compensates spread internal reset voltage. Output DPN/FLN drives interrupter perform pulse dialling (PTS switch `closed') flash function (F/E switch `open"). position cradle switch determines level during stand-by (CSI low) conversation mode (CSI high). Input CE/FDI connected positive line wire diode-bridge detect operation mode PCD3332-3 combination with CSI. Resistor MUTE wire required prevent discharging capacitor during break-periods pulse dialling flash when reduced below voltage level MUTE high. Output TONE delivers melody ringer circuit HF/RTE high) DTMF dialling signal DTMF input TEA1112 attenuator R41-R42. PCD3332-3 open drain output which pulled-up R44.
Ringer circuit
capacitor kept charged during stand-by speed-up initialization PCD3332-3 incoming calls; `Start-up' this chapter. Supply ringer delivered ringer signal from exchange bridge series network C31-R25. When becomes high kept PCD3332-3 enters ringer mode frequencies ringer signal between (RFS switch `open') between (RFS switch `closed'). Output HF/RTE will high during ringing select ringer circuit. Volume control performed potentiometer R30. application example volume ringer sound controlled means VOL1 VOL2 outputs `VOL1/VOL2-keys'. This principle applied this example also. ringer melody changed means key-board buttons
Application TEA1112 TEA1112A transmission circuits
4.2.1 Settings performance application behaviour
Application Note AN95050
settings
voltage A-B/B-A terminals result voltage drop across TEA1112, line interrupter diode bridge. voltage drop across TEA1112 depends setting reference voltage (VREF) between SLPE voltage drop across which depends line current. Important minimum line voltage (A-B/B-A) minimum supply voltage required PCD33323. supplied which depends resistance value network between case complex impedance, total current consumption from VCC. guarantee minimum supply voltage during DTMF well pulse dialling increased enlarged reference voltage TEA1112 means between SLPE. case impedance A-B/B-A voltage measures line current minimum DTMF well pulse dialling; minimum level reached pulse dialling (long digits) when decreases below level. Fig.47 shows line voltage VA-B across A-B/B-A terminals function line current Iline nominal increased line voltage means
Supply possibilities
applied supply peripherals such PCD3332-3 electret microphone. possibilities rather limited depend general LN-SLPE setting, resistance network between total current consumption from VCC. Take account that minimum level, keep TEA1112 functioning, about line current. Furthermore, voltage difference between SLPE more than over whole line current range (!), keep send stage fully functional.
Start-up
After connecting application with line supply very first time, handset lifted charge supply capacitors. operational within line current. During on-hook capacitor kept charged R28. current this stand-by mode more than Start-up after off-hook capacitor been charged) given Fig.48 means voltage VA-B across supply voltages versus time. supplied from exchange voltage while line current during off-hook.
Application TEA1112 TEA1112A transmission circuits
10.0
Application Note AN95050
VA-B
20.0 40.0 60.0 80.0
placed
Iline (mA)
100.0
Fig.47 Line voltage across function line current
50.0
VA-B VA-B
40.0
30.0
20.0
10.0
50.0 100.0 150.0
(ms)
200.0
Fig.48 Start-up after off-hook
Application TEA1112 TEA1112A transmission circuits
4.2.2 Transmission
Application Note AN95050
impedance
impedance realised with while complex impedance network between defined. Fig.49 shows (dB) `600 set' measured with reference. same graph given (dB) `complex set' consisting measured with reference impedance case complex impedance value capacitor increased meet requirements. this example, value eliminate influence transducers handset, they have been replaced resistors during measurement. line current
40.0
(dB)
35.0
30.0
Zset
25.0
20.0
Zset 220+825//115nF,
15.0
10.0
100.0 1.0k
(Hz)
5.0k
Fig.49 application example `real' `complex' termination
Send receive
This application intended with dynamic microphone. total gain from microphone terminals line measures 50dB impedance line load without function. internal setting TEA1112 typical, while about lost components (both series with inputs, termination resistor across inputs. send gain TEA1112 decreased minimum 39dB according [2]. overall send gain results with maximum swing line signal measures over frequency range 3400 impedance, line load line current. Capacitor between gate-source keeps conducting negative swings line signal; improves maximum swing line signal lower frequencies.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
overall receive gain from line earpiece about -2.5 earpiece impedance This attenuation from line input, internally determined gain receive stage typically attenuation component gain values given without activated function. receive gain reduced from minimum means resistor R13. receive gain reduced which result overall receive gain -8.5 typically. Send receive gains internally defined on-chip resistors. Reduction these gains external resistors (R4, R13) result matching inaccuracies.
Side tone
Reproduction (electrical) microphone signal earpiece reduced anti-sidetone circuit consisting components Zbal with principle applied TEA1060-family bridge given chapter 3.12 fully described [8]. case applied (pin open) anti-sidetone circuit re-calculated mean cable length Readjustment balance circuit necessary other cable types, different line length, etc.
4.2.3
Dialling
DTMF dialling
DTMF signal from TONE output PCD3332-3 attenuated network applied DTMF input TEA1112. Resistor parallel input impedance DTMF amplifier typ.). During dialling, MUTE high, signal amplified DTMF stage transferred line resulting total level impedance line load. gain DTMF stage 25.5 typical. reduction microphone gain means external resistor reduces also DTMF gain transmitted signal levels. attenuation network R41-R42 redefined correct reduced signal transfer. Take account that decreases during DTMF dialling because enlarged current consumption PCD3332-3 this mode.
Pulse dialling Flash
line current will interrupted electronic interrupter (TR1) under control DPN/FLN signal. During progress dialled digit flash) PCD3332-3 supplied stored energy because level charge-up this capacitor. value buffer capacitor value keep supply level >2.5 Fig.50 shows voltage A-B/B-A terminals, supply voltages line current during dialling `zero' Vexchange line current. voltage reduced about dialling phase test result this application example. Take into account that could worst case conditions. selectable maximum FLASH time PCD3332-3 flash-times voltage remains 2.5V.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
VA-B
50.0 25.0
Iline
30.0m 20.0m 10.0m 500.0m
Fig.50 Behaviour application example during pulse dialling
Application TEA1112 TEA1112A transmission circuits
APPLICATION EXAMPLE HANDSFREE Description application
Application Note AN95050
circuit diagram handsfree application split-up three figures. consists electronic hook switch, TEA1112 transmission discrete ringer circuit shown Fig.51, TEA1093 handsfree application Fig.52 PCD3332-3 pulse/tone repertory dialler/ringer according Fig.53. Interconnections between Fig.51 Fig.52 indicated means net-in/net-out symbols while interconnections between Fig.51 Fig.53 given offpage-symbols. application offers: Pulse, DTMF mixed mode dialling, redial, 13-number repertory dialling with PCD3332-3 Transmission functions with adjustable settings described TEA1112; chapter Handset operation Handsfree operation Ringer signal detection, melody generation volume control.
Line connection electronic hook switch interrupter
transmission circuitry ringer stage connected with line separate diode bridges ensure proper functioning application independent polarity line voltage rectify ringer signal. zener-diodes series with ringer bridge reduce line-load from ringer stage during transmission. application protected against over-voltages line input break-over diode D18. Components limit current through when line current exceeds about 150mA. This current limiter designed continuous limitation line current. only provides protection against current surges. electronic hook-switch interrupter controlled inverter DPN/FLN open drain output PCD3332-3. During off-hook when handset lifted, when `HOOK-key' activated, DPN/FLN high resulting conducting TR1. Conducting initiated high ohmic resistor taken over R24. Interruption line current achieved DPN/FLN low. When application connected with line supply very first time, electronic hook-switch switchedon short time resulting quick charge-up supply capacitors VDD. During stand-by capacitor kept charged means R28.
Handset Handsfree application
handsfree circuit TEA1093 connected between positive line wire, which connected TEA1112 R12, SLPE TEA1112. current into TEA1112 have most line current available loudspeaker function TEA1093. Resistor keeps TEA1093 operational saturation line signal large negative amplitudes. base microphone (HF-mic) handset microphone (HS-mic) switched input TEA1093 means respectively depending HF/RTE level PCD3332-3. Handsfree switched-on when HF/RTE high resulting transfer HF-mic signal transmit input TEA1093 (MIC). Handset mode achieved HF/RTE low; HS-mic operational while TEA1093 forced into transmit mode level MUTER generated TR9. Transmit receive state under control duplex controller TEA1093. discrete switching circuitry microphones could replaced 74HC4053 multiplexer/demultiplexer applied [7].
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
transmit output signal between MOUT MICGND mode) transferred inputs TEA1112 attenuator R42, R15. signal between inputs amplified line. receive signal transferred output TEA1112 offered earpiece RIN1 TEA1093. RIN2 connected which ground reference receive signal TEA1112. signal between RIN1 RIN2 amplified means loudspeaker amplifier supplied loudspeaker. Volume control performed simple potentiometer R41. Transmit receive gains transmit receive channels TEA1093 TEA1112 conformity with sensitivities applied microphones, earpiece loudspeaker; `Settings performances application'; chapter 5.2. TEA1112 described chapter this report while settings duplex controller TEA1093 according Application Note TEA1093 demonstration model TEA1093 [4].
PCD3332-3 dialler/ringer
single contact matrix keypad connected with corresponding I/O's. keypad includes memory keys, direct access stored numbers case diode switch closed. PCD3332-3 output DPN/FLN drives electronic hook-switch perform pulse dialling flash function (F/E diode option applied). Reset performed internal reset PCD3332-3 mainly. Reset components C71-R71 compensates spread internal reset voltage. Input CE/FDI connected positive line wire ringer bridge detect operation mode PCD3332-3 combination with CSI. Series diode positive line wire applied fast trailing edge pulse after on-hook line breaks. Output MUTE wired TEA1112 TEA1093 D20. This diode prevents levels MUTET below reference TEA1093. Output TONE delivers melody ringer circuit HF/RTE high) DTMF dialling signal DTMF input TEA1112 attenuator R41-R42. different modes PCD3332-3 are: Stand-by mode: HF/RTE during specific time. stand-by mode left when goes high. changes over ringer mode when incoming ringer signal detected, changes over handset mode when goes high comes on-hook dialling handsfree mode when `HOOK-key' activated. Ringer mode: high, resulting HF/RTE high. ringer mode left when goes time (stand-by mode), when handset lifted (handset mode) when `HOOK-key' pressed (handsfree mode). Handset mode: high, high resulting HF/RTE low. handset mode left when handset back cradle (stand-by mode) when `HOOK-key' pressed while handset back (handsfree mode). Handsfree mode: HF/RTE high, low. This mode entered pressing `HOOK-key'. handsfree mode left pressing `HOOK-key' (stand-by mode) lifting handset (handset mode). Dialling operations possible handset handsfree mode. Pulse DTMF dialling selected diode switch [1].
Ringer circuit
discrete ringer stage from example extended this application with volume control keypad PCD3332-3 outputs VOL1 VOL2. sound pressure from (Murata PKM34EW-1224) changed steps. Maximum volume obtained when both VOL1 VOL2 low.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.51 Application example line interface TEA1112, electronic hook-switch discrete ringer
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.52 Application example handsfree application TEA1093
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
this page left blank intentionally
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.53 Application example dialler/ringer PCD3332-3
Application TEA1112 TEA1112A transmission circuits
Settings performance application
Application Note AN95050
settings
stabilized voltage TEA1112 (VREF between SLPE) increased means (100 adjust voltage difference between TEA1093 600mV. voltage A-B/B-A line terminals measures slope Vline/Iline characteristic about R20, channel-resistance TR1. stabilized voltage (TEA1093) adjusted [3]. Take into account that VSUP-VBB least maintain maximum efficiency current switch TEA1093 mean speech levels. line current split-up Isup flowing into TEA1093 supply internal circuitry including loudspeaker amplifier microphones Iled through which function line current. Refer chapter flowing into TEA1112; realised (VSUP-VSREF)/R11 0.32/100 typical Ivcc which includes current consumption TEA1112, chapter 3.1, current consumption PCD3332-3 conversation mode
Fig.54 shows these currents function Iline conversation mode while Fig.55 gives line voltage VA-B, supply voltages both with respect VEE, stabilized voltage with respect SLPE versus Iline.
80.0
Isup Iled (mA)
70.0
Ivcc (mA)
60.0
50.0
40.0
Ivcc
30.0
20.0
Isup
10.0
Iled
500.0m
10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0
Iline (mA)
Fig.54 Currents Isup, Iled, Ivcc function Iline
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
11.0
VA-B
10.0
VA-B
10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0
VDDV
Iline (mA)
Fig.55 Voltages VA-B, VCC, (with respect SLPE) versus Iline
line current, current into measures 13.8 from which (typ) consumed internal circuitry TEA1093 250µ external circuitry connected VBB. remaining supply current generate loudspeaker signal line current) thus about which gives maximum output power 15.8 theoretically into loudspeaker. Measured 12.5 also Fig.56.
Transmission
Transmit receive gains conformity with sensitivities proposed microphones, earpiece loudspeaker performance application used handset handsfree set. applied handset (Ericsson RLGN40201/8B6) contains electret microphone with sensitivity -44.5 dBV/Pa kHz, load) dynamic earpiece dBPa/V. base contains microphone with sensitivity dBV/Pa kHz, load) loudspeaker (Philips type AD2071/Z50). overall transmit gain, line load, from line measures result gain from R57) MOUT, attenuation from MOUT inputs TEA1112 gain from inputs line. default microphone gain TEA1112 reduced means (47.5 receive gain from line earpiece -6.5 from line loudspeaker about receive gain TEA1112 application reduced from default -4.5 means (200 Volume control achieved potentiometer R41. proposal volume control PCD3332-3 found [3], while circuit realisation offered [6].
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
more than 3400 complex impedance same reference impedance while measured without handset. least complex impedances impedance meet requirements. Fig.56 shows maximum power generated into loudspeaker respectively function available line current, with without connected LED. nominal supply voltage measures 3.55 `rising edges' curves power limited available supply current. power `flat area' curves limited supply voltage VBB. power this area increased enlarged voltage (VBB 3.55 means resistor between TEA1093 [3]. Adjust this case also voltage SUP, means minimum level between VBB. current consumed LED, Fig.54, available handsfree loudspeaker function; reduces maximum power loudspeaker lower line currents, shown Fig.56.
45.0 40.0 35.0
Pout (mW)
30.0 25.0
20.0 15.0 10.0
10.0
without supplied
20.0 30.0 25.0 35.0
3.55
40.0
15.0
Iline (mA)
45.0
Fig.56 Maximum power into 100, respectively loudspeaker versus Iline
Dialling
DTMF: signal from TONE output attenuated (12.5 amplified TEA1112 (17.5 DTMF level -6.5 line load. Pulse dialling: line voltage this application been increased create voltage space between TEA1093. This results back-up level more than during pulse dialling flash times (maximum selectable flash time).
Application TEA1112 TEA1112A transmission circuits
DESIGN ADJUSTMENT STEPS TEA1112/A APPLICATION
Application Note AN95050
This chapter gives number adjustment steps which should made design adjust basic application TEA1112/A. every `Adjustment' `Components' given. influence characteristics application considerations which have taken into account added `Remarks'. components refer circuit diagram Fig.57 which application evaluation board OM4776 described chapter Adjustment impedance Component(s) Remark(s) Zset depends mainly network R1//C1) frequencies from 3400 series with supply depends resistance depends `Set impedance' with respect reference impedance (PTT requirement). Value (depends values resistor between applied) important lower frequencies (300 Hz). Adapt improve necessary. Value also influence start-up time!
(Z1),
Side tone
Zbal (R8+R10//C4), Depends cable type, mean cable length, function Zset best choice. Modification means also adaption Leq, VLN, voltage threshold current, microphone gain, function side tone balancing. Refer local requirements. Increases supply possibilities. Reduces Leq; reduces lower frequencies; BRL. Reduces supply voltage level; take account minimum operating level minimum permitted voltage space between SLPE (1.6 supply level depends VLN, resistance network (Z1) between current consumption from VCC. Take account minimum operating level minimum voltage space between SLPE. Internally defined when connected VEE. Adjustable increase `start stop' currents relation with Vexch Rexch. chapter 3.8. function disabled leaving open.
slope
(R9)
increase
(REG-SLPE)
decrease
R(LN-REG)
supply
(Z1),
Application TEA1112 TEA1112A transmission circuits
Microphone gain
Application Note AN95050
Internally defined internal resistance Rgasint. reduced matching with Rgasint. Take into account attenuation from capsule inputs with respect parallel with Zmic typ). Value couple capacitors microphone with respect input impedance external microphone network.
High pass
pass Supply DTMF gain
Value combination with R4//Rgasint. Electret microphone supplied from extra filter DTMF gain microphone gain 26.5 Total DTMF gain means attenuation network between DTMF generator TEA1112/A DTMF input.
Receive gain
Internally defined (from internal resistance Rgarint. reduced R13. matching with Rgarint. Take into account attenuation from output earpiece R14. Overall receive gain from line earpiece depends attenuation from line input. combination with earpiece impedance. combination with source impedance typ).
High pass pass Stability
Value combination with R13//Rgarint
MUTE
TEA1112
MUTE active high. MUTE from dialler high during dialling. Apply series resistance MUTE wire from dialler TEA1112 (ca. prevent discharge capacitor during break periods pulse dialling flash) MUTE high. MUTE active low. MUTE from dialler during dialing. Current consumed available added application. ILED-pin connected with SLPE when function used.
MUTE
TEA1112A
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
components
placed: mounted demonstrate TEA1113
Fig.57 Circuit diagram OM4776 evaluation board with basic application TEA1112/A
Application TEA1112 TEA1112A transmission circuits
IMMUNITY TEA1112
Application Note AN95050
TEA1112 TEA1112A have been designed with on-chip measures keep disturbances away from sensitive circuit parts higher frequencies MHz). lower frequency range (from 150kHz upwards) coupling into occurs mainly A/B-lines handset cord. Improvement immunity those frequencies realised filtering connectors pins layout which designed with respect EMC. evaluation board OM4776 been made TEA1112/A with basic application according Fig.57. components side shown Fig.58 board layout Fig.59. dimensions board provided with connection terminals edge jumpers (J3, define state logic inputs TEA1112 well TEA1112A. Jumpers function respectively. Some components mounted soldering pins simplify modification application. Components placed while intended board with TEA1113. TEA1113 described this report; refer [10]. Fig.57 components values. OM4776 single-sided wiring with filled ground plane between interconnections. measures are: Filtering from A-B/B-A terminals line input TEA1112/A means line terminals, from VEE. Filtering from terminals MIC-/MIC+ inputs terminals, series resistors decoupling pins means C17. bandwidth microphone amplifier limited Filtering receiver channel input from output earpiece terminals means C19. Furthermore bandwidth receiver amplifier limited stability guaranteed means combination Decoupling means C15.
General recommendations measures design are: filled ground between wires case single-sided ground plane when double-sided applied. Place line handset connectors close each other same side decouple connections means capacitors. Place capacitors close possible corresponding pins. small size ceramic capacitors. Make interconnection-wires short possible. wire-bridges instead clever design with long wires. Design symmetrical microphone entry from connector inputs
Test method results
immunity test split test methods. conducting test [11], frequency range MHz, carried with disturbance signal coupled into A-B/B-A cable coupling/decoupling networks. signal with amplitude modulated with signal sinewave modulation depth.The results measurements given Fig.60 means detected levels lines receiver output with respect Vrms dBV) reference level.
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
Fig.58 Components side OM4776 evaluation board
Fig.59 Layout wiring OM4776
Application TEA1112 TEA1112A transmission circuits
-60.0
Application Note AN95050
detected level (dBV)
-70.0
A-B/B-A terminals
-80.0
-90.0
-100.0
earpiece
-110.0 100.0k 1.0M 10.0M
(Hz)
200.0M 100.0M
Fig.60 behaviour OM4776; conducting test
-60.0
detected level (dBV)
-70.0
A-B/B-A terminals
-80.0
-90.0
-100.0
earpiece
-110.0 80.0M 100.0M
(Hz)
Fig.61 behaviour OM4776; radiation test
1.0G
Application TEA1112 TEA1112A transmission circuits
Application Note AN95050
second test [12] OM4776 carried electro-magnetic field. field strength over frequency range while signal modulated with signal modulation depth. results measurements shown Fig.61 means detected levels lines receiver output with respect Vrms dBV) reference level. OM4776 evaluation board meets requirements according [11] [12]. detected signal levels, result measurements, both cases less than demands. Note: logic inputs MUTE, MMUTE (TEA1112) MUTE, MMUTE (TEA1112A) sensitive because rather internal pull-down currents. When they used connect them VEE, case TEA1112, VCC, case TEA1112A.
Application TEA1112 TEA1112A transmission circuits
[10] [11] [12]
Application Note AN95050
REFERENCES
Philips Semiconductors DATA DHEET PCD3332-3 Multi-standard pulse/tone repertory dialler/ringer. Philips Semiconductors Tentative Device Specification TEA1112 TEA1112A. voltage versatile telephone transmission circuits with dialler interface. Philips Semiconductors Application Note ETT/AN93015. `Application TEA1093 handsfree circuit', C.H.Voorwinden K.Wortel. Philips Semiconductors Application Note ETT/AN94001. `User Manual OM4750: Demonstration board TEA1093 TEA1094', R.v.Leeuwen C.Voorwinden. DATA HANDBOOK IC03 `Semiconductors Telecom Systems'. Philips Semiconductors Application Note ETT/AN94002. `Design considerations high_end telephone with PCA1070, TEA1093 PCD335X', K.Wortel. Philips Semiconductors Application Note ETT95007. `OM4757 Demonstration Board PCD3332-3/ TEA1064B-1062/TEA1093-1094', F.v.Dongen. Philips Components Laboratory Report ETT89009. `Application versatile speech/transmission circuit TEA1064 full electronic telephone sets', F.v.Dongen P.J.M.Sijbers. Philips Semiconductors User Manual ETT/UM95011. `Evaluation board TEA1112/A TEA1113', E.Bosma. Philips Semiconductors Tentative Device Specification TEA1113. voltage versatile telephone transmission circuit with dialler interface. Publication 1000-4-6 (formerly 801-6). Electromagnetic compatibility electrical electronic equipment. Part6: Immunity conducted disturbances, induced radio frequency fields above kHz. 1000-4-3 Draft International Standard (Annex Immunity radiated, radio frequency, electromagnetic fields (formerly 801-3).
Application TEA1112 TEA1112A transmission circuits
APPENDIX
A-B/B-A CE/FDI DIODE DPN/FLN DTMF Electret GNDMIC Gvrx Gvtx HC4053 HF-mic HF/RTE HOOK HS-mic ICC, Iled Iline Irec Istart, Istop
Application Note AN95050
List abbreviations definitions
Line terminals application examples Automatic Gain Control; line loss compensation facility Access Pause Time selection PCD3332-3 Balance Return Loss Chip Enable Frequency Discriminator Input PCD3332-3 Column keyboard input PCD3332-3 Cradle switch input PCD3332-3 Diode option input PCD3332-3 DTMF output selection PCD3332-3 (Inverted) Dial Pulse FLash output PCD3332-3 Dual Tone Multi Frequency Electro Magnetic Compatibility Electret microphone with amplifier Flash Earth selection PCD3332-3 Ground reference TEA1093 Ground reference microphone amplifier TEA1093 Gain factor receive stage TEA1112/A Gain factor transmit stage TEA1112/A Philips with 2-channel analogue switches Handsfree Handsfree microphone Handsfree Ringer Tone Enable output PCD3332-3 HOOK-key PCD3332-3 High Pass Handset microphone Current consumption TEA1112/A (from VCC) Current through connected between ILED Line current Current consumption peripheral devices connected Internal current consumption (from VCC) receiver amplifier TEA1112/A Excess line current from SLPE Start stop currents function Threshold current voltage function Current transmission circuit application Scale factor balance network Light Emitting Diode Enable output PCD3332-3 Listening-in Artificial inductor voltage stabilizer TEA1112/A; Mark Space ratio selection PCD3332-3
Application TEA1112 TEA1112A transmission circuits
M0-M9 MOUT MUTE MUTER MUTET OM4776 PCD3332-3 Power Down/PD Rast RESET RINn Rexch Rgarint Rgar Rgasint Rgas SREF STORE TEA1093 TEA1112 TEA1112A TEA1112/A TEA1113 TONE VA-B Memory location keys PCD3332-3 Microphone input TEA1093 Memory Location Access selection PCD3332-3 Microphone amplifier output TEA1093 Memory Recall-key PCD3332-3 MUTE output PCD3332-3 MUTE input TEA1112 Receive channel MUTE input TEA1093 Transmit channel MUTE input TEA1093 Evaluation board TEA1112/A Printed Circuit Board Multi standard pulse/tone repertory dialler/ringer Pulse Tone Selection PCD3332-3 Piezo Ceramic Buzzer Element Reduced current consumption mode during pulse dialling flash Resistor adjust sidetone bridge attenuation Anti sidetone resistor Reset input PCD3332-3 Radio Frequency Ringer Frequency Selection PCD3332-3 Receiver amplifier inputs TEA1093 keyboard input PCD3332-3 Bridge resistance exchange Internal resistance (100 define receive gain TEA1112/A External resistance reduce receive gain TEA1112/A Internal resistance define microphone gain TEA1112/A External resistance reduce microphone gain TEA1112/A Internal resistance TEA1112/A between Supply reference input TEA1093 Store-key programming mode PCD3332-3 Supply input TEA1093 Handsfree Transmission MUTE MMUTE active high Transmission MUTE MMUTE active General notation TEA1112 well TEA1112A Transmission TEA111X-family with dynamic limiter Total Harmonic Distortion Tone generator output PCD3332-3 Voltage across A-B/B-A line terminals Supply output TEA1093 Supply supply voltage TEA1112/A Positive supply PCD3332-3 Ground reference TEA1112/A
Application Note AN95050
Application TEA1112 TEA1112A transmission circuits
VOLn VREF VSLPE Vexch XTALn Zmic Zbal Zset
Application Note AN95050
level TEA1112/A (with respect VEE) Receiver volume adjustment TEA1093 Volume control outputs PCD3332-3 Stabilized reference voltage between SLPE TEA1112/A level SLPE TEA1112/A, level TEA1093 application Negative Supply PCD3332-3 Exchange voltage Oscillator inputs PCD3332-3 Input impedance receive amplifier TEA1112/A Symmetrical Input impedance microphone amplifier TEA1112/A Complex network between TEA1112/A Balance network reduce side tone impedance between A-B/B-A terminals Gain control factor function; Reference REFERENCE chapter Reference equation
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