AN97028 TEA1110A voltage versatile transmission Application
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Application TEA1110A voltage versatile transmission circuit
AN97028
TEA1110A voltage versatile transmission
Application Note
Abstract
TEA1110A bipolar transmission circuit telephone sets. part TEA111x family. detailed description circuit blocks TEA1110A advices adjustments contained this report.
TEA1110A voltage versatile transmission
Application Note
Application TEA1110A voltage versatile transmission circuit
AN97028
Author: Gauthier Malaurie Technical Marketing, Telecom Products Caen, France
Keywords Telecom Demoboard TEA1110A Microphone DTMF Receive
Date: April 23rd, 1997
TEA1110A voltage versatile transmission
Application Note
Summary
detailed description blocks TEA1110A given. possible settings adjust transmission characteristics explained. TEA1110A incorporates microphone amplifier, DTMF amplifier receive amplifier. provides supply peripherals. evaluation board TEA1110A available.
Note: 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 licence under patent other industrial property rights.
TEA1110A voltage versatile transmission
Application Note
CONTENTS
INTRODUCTION BLOCK DIAGRAMS PINNINGS DESCRIPTION TEA1110A.10 characteristics supply block 3.1.1 characteristics 3.1.2 Supply peripherals impedance.15 Microphone amplifier.16 Receive amplifier Automatic gain control.23 DTMF amplifier "MUTE" function.27 Anti-sidetone network.28 3.8.1 TEA106x TEA111x family bridge.28 3.8.2 Wheatstone bridge APPLICATION COOKBOOK EXAMPLE APPLICATION ELECTROMAGNETIC COMPATIBILITY REFERENCES
TEA1110A voltage versatile transmission
Application Note
LIST FIGURES Fig. TEA1110A block diagram.8 Fig. TEA1110A pinning Fig. Basic application measurements Fig. characteristics configuration Fig. versus Fig. Main voltages versus line current Fig. voltage behavior line powered condition Fig. Influence resistor between SLPE Fig. Influence Rslpe characteristics Fig. Equivalent impedance Fig. Microphone channel Fig. Microphone gain versus frequency: influence temperature.18 Fig. Distortion line versus line signal (left) versus microphone signal TEA1110A Fig. Distortion line signal Iline mA.19 Fig. Microphone noise versus line current Fig. Common mode rejection ratio microphone.20 Fig. Receive channel.20 Fig. Receive gain versus Rgar connected between QR.21 Fig. Receive gain versus frequency: influence temperature Fig. Distortion versus input signal Fig. Distortion versus level with (left) loads.23 Fig. Noise Fig. microphone gain versus line current Ragc Fig. DTMF channel TEA1110A.25 Fig. DTMF gain versus frequency: influence temperature Fig. Distortion DTMF signal line versus input signal Fig. Microphone gain MUTE/ input current versus MUTE/ input voltage.27 Fig. Microphone receive gain reduction "mute" condition TEA1110A Fig. Wheatstone bridge (left) TEA106x orTEA111x family anti-sidetone bridge (right).28 Fig. Equivalent average line impedance Fig. Basic application TEA1110A.33 Fig. Component placement diagram demoboard
TEA1110A voltage versatile transmission
Application Note
INTRODUCTION
TEA1110A offers microphone, receive line interface functions required telephone sets. performs interface between line transducers handset. Furthermore, TEA1110A includes DTMF amplifier dialling. selection between microphone amplifier DTMF amplifier made with "MUTE" function. MUTE/ input switches-off both microphone receive amplifiers switches-on DTMF amplifier. report divided into parts: first part, chapter gives detailed description different circuit blocks TEA1110A including operating principles, settings transmission characteristics performances different functions; second part describes consecutive steps design adjust applications using TEA1110A introduces demoboard.
Note: values parameters given this application note accurate possible, please, refer last product specification final ones.
TEA1110A voltage versatile transmission
Application Note
BLOCK DIAGRAMS PINNINGS
Fig. shows block diagram TEA1110A, pinning shown fig.
MUTE/
current anagement
DTMF
Att.
MIC+ MICV
circuit
voltage circuit
SLPE
Fig. TEA1110A block diagram
TEA1110A voltage versatile transmission
Application Note
SLPE DTMF MUTE/
6-))
Fig. TEA1110A pinning
MIC+ MICAGC
TEA1110A
NAME SLPE DTMF MUTE/ MICMIC+
DESCRIPTION Positive line terminal Slope adjustment Line voltage regulator decoupling connected DTMF input MUTE/ input Receive amplifier input Automatic gain control Inverting microphone input inverting microphone input Negative line terminal Receive amplifier output Receive gain reduction adjustment Supply voltage speech peripherals
TEA1110A voltage versatile transmission
Application Note
DESCRIPTION TEA1110A
curves shown this section result from measurement typical samples. component names refer basic application shown fig.
+Vcc
Peripheral supply
prot
MICP
1N4004
MICM
6-))
gars
MUTE/
3.92
DTMF SLPE
DTMF
bal1
slpe
bal2
Fig. Basic application measurements
TEA1110A voltage versatile transmission
3.1.1 characteristics supply block characteristics
Application Note
Principle operation TEA1110A generates 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 apparatus, TEA1110A must have resistance current high impedance speech signals. Creg capacitor, converted into equivalent inductance (see "set impedance" section), realizes this impedance conversion from value (Rslpe) value (Rcc +Rz//Cz audio frequency range). voltage SLPE proportional line current. This general configuration shown fig.
Rline Iline
from preamp
Rexch Rgasint
Vexch
Cvcc
SLPE
Islpe Rslpe
Creg
Fig. characteristics configuration regulates line voltage between pins SLPE. voltage calculated Vref Rslpe Islpe Islpe Iline Iline line current current consumption supply current peripherals Current consumption between line current Iline flowing into apparatus determined exchange supply voltage Vexch, feeding bridge resistance Rexch, resistance telephone line Rline voltage across telephone including diode bridge.
TEA1110A voltage versatile transmission
Application Note
Below threshold line current (typically equal internal reference voltage (generating Vref) automatically adjusted lower value (down absolute minimum voltage This means that more sets operate parallel that very voltage feeding bridge line current higher value. line currents below this threshold current, TEA1110A reduced sending receiving performances. This called voltage area. internal circuitry TEA1110A supplied from VCC. line powered application, this voltage derived from line voltage means resistor (Rcc) must decoupled capacitor (Cvcc). Fig. shows current consumption (Icc) function supply voltage.
Fig. versus Fig. shows main voltages function line current.
Fig. Main voltages versus line current
TEA1110A voltage versatile transmission
Fig. shows behavior voltage area line powered condition.
Application Note
Fig. voltage behavior line powered condition
Adjustments performances reference voltage, Vref, adjusted means external resistor Rva. increased connecting resistor between pins SLPE (see fig. decreased connecting resistor between pins line powered application, recommended voltage reduction because reduces peripheral supply capability. ensure correct operation, advised adjust Vref value lower than higher than (the maximum operating voltage must guaranteed application well safe crystal operating temperature). These adjustments will slightly affect parameters: there will small change temperature coefficient Vref slight increase spread this voltage reference matching between internal external resistors. Furthermore, resistor connected between will slightly affect apparatus impedance(see section "set impedance").
TEA1110A voltage versatile transmission
Application Note
Fig. Influence resistor between SLPE slope voltage influenced Rslpe resistor shown fig. value Rslpe slightly modified even preferred changing this value will affect more than characteristics, also influences gains, characteristics, maximum output swing line voltage threshold Ith.
Fig. Influence Rslpe characteristics
TEA1110A voltage versatile transmission
3.1.2 Supply peripherals
Application Note
Principle operation supply voltage normally used supply internal circuitry TEA1110A. However, small current drawn supply peripheral circuits having ground reference. supply voltage depends current consumed peripheral circuits shown following formula: VCC0 Rccint (Irec VCC0 Irec internal current necessary supply receive output amplifier realize peak voltage accross earpiece impedance Irec Rccint internal equivalent impedance between Rccint output impedance voltage supply point. seen from fig.5, internal supply current depends voltage VCC, means that impedance internal circuitry connected between infinite. While supplying peripheral circuit VCC, supply current flowing through resistor decreases value voltage then reduces consumption. impedance combination with Irec Rccint which includes parallel impedance internal circuitry connected between VEE. line current equal equal this Rccint impedance limited minimum value ensure correct operation, will limited maximum value. limit imposed requirement maintain minimum permitted voltage between SLPE which called Vmin. maximum current available depends settings Vref, Rcc(+Rz), Rslpe required signal level line receive outputs. simplify calculation, will worst case Rccint, which Rcc, gives: Irec Vref Rslpe Iline Irec Irec VCCmin Vmin Rslpe Iline Irec Ipmax VCCmin Ipmax Vref Vmin (Rcc Rslpe Irec Rslpe
Vmin Rslpe Zline
Adjustments performances impedance connected between also determines impedance, easiest increase current capability supply point increase reference voltage Vref connecting resistor between pins SLPE (see 3.1.1).
impedance
Principle operation TEA1110A behaves like equivalent inductance that presents impedance (Rslpe) high impedance (Rp) speech signals. integrated resistance order 15.5 +/-15%. parallel with external realized Cvcc. Thus, audio frequency range, apparatus impedance
TEA1110A voltage versatile transmission
Application Note
(called impedance) mainly determined resistor. Fig. shows equivalent schematic impedance.
Creg
Rslpe
internal resistor
Rslpe
Creg
Fig. Equivalent impedance Adjustments performances When decreasing reference voltage Vref, resistor connected between parallel (see fig. slightly modifying impedance. complex impedance required, resistor replaced complex network (see fig. :Rcc Cz). resistance which influences value becomes
Microphone amplifier
Principle operation fig. block diagram microphone amplifier TEA1110A depicted.
TEA1110A voltage versatile transmission
Application Note
MIC+ MIC81
?EH?KEJ
Rgasint
Creg
SLPE
slpe
Fig. Microphone channel microphone amplifier symmetrical high input impedances (typically times between pins MIC+ MIC- with maximum tolerances 15%). input this microphone amplifier able handle signals mVrms with less than total harmonic distortion. seen from fig. microphone amplifier itself built parts: preamplifier which realizes voltage current conversion, end-amplifier which realizes current voltage conversion. overall gain (Gvtx) microphone amplifier from inputs MIC+/MIC- output given following equation: Gvtx Avtx Avtx 1.32 (Rgasint Rrefint) (Ri//Zline Rslpe) with: apparatus impedance, Rcc//Rp (typically 15.5 Rgasint internal resistor realizing current voltage conversion (typically 27.2 with spread +/-15%) Rrefint internal resistor determining current internal current stabilizer (typically with spread correlated spread Rgasint) Zline load impedance line during measurement gain control factor varying from Iline Iline when function applied (see chapter details)
TEA1110A voltage versatile transmission
Application Note
Using these typical values equation assuming Zline find gain equal Gvtx Avtx Iline
different gain controls (AGC; MUTE/) microphone preamplifier stage, modifying transconductance.
Adjustments performances shows typical frequency response gain microphone amplifier TEA1110A.
Gvtx(+75°C) 43.98 Gvtx(+25°C) 43.75 Gvtx(-25°C) 43.55
Fig. Microphone gain versus frequency: influence temperature shows distortion signal line function line signal function microphone signal
Fig. Distortion line versus line signal (left) versus microphone signal TEA1110A Fig. shows distortion line signal versus line signal line line current
TEA1110A voltage versatile transmission
Application Note
Fig. Distortion line signal Iline Fig. shows microphone noise (psophometrically weighted: curve) versus line current nominal gain when resistor connected between inputs MIC+ MIC-.
Fig. Microphone noise versus line current Fig. shows common mode rejection ratio curves present this fig. first spectrum signal when microphone signal applied MIC- while MIC+ shorted VEE, second spectrum signal when microphone signal applied pins MIC- MIC+ shorted together. Both signals kHz, difference between curves gives CMRR.
TEA1110A voltage versatile transmission
Application Note
Fig. Common mode rejection ratio microphone
Receive amplifier
Principle operation fig. block diagram receive amplifier depicted.
MUTE/
Rgarint
Vcc/2
DTMF
Att.
Fig. Receive channel
receive amplifier a-symmetrical high input impedance between pins VEE. equal with maximum tolerance +/-15%. TEA1110A able drive loads down impedance seen from fig. receive amplifier itself built parts: preamplifier which realizes
TEA1110A voltage versatile transmission
Application Note
voltage current conversion end-amplifier which realizes current voltage conversion. output capability suitable several kind earpieces drive either dynamic, magnetic piezoelectric earpieces. case magnetic dynamic earpieces, capacitor series required decoupling. overall gain Gvrx receive amplifier from input output given equation: Gvrx Avrx Avrx 1.26 Rgarint/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 (see chapter details) Using these typical values equation, find gain equal Gvrx Avrx Iline
different gain controls (AGC; MUTE/) receive preamplifier stage, modifying transconductance. Adjustments performances receive gain decreased TEA1110A connecting resistor Rgar between pins decreased from down suit application specific requirements, however, this gain adjustment slightly increases gain spread affects temperature coefficient matching between internal external resistors. receive gain compensate approximately attenuation provided antisidetone network. Fig. shows typicall curve receive gain versus external resistor Rgar. gain dependancy this external Rgar resistor given following equation: Gvrx 1.26 (Rgarint//Rgar Rrefint)
Fig. Receive gain versus Rgar connected between external capacitors Cgar (connected between Cgars (connected between VEE) ensure stability when relationship Cgars Cgar fulfilled. Cgar capacitor provides first
TEA1110A voltage versatile transmission
Application Note
order pass filter, which cut-off frequency determined with Rgarint//Rgar. Fig. shows frequency response typicall gain receive amplifier different temperatures (Cgar Cgars nF).
Gvrx(+75°C) 33.30 Gvrx(+25°C) 33.15 Gvrx(-25°C) 32.89
Fig. Receive 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. shows distortion when limitation related input voltage line current equal Fig. shows distortion signal function signal with loads line current
Fig. Distortion versus input signal
TEA1110A voltage versatile transmission
Application Note
Fig. Distortion versus level with (left) loads Fig. shows noise loaded with (psophometrically weighted: curve) function line current. This curve been done with open input With antisidetone network connected input part microphone noise generated line will added but, thanks microphone noise value, effect negligible.
Fig. Noise
Automatic gain control
Principle operation TEA1110A performs automatic line loss compensation. automatic gain control varies gain microphone receive amplifiers accordance with line current. enable this function, must connected VEE. line currents below current threshold, Istart (typically 23mA), gain control factor equal giving maximum value gains Gvtx Gvrx. this threshold current exceeded, gain control factor reduced then gains controlled microphone receive amplifiers also reduced. When line current reaches other threshold current, Istop (typically mA), gain control factor limited minimum value equal 0.5, giving lower value microphone receive controlled gains. gain control range both amplifiers typically which
TEA1110A voltage versatile transmission
Application Note
corresponds approximately line length (0.5 twisted pair copper) with attenuation dB/km. attenuation correlated current Iagc sunk AGC: when this current lower than typically gains maximum, when this current higher than typically gains minimum. This current proportional voltage between pins SLPE VEE. There internal resistor which sets Istart Istop, adding externally series (between pins VEE) reduces Iagc increases values Istart Istop. Adjustments performances TEA1110A used with different exchange supply voltages different feeding bridge resistances. this purpose, resistor Ragc, inserted between pins VEE. This Ragc resistor increases threshold currents Istart Istop. Fig. shows control microphone gain versus line current different values Ragc. When function required, must left open, then control factor equals both controlled gains their maximum values. When Ragc value Istart high, increasing value Rslpe reduces proportionally Istart shifts lower currents. this case, value Istop also reduced gains modified. value Rslpe increased lot, possible restore typical gains connecting parallel series network which makes total impedance
Fig. microphone gain versus line current Ragc
DTMF amplifier
principle operation fig.24, block diagram DTMF channel TEA1110A depicted.
TEA1110A voltage versatile transmission
Application Note
MUTE/
from receive preamp
Rgarint
Att.
VCC/2
DTMF
Att. 14.8
from microphone preamp Rgasint
Rexch
SLPE
Rslpe
Cvcc
Cexch
Fig. DTMF channel TEA1110A DTMF amplifier a-symmetrical high input impedance between pins DTMF with maximum spread +/-15%. DTMF amplifier built three parts: attenuator factor 14.8 preamplifier which realizes voltage current conversion same end-amplifier microphone amplifier. applied DTMF channel. overall gain (Gvmf) DTMF amplifier from input DTMF output given following equation: Gvmf Avmf Avmf 0.15 (Rgasint Rrefint) (Ri//Zline Rslpe) with: apparatus impedance, Rcc//Rp (typically 15.5 Rgasint internal resistor realizing current voltage conversion (typically 27.2 with spread +/-15%) Rrefint internal resistor determining current internal current stabilizer (typically with spread correlated spread Rgasint) Zline load impedance line during measurement
TEA1110A voltage versatile transmission
Application Note
Using these typical values equation assuming Zline find gain equal Gvmf Avmf Fig. shows frequency response DTMF amplifier different temperatures.
Gvmf(+75°C) 25.59 Gvmf(+25°C) 25.34 Gvmf(-25°C) 24.51
Fig. DTMF gain versus frequency: influence temperature input DTMF amplifier handle signals mVrms with less than THD. Fig. shows distortion line versus input signal Iline
Fig. Distortion DTMF signal line versus input signal
TEA1110A voltage versatile transmission
Application Note
"MUTE" function
Principle operation mute realizes electronic switching between speech mode dialling mode. level applied MUTE/ input, both microphone receive channels disabled while DTMF channel enabled. applying high level leaving MUTE/ open microphone receive channels enabled while DTMF channel disabled. MUTE/ input pull-up structure, directly driven open drain output. threshold voltage level 0.65 typically with temperature coefficient mV/°C. Fig. shows microphone gain reduction MUTE/ input current versus MUTE/ input voltage.
Fig. Microphone gain MUTE/ input current versus MUTE/ input voltage Adjustments performances Fig. shows microphone receive amplifier gain reduction Iline input signal kHz. curves present these graphics, first shows spectrum signal line when signal applied microphone inputs respectively when MUTE/ high level, second shows same signal when MUTE/ level. difference between curves this frequency gives gain reduction.
Fig. Microphone receive gain reduction "mute" condition TEA1110A
TEA1110A voltage versatile transmission
Application Note
"mute" function works down voltage equal below this threshold, microphone receive amplifiers stay always enabled independently MUTE/ input level. maximum voltage allowed MUTE/ input minimum GND-0.4
Anti-sidetone network
Principle operation avoid microphone signal come back with high level receive channel, anti-sidetone circuit uses microphone signal from SLPE (which opposite phase) cancel microphone signal input receive amplifier. anti-sidetone bridge already used TEA106x TEA111x families conventional Wheatstone bridge shown fig. used design antisidetone network.
Zbal Rslpe SLPE Rast1 Rslpe Rast3 SLPE Zbal Rast1
Zline
Zline
Rast2
Fig. Wheatstone bridge (left) TEA106x orTEA111x family anti-sidetone bridge (right) TEA106x TEA111x family anti-sidetone bridge advantage relative flat transfer function audio frequency range between input output both with real complex impedances. Furthermore, attenuation bridge receive signal (between pins independent value chosen Zbal after impedance been fixed condition shown equation fulfilled. Therefore, readjustment overall receive gain necessary many cases. Compare previous one, Wheatstone bridge advantages needing resistor less smaller capacitor Zbal. disadvantages include dependence attenuation bridge value chosen Zbal frequency dependence that attenuation. This requires some readjustment overall receive gain.
3.8.1
TEA106x TEA111x 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 scale factor chosen meet compatibility with standard value capacitor Zbal.
TEA1110A voltage versatile transmission
Application Note
practice, Zline varies strongly with line lenght line type. Consequently, value Zbal chosen with average line length giving acceptable sidetone suppression with short long lines. suppression further depends accuracy with which Zbal equals this average line impedance. Example Let's optimize theorical equivalent average line impedance shown Fig. 1265
Fig. Equivalent average line impedance compatibility capacitor value Zbal with standard capacitor value from series (220 nF): 0.636 Rast2, value 3.92 been chosen. using previous equations, calculate Zbal, Rast1, Rast3. find Rast1 Rast3 Zbal series with attenuation receive line signal between derived from following equation: Rast2 Rast1 Rast2 Rast2 Rast3 Zbal With values used this example, gives kHz. receive amplifier input impedance, typically
3.8.2
Wheatstone bridge
conditions optimum suppression given Zbal Rast1 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.
TEA1110A voltage versatile transmission
Application Note
APPLICATION COOKBOOK
this chapter, procedure making basic application given. Refering fig. design flow given number steps which should made. possible every step, components involved their influence every step given.
Step
setting
Adjustment
Adjust setting TEA1110A local requirements.
Voltage LN-VEE
This voltage adjusted changing Vref: increased with resistor between pins SLPE decreased down with resistor between LN).
slope
slope might modified changing value Rslpe (this advised: gains modified, characteristic modified).
Supply point
line powered applications, depends values Vref resistive part impedance network (Rcc Rz).
Artificial inductor
value adjusted changing value Creg: smaller value speeds-up current shape during transients decreases value inductance then affects BRL.
Impedance sidetone After setting required impedance, sidetone optimized using sidetone network order minimize loop gain line conditions. adjusted that step.
Application impedance
adjusted with impedance network connected between (Rcc Rz//Cz).
Sidetone
Adjust Zbal (Rbal1, Rbal2, Cbal) according line characteristics.
Internally defined, characteristics (Istart Istop) shiftted higher line currents with external Ragc resistor connected between VEE. case necessary shift Istart Istop lower current values, value Rslpe must increased proportionally (all gains modified).
TEA1110A voltage versatile transmission
Application Note
Step
Adjustment
TEA1110A microphone receive gains
Microphone gain
microphone gain application adjusted before entering pins MIC+/MIC- TEA1110A. reduced using resistor Rtx3 which forms bridge attenuator with Rtx1 Rtx2. Ctx1, Ctx2 form high-pass filter with Rtx1, Rtx2 series with input impedance MIC+/MIC-. capacitor Cmic forms low-pass filter with impedance microphone resistors Rmicp/Rmicm.
Receive gain
receive gain application adjusted preferably after output nevertheless, possible reduce receive gain with resistor Rgar. capacitor parallel with receive gain resistor (between TEA1110A pins GAR) form low-pass filter, stability ensured with capacitor Cgars Cgar) between pins VEE.
TEA1110A DTMF gain
DTMF
DTMF level line must adjusted before entering DTMF. selected with level MUTE/.
TEA1110A voltage versatile transmission
Application Note
EXAMPLE APPLICATION
demo board (OM5827) available. TEA1110A used various applications, this demoboard includes only TEA1110A with basic environment. Fig. gives schematic basic application TEA1110A while fig. gives component placement diagram. this schematic, capacitors connected with dotted lines resistors drawn with dotted lines indicated immunity purpose.
TEA1110A voltage versatile transmission
Application Note
Rprot
Cvcc
Rfeed
Cfeed
Rmicp Rast1
MIC+
Rtx2
Ctx2
1N4004
Rtx3
Cmic
MICP MICM
MIC-
Rtx1
Ctx1
Rmicm
6-))
Cgars
Cgar Rgar
Rear
Cear
EAR+
Ragc
MUTE Rast2
3.92
EAR-
MUTE
DTMF Rast3 Rbal1
SLPE
Rslpe
Cbal
Creg
Rbal2
Fig. Basic application TEA1110A
TEA1110A voltage versatile transmission
Application Note
Fig. Component placement diagram demoboard
TEA1110A voltage versatile transmission
Application Note
ELECTROMAGNETIC COMPATIBILITY
common international specification exists immunity, different assembly methods lead different solutions, only some advices provided. advisable take care impedance GND, smallest always best. This means that (VEE) trace must always large possible, best have second layer dedicated this purpose. MIC+/MIC- inputs also sensitive signals entering these pins would amplified). Care taken with lay-out microphone amplifier, which also helpfull noise, providing good decoupling VEE. Capacitor hundred forming low-pass filters added input amplifier. impedance capacitors parallel with electrolythic between well parallel with Creg capacitor help. Usually impedance capacitor connected between helps conducted interferences, this capacitor parallel with impedance network apparatus, value must small enough. general when connections coming from external environment (e.g. MICP, MICM, demoboard), better filter signal before influences close environment TEA1110A (e.g. action C1,C2,C6,C11 demoboard).
TEA1110A voltage versatile transmission
Application Note
REFERENCES
TEA1110A voltage versatile transmission circuit Device specification TEA1110A Line Interface Demonstration Board USER MANUAL OM5827 (report CTT96004) Philips Semiconductors SEMICONDUCTORS TELECOM SYSTEMS -IC03a/b-
TEA1110A voltage versatile transmission
Application Note
APPENDIX LIST ABBREVIATIONS DEFINITIONS
DTMF Gvmf Gvrx Gvtx Iline Irec Islpe Istart Istop MUTE/ OM5827 Rast Rexch Rgar Rgarint Rgasint Line terminals application example Automatic Gain Control: line loss compensation Balance Return Loss: matching between apparatus impedance reference Dual Tone Multi Frequency ElectroMagnetic Compatibility Receive gain adjustment TEA1110A DTMF amplifier gain Receive gain Microphone gain Integrated circuit Current consumption TEA1110A Line current Current consumption peripherals Internal current consumption (from VCC) receive amplifier Receive amplifier input TEA1110A Part line current flowing through SLPE Start current function Stop current function Threshold current voltage part Scale factor anti-sidetone network Artificial inductor voltage stabilizer MUTE/ input TEA1110A Demoboard TEA1110A Receive amplifier output TEA1110A Resistor adjust sidetone bridge attenuation Antisidetone resistor Filter capacitor equivalent inductor connection TEA1110A Bridge resistance exchange Radio Frequency Interference External resistance reduce receive gain TEA1110A Internal resistance (122 which sets receive gain Internal resistance (27.2 which sets microphone gain
TEA1110A voltage versatile transmission
SLPE MIC+/MICVCC Vref Vslpe Zbal Internal resistance between Voltage adjustment resistor Slope input TEA1110A Total Harmonic Distortion Microphone amplifier input pins TEA1110A Positive supply TEA1110A Ground reference TEA1110A voltage between Stabilized reference voltage between SLPE voltage level between SLPE Input impedance receive amplifier TEA1110A Anti-sidetone network Gain control factor
Application Note
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