AN96071 TEA1118/A versatile cordless transmission Applicatio

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AN96071 TEA1118/A versatile cordless transmission Applicatio

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Application TEA1118 TEA1118A versatile cordless transmission circuits
AN96071
TEA1118/A versatile cordless transmission
Application Note
Abstract
TEA1118 TEA1118A bipolar transmission circuits cordless telephone sets answering machines. They part TEA111x family. detailed description circuit blocks TEA1118 TEA1118A advices adjustments contained this report.
TEA1118/A versatile cordless transmission
Application Note
Application TEA1118 TEA1118A versatile cordless transmission circuits
AN96071
Author: Malaurie Technical Marketing, Telecom Products Caen, France
Keywords Telecom Demonstration Board TEA1118 TEA1118A Transmit DTMF Receive
Date: July 31st, 1996
TEA1118/A versatile cordless transmission
Application Note
Summary
detailed description blocks both TEA1118 TEA1118A given. possible settings adjust transmission characteristics explained. TEA1118 TEA1118A incorporate transmit amplifier receive amplifier, TEA1118A incorporates also DTMF amplifier. evaluation board TEA1118A, which used TEA1118, available. general notation this report both TEA1118/A.
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.
TEA1118/A versatile cordless transmission
Application Note
CONTENTS
INTRODUCTION BLOCK DIAGRAMS PINNINGS DESCRIPTION TEA1118/A.12 characteristics supply block 3.1.1 characteristics 3.1.2 Supply peripherals impedance.17 Transmit amplifier TMUTE function (TEA1118A only) Receive amplifier Automatic gain control.26 DTMF amplifier (TEA1118A only).27 MUTE function (TEA1118A only) Anti-sidetone network.31 3.9.1 TEA106x TEA111x family bridge.31 3.9.2 Wheatstone bridge APPLICATION COOKBOOK EXAMPLE APPLICATION ELECTROMAGNETIC COMPATIBILITY REFERENCES
TEA1118/A versatile cordless transmission
Application Note
LIST FIGURES FIG. TEA1118 BLOCK DIAGRAM FIG. TEA1118A BLOCK DIAGRAM FIG. TEA1118 PINNINGS.10 FIG. TEA1118A PINNINGS.11 FIG. BASIC APPLICATION MEASUREMENTS FIG. CHARACTERISTICS CONFIGURATION FIG. VERSUS VCC.14 FIG. MAIN VOLTAGES VERSUS LINE CURRENT FIG. VOLTAGE BEHAVIOR LINE POWERED CONDITIONS FIG. VOLTAGE BEHAVIOR WITH EXTERNAL POWER SUPPLY.15 FIG. INFLUENCE RESISTOR BETWEEN SLPE 15MA FIG. INFLUENCE RSLPE CHARACTERISTICS FIG. EQUIVALENT IMPEDANCE FIG. TRANSMIT CHANNEL FIG. TRANSMIT GAIN VERSUS RGAT CONNECTED BETWEEN FIG. TRANSMIT GAIN VERSUS FREQUENCY: INFLUENCE TEMPERATURE.19 FIG. DISTORTION LINE VERSUS TRANSMIT SIGNAL NOMINAL GAIN TEA1118/A FIG. DISTORTION LINE VERSUS TRANSMIT SIGNAL GAIN TEA1118.20 FIG. DISTORTION LINE SIGNAL ILINE WITH EXTERNAL POWER SUPPLY FIG. TRANSMIT NOISE VERSUS LINE CURRENT FIG. COMMUN MODE REJECTION RATIO TRANSMIT FIG. TRANSMIT GAIN TMUTE INPUT CURRENT VERSUS TMUTE INPUT VOLTAGE FIG. TRANSMIT GAIN REDUCTION TMUTE CONDITION FIG. RECEIVE CHANNEL.23 FIG. RECEIVE GAIN VERSUS RGAR CONNECTED BETWEEN FIG. RECEIVE GAIN VERSUS FREQUENCY TEMPERATURE FIG. DISTORTION VERSUS INPUT SIGNAL FIG. DISTORTION VERSUS LEVEL WITH LOAD.26 FIG. NOISE FIG. TRANSMIT GAIN VERSUS LINE CURRENT RAGC.27 FIG. DTMF CHANNEL TEA1118A FIG. DTMF GAIN VERSUS FREQUENCY DIFFERENT TEMPERATURES FIG. DISTORTION DTMF SIGNAL LINE VERSUS INPUT SIGNAL FIG. TRANSMIT GAIN MUTE INPUT CURRENT VERSUS MUTE INPUT VOLTAGE.30 FIG. TRANSMIT RECEIVE GAIN REDUCTION MUTE CONDITION TEA1118A.30 FIG. TEA106X ORTEA111X FAMILY ANTI-SIDETONE BRIDGE (LEFT) WHEATSTONE BRIDGE (RIGHT) FIG. EQUIVALENT AVERAGE LINE IMPEDANCE FIG. BASIC APPLICATION TEA1118A
TEA1118/A versatile cordless transmission
Application Note
INTRODUCTION
TEA1118/A offer transmit, receive line interface functions required cordless telephone sets answering machines. They perform interface between line interface cordless telephone between line codecs digital answering machine. Furthermore, TEA1118A includes DTMF amplifier dialling. selection between transmit amplifier DTMF amplifier made with MUTE TMUTE function. MUTE function switches-off both transmit receive amplifiers while TMUTE switches-off only transmit amplifier, both switch-on DTMF amplifier. TEA1118 mainly dedicated applications where DTMF necessary (eg: answering machine application) where DTMF provided some other part (eg: DECT application). TEA1118A mainly dedicated base stations. report divided into parts: first part, chapter gives detailed description different circuit blocks TEA1118/A including operating principles, settings transmission characteristics performances different functions; second part describes consecutive steps design adjust applications using TEA1118/A introduces demoboard.
Note: values parameters given this application note accurate possible, please, refer last product specification final ones.
TEA1118/A versatile cordless transmission
Application Note
BLOCK DIAGRAMS PINNINGS
Fig. shows block diagram TEA1118, fig. shows block diagram TEA1118A, pinnings shown fig.
current management
circuit
voltage circuit
SLPE
Fig. TEA1118 block diagram
TEA1118/A versatile cordless transmission
Application Note
MUTE
current management
DTMF
Att.
TMUTE Transmit mute
circuit
voltage circuit
SLPE
Fig. TEA1118A block diagram
TEA1118/A versatile cordless transmission
Application Note
SLPE
TEA1118M
TXAGC
SLPE
TEA1118T
TXAGC
Fig. TEA1118 pinnings TEA1118M TEA1118T NAME SLPE TXTX+ DESCRIPTION Positive line terminal Slope adjustment Line voltage regulator decoupling Transmit gain reduction adjustment connected connected connected connected Receive amplifier input Automatic gain control Inverting transmit input inverting transmit input Negative line terminal Receive amplifier output Receive gain reduction adjustment Supply voltage speech peripherals
TEA1118/A versatile cordless transmission
Application Note
SLPE TMUTE DTMF MUTE
TEA1118AM
TXAGC
SLPE TMUTE DTMF MUTE
TEA1118AT
TXAGC
Fig. TEA1118A pinnings TEA1118AM TEA1118AT NAME SLPE TMUTE DTMF MUTE TXTX+ DESCRIPTION Positive line terminal Slope adjustment Line voltage regulator decoupling connected Transmit mute input Dual-tone multifrequency input connected Mute input Receive amplifier input Automatic gain control Inverting transmit input inverting transmit input Negative line terminal Receive amplifier output Receive gain reduction adjustment Supply voltage speech peripherals
TEA1118/A versatile cordless transmission
Application Note
DESCRIPTION TEA1118/A
curves shown this section result from measurement typical samples. component names refer basic application shown fig.
+Vcc
Peripheral supply
Cvcc
Rprot
Rast1
Rtx2 Rtx1
Ctx1
1N4004
Rtx3
Ctx2
TEA1118/A
Cgar
Cgars
Rgar Cear
Ragc
MUTE
MUTE Rast2
3.92
GAT/TMUTE DTMF SLPE
TMUTE DTMF
Rast3 Rbal1
Cgat
Rgat
Rslpe
Creg
Cbal
Rbal2
Fig. Basic application measurements
TEA1118/A versatile cordless transmission
Application Note
characteristics supply block
Without influence characteristics (except slight difference very line current), TEA1118/A used different supply configurations: they provide supply peripheral circuits like from TEA111x family line interfaces they externally supplied external power supply available.
3.1.1
characteristics
Principle operation 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 apparatus, TEA1118/A 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.
Rgasint from preamp Rexch Rline Iline
Vexch
Cvcc
Creg
Islpe
SLPE
Rslpe
Fig. characteristics configuration regulate line voltage between pins SLPE. voltage calculated Vref Rslpe Islpe Islpe Iline Iline line current current consumption supply current peripherals Current consumption between
TEA1118/A versatile cordless transmission
Application Note
line current Iline flowing into apparatus determined exchange supply voltage Vexch, feeding bridge resistance Rexch, resistance telephone line Rline voltage across apparatus including diode bridge. Below threshold line current (typically equal internal reference voltage (generating Vref) automatically adjusted lower value (down absolute minimum voltage this range, shape curve giving Vref versus line current slightly different used supply peripheral circuits TEA1118/A supplied from external supply. This means that more sets operate parallel that very voltage feeding bridge line current higher value. line currents below this threshold current, TEA1118/A reduced sending receiving performances. This called voltage area. internal circuitry TEA1118/A 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
TEA1118/A versatile cordless transmission
Application Note
Fig. shows behavior voltage area line powered condition while fig. shows this behavior when externally powered.
Fig. voltage behavior line powered conditions
Fig. voltage behavior with external power supply Adjustments performances reference voltage, Vref, adjusted means external resistor Rva. increased connecting resistor between pins SLPE (see fig; 11), decreased connecting resistor between pins case 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). 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").
TEA1118/A versatile cordless transmission
Application Note
Fig. Influence resistor between SLPE 15mA slope voltage influenced Rslpe resistor shown fig. preferred value Rslpe changing this value will affect more than characteristics, also influences gains, characteristics, maximum output swing line voltage threshold Ith.
Fig. Influence Rslpe characteristics
3.1.2
Supply peripherals
This sub-chapter concerns line powered applications which usual these ICs. Principle operation supply voltage normally used supply internal circuitry TEA1118/A. However, small current drawn supply peripheral circuits having ground reference. supply voltage depends current consumed peripheral circuits shown following formula: VCC0 Rccint (Iqr VCC0 internal current necessary supply receive output amplifier when there signal Rccint internal equivalent impedance between
TEA1118/A versatile cordless transmission
Application Note
Rccint output impedance voltage supply point. seen from fig. 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 Rccint which include parallel impedance internal circuitry connected between VEE. line current equal equal this Rccint impedance limited minimum value ensure correct operation, will limited maximum value. 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 behave 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 (called impedance) mainly determined resistor. Fig. shows equivalent schematic impedance.
Vref
Creg Rslpe internal resistor
SLPE
Rslpe
Creg
Cvcc
Fig. Equivalent impedance
Adjustments performances When decreasing reference voltage Vref, resistor connected between parallel (see fig. slightly modifying impedance. complex impedance required, resistor resistor replaced complex network (see fig. :Rcc Cz). resistance which influences value becomes
TEA1118/A versatile cordless transmission
Application Note
Transmit amplifier
Principle operation fig. block diagram transmit amplifier TEA1118/A depicted.
from DTMF (TEA1118A only)
(TEA1118 only)
circuit
Rgasint
Rexch
Creg
SLPE
Rslpe
Cvcc
Cexch
Fig. Transmit channel transmit amplifier symmetrical high input impedances (typically times between pins with maximum tolerances 15%). input this transmit amplifier able handle signals mVrms with less than total harmonic distortion. seen from fig. transmit amplifier itself built parts: preamplifier which realizes voltage current conversion, end-amplifier which realizes current voltage conversion. overall gain (Gvtx) transmit amplifier from inputs TX+/TX- output given following equation: Gvtx Avtx Avtx 0.016 (Rgasint Rrefint) (Ri//Zline Rslpe) with: apparatus impedance, Rcc//Rp (typically 15.5 Rgasint internal resistor realizing current voltage conversion (typically 27.6 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) Using these typical values equation assuming Zline find gain equal
TEA1118/A versatile cordless transmission
Gvtx Avtx
Application Note
Iline
different gain controls (AGC; MUTE TMUTE TEA1118A only) transmit preamplifier stage, modifying transconductance. Adjustments performances TEA1118 only, transmit gain decreased connecting resistor Rgat between pins REG. adjusted from suit application specific requirements, however, this gain adjustment slightly increases gain spread affects temperature coefficient matching between internal external resistors. Fig. shows typicall curve transmit gain versus external resistor Rgat. gain dependancy this external Rgat resistor given following equation: Gvtx 0.016 (Rgasint//Rgat Rrefint) (Ri//Zline Rslpe)
Fig. Transmit gain versus Rgat connected between capacitor Cgat connected between pins TEA1118 provide first order lowpass filter which cut-off frequency determined product Cgat (Rgasint//Rgat). shows typical frequency response transmit amplifier (without filter) TEA1118/A.
Fig. Transmit gain versus frequency: influence temperature
TEA1118/A versatile cordless transmission
Application Note
shows distortion signal line function transmit signal nominal settings line current TEA1118/A, while fig. shows this distortion versus input transmit signal when transmit gain reduced TEA1118.
Fig. Distortion line versus transmit signal nominal gain TEA1118/A
Fig. Distortion line versus transmit signal gain TEA1118 Fig. shows distortion line signal versus input transmit signal line line current nominal gain when TEA1118/A powered from external power supply between VEE.
TEA1118/A versatile cordless transmission
Application Note
Fig. Distortion line signal Iline with external power supply Fig. shows transmit noise (psophometrically weighted: curve) versus line current nominal gain when resistor connected between inputs TX-.
Fig. Transmit noise versus line current Fig. shows common mode rejection ratio nominal transmit gain. curves present this fig. first spectrum signal when transmit signal applied TXwhile shorted VEE, second spectrum signal when transmit signal applied pins shorted together. Both signals kHz, difference between curves gives CMRR.
TEA1118/A versatile cordless transmission
Application Note
Fig. Common mode rejection ratio transmit
TMUTE function (TEA1118A only)
Principle operation transmit mute function realizes electronic switching between transmit amplifier sending DTMF amplifier. This function disables transmit channel provide kind privacy function same time enables DTMF channel needed some specific applications; this function effect receive channel. high level applied TMUTE input, transmit channel disabled while DTMF channel enabled, applying level leaving TMUTE open MUTE level low) transmit channel enabled. threshold voltage level 0.68 typically with temperature coefficient mV/°C. Fig. shows transmit gain reduction TMUTE input current versus TMUTE input voltage.
Fig. Transmit gain TMUTE input current versus TMUTE input voltage Adjustment performances Fig. shows transmit amplifier gain reduction Iline input signal kHz. curves present this fig. first shows spectrum signal line when signal applied transmit inputs when TMUTE level, second shows same signal when TMUTE high level. difference between curves this frequency gives gain reduction.
TEA1118/A versatile cordless transmission
Application Note
Fig. Transmit gain reduction TMUTE condition TMUTE function works down voltage equal below this threshold, transmit amplifier stays always enabled independently TMUTE input level. maximum voltage allowed TMUTE +0.4
Receive amplifier
Principle operation fig. block diagram receive amplifier depicted.
MUTE (TEA1118A only)
Rgarint
Vcc/2
DTMF (TEA1118A only)
Att.
Fig. Receive channel
TEA1118/A versatile cordless transmission
Application Note
receive amplifier a-symmetrical high input impedance between pins VEE. equal with maximum tolerance +/-15%. able drive loads down impedance seen from fig. receive amplifier itself built parts: preamplifier which realizes voltage current conversion end-amplifier which realizes current voltage conversion. overall gain Gvrx receive amplifier from input output given equation: Gvrx Avrx Avrx 1.21 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 Rgasint) 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 TEA1118A only) receive preamplifier stage, modifying transconductance. Adjustments performances receive gain decreased TEA1118/A 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 almost typically attenuation provided antisidetone network. Fig. shows typicall curve receive gain versus external resistor Rgar. gain dependancy this external Rgar resistor given following equation: Gvrx 1.21 (Rgarint//Rgar Rrefint)
Fig. Receive gain versus Rgar connected between
TEA1118/A versatile cordless transmission
Application Note
external capacitors Cgar (connected between Cgars (connected between VEE) ensure stability when relationship Cgars Cgar fulfilled. Cgar capacitor provides first order pass filter, which cut-off frequency determined with Rgarint//Rgar. Fig. shows frequency response receive amplifier different temperatures (Cgar Cgars nF).
Fig. Receive gain versus frequency 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 load line current
Fig. Distortion versus input signal
TEA1118/A versatile cordless transmission
Application Note
Fig. Distortion versus level with load Fig. shows noise loaded with (psophometrically weighted: curve) function line current. This curve been done with open input With antisidetone network connected input part transmit noise generated line will added but, thanks transmit noise value, effect negligible.
Fig. Noise
Automatic gain control
Principle operation TEA1118/A perform automatic line loss compensation. automatic gain control varies gain transmit receive amplifiers accordance with line current. enable this function, must connected VEE. line currents below current threshold, Istart (typically mA), gain control factor equal giving maximum value gains Gvtx Gvrx. this threshold
TEA1118/A versatile cordless transmission
Application Note
current exceeded, gain control factor reduced then gains controlled transmit 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 transmit receive controlled gains. gain control range both amplifiers typically which corresponds 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 optimized with exchange supply voltage feeding bridge line previously described. order with other configurations, resistor Ragc, inserted between pins VEE. This Ragc resistor increases threshold currents Istart Istop. Fig. shows control transmit gain versus line current different values Ragc. When function required, must left open, then control factor equals both controlled gains their maximum values.
Fig. transmit gain versus line current Ragc
DTMF amplifier (TEA1118A only)
principle operation fig. block diagram DTMF channel TEA1118A depicted.
TEA1118/A versatile cordless transmission
Application Note
MUTE
from transmit preamp
Rgarint
Att.
VCC/2
DTMF
Att.
TMUTE
from receive preamp
Rgasint
Transmit mute
Rexch
SLPE
Cvcc Rslpe
Cexch
Fig. DTMF channel TEA1118A DTMF amplifier a-symmetrical high input impedance between pins DTMF with maximum spread +/-15%. DTMF amplifier built three parts: attenuator factor preamplifier which realizes voltage current conversion same end-amplifier transmit amplifier. applied DTMF channel. overall gain (Gvmf) DTMF amplifier from input DTMF output given following equation: Gvmf Avmf Avmf 0.032 (Rgasint Rrefint) (Ri//Zline Rslpe) with: apparatus impedance, Rcc//Rp (typically 15.5 Rgasint internal resistor realizing current voltage conversion (typically 27.6 with spread +/-15%) Rrefint internal resistor determining current internal current stabilizer (typically with spread correlated spread Rgasint) Zline load impedance line during measurement Using these typical values equation assuming Zline find gain equal Gvmf Avmf 17.4
TEA1118/A versatile cordless transmission
Application Note
Fig. shows frequency response DTMF amplifier different temperatures.
Fig. DTMF gain versus frequency different temperatures 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
MUTE function (TEA1118A only)
Principle operation mute realizes electronic switching between speech mode dialling mode. high level applied MUTE input, both transmit receive channels disabled while DTMF channel enabled. applying level leaving MUTE open receive channel enabled moreover, TMUTE level low, transmit channel also enabled. threshold voltage level 0.68 typically with
TEA1118/A versatile cordless transmission
Application Note
temperature coefficient mV/°C. Fig. shows transmit gain reduction MUTE input current versus MUTE input voltage.
Fig. Transmit gain MUTE input current versus MUTE input voltage Adjustments performances Fig. shows transmit receive amplifier gain reduction Iline input signal kHz. curves present these graphics, first shows spectrum signal line when signal applied transmit inputs respectively when MUTE level, second shows same signal when MUTE high level. difference between curves this frequency gives gain reduction.
Fig. Transmit receive gain reduction MUTE condition TEA1118A MUTE function works down voltage equal below this threshold, transmit receive amplifiers stays always enabled independently MUTE input level. maximum voltage allowed MUTE input
TEA1118/A versatile cordless transmission
Application Note
Anti-sidetone network
Principle operation avoid transmit signal come back with high level receive channel, anti-sidetone circuit uses transmit signal from SLPE (which opposite phase) cancel transmit signal input receive amplifier. anti-sidetone bridge already used TEA106x TEA111x families conventional Wheatstone bridge shown fig. used design anti-sidetone network.
Rast1
Zline
Zbal
Zline
Rast2
Rslpe SLPE
Rast1
Rslpe Rast3 SLPE Zbal
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 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.
3.9.1
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. 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.
TEA1118/A versatile cordless transmission
1265
Application Note
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 derivated from following equation: Rast2 Rast1 Rast2 Rast2 Rast3 Zbal With values used this example, gives kHz. receive amplifier input impedance, typically
3.9.2
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.
TEA1118/A versatile cordless transmission
Application Note
APPLICATION COOKBOOK
this chapter, procedure making basic application given. Reffering fig. design flow given number steps which should made. possible every step, components involved their influence every step given.
Step
setting
Adjustment
Adjust setting TEA1118/A local requirements. Voltage LN-VEE This voltage adjusted changing Vref: increased with resistor between pins SLPE decreased down with resistor between slope might modified changing value Rslpe (this advised: gains modified, characteristic modified). line powered applications, depends values Vref resistive part impedance network (Rcc Rz). External power supply applied. value adjusted changing value Creg: smaller value speeds-up current shape during transients decreases value inductance then affects BRL.
slope
Supply point
Artificial inductor
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). Adjust Zbal (Rbal1, Rbal2, Cbal) according line characteristics. Internally defined, characteristics (Istart Istop) shiftted higher line currents with external Ragc resistor connected between VEE.
Sidetone
TEA1118/A versatile cordless transmission
Application Note
Step
Adjustment
TEA1118/A transmit receive gains Transmit gain transmit gain application adjusted preferably before entering pins TX+/TX- TEA1118/A. TEA1118 only, also possible reduce transmit gain with resistor Rgat. Ctx1, Ctx2 TX+/TX- input impedance form high-pass filter. capacitor Cgat parallel with transmit gain resistor (between TEA1118 pins GAT) form low-pass filter. receive gain application adjusted preferably after output nevertheless, possible reduce receive gain with resistor Rgar. capacitor parallel with receive gain resistor (between TEA1118/A pins GAR) form low-pass filter, stability ensured with capacitor Cgars (>10 Cgar) between pins VEE.
Receive gain
TEA1118A only DTMF gain DTMF DTMF level line must adjusted before entering DTMF. selected with high level either TMUTE MUTE.
TEA1118/A versatile cordless transmission
Application Note
EXAMPLE APPLICATION
demo board (OM4789) available, TEA1118/A used various applications, this demo board includes only TEA1118A with basic environment. Replacing TEA1118A TEA1118 make usable also evaluation TEA1118 which offers possibility reduce transmit gain. Fig. gives basic application TEA1118/A. this schematic, capacitors connected with doted lines resistors drawn with dotted lines indicated immunity purpose.
TEA1118/A versatile cordless transmission
Application Note
+VCC
Rprot
Cvcc
Rast1
Rtx3
Rtx2
Ctx2
1N4004
Rtx1
Ctx1
TEA1118AT
(TEA1118T)
Cgars
Cgar
Rgar Cear
Ragc
MUTE Rast2
3.92
STR1 STR2
MUTE TMUTE
TMUTE
(GAT)
DTMF SLPE Rast3 Rbal1
Cgat
Rgat
Rslpe
Creg
Cbal
Rbal2
Fig. Basic application TEA1118A
TEA1118/A versatile cordless 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. TX+/TX- inputs also sensitive signals entering these pins would amplified). Care taken with lay-out transmit amplifier, which also helpfull noise, providing good decoupling GND. low-pass filter 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. TXP, TXM, demoboard), better filter signal before influences close environment TEA1118/A (e.g. action C1,C2,C11 demoboard).
TEA1118/A versatile cordless transmission
Application Note
REFERENCES
TEA1118/A Versatile cordless transmission circuit Device specification TEA1118/A Line Interface Demonstration Board USER MANUAL OM4789 (report CTT96001) Philips Semiconductors SEMICONDUCTORS TELECOM SYSTEMS -IC03-
TEA1118/A versatile cordless transmission
Application Note
APPENDIX LIST ABBREVIATIONS DEFINITIONS
DTMF Gvmf Gvrx Gvtx Iline Islpe Istart Istop MUTE TMUTE OM4789 Rast Rexch 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 TEA1118/A Transmit gain adjustment TEA1118 Ground DTMF amplifier gain Receive gain Transmit gain Integrated circuit Current consumption TEA1118/A Line current Current consumption peripherals Internal current consumption (fromVCC) receive amplifier Receive amplifier input TEA1118/A 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 TEA1118A TMUTE input TEA1118A (transmit channel) Demoboard TEA1118A Receive amplifier output TEA1118/A Resistor adjust sidetone bridge attenuation Antisidetone resistor Filter capacitor equivalent inductor connection TEA1118/A Bridge resistance exchange Radio Frequency Interference
TEA1118/A versatile cordless transmission
Application Note
Rgar Rgarint Rgasint Rgat SLPE TX+/TXVCC Vref Vslpe Zbal
External resistance reduce receive gain TEA1118/A Internal resistance (100 which sets receive gain Internal resistance which sets transmit gain External resistance reduce transmit gain TEA1118 Internal resistance between Slope input TEA1118/A Total Harmonic Distortion Transmit amplifier input pins TEA1118/A Positive supply TEA1118/A Ground reference TEA1118/A voltage between Stabilized reference voltage between SLPE voltage level between SLPE Input impedance receive amplifier TEA1118/A Anti-sidetone network Gain control factor

AN96071 TEA1118/A versatile cordless transmission Applicatio

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