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unisonic technologies co., ltd mc34118 linear integrated circuit www.unisonic.com.tw 1 of 12 copyright ? 2009 unisonic technologies co., ltd qw-r108-007,d voice switched speaker-phone circuit ? description as a voice switched speaker-phone integrated circuit, the utc mc34118 includes the necessary amplifiers, attenuators, level detectors and control algorithm. to form the utc mc34118 ?s internal circuit, there is an internal microphone amplifier with adjustable gain and mute control, internal transmit and receive attenuators (operate in a complementary manner), level detectors at both in put and output of both attenuators, and background noise monitors for both the transmit and receive channels. the dial tone can be pretended fr om being attenuated by the receive background noise monitor circuit by a dial tone detector. there are also two line driver amplifiers which can be used to form a hybrid network in conjunction with an external coupling transformer. a high-pass filter can be used for other filtering functions, and especially to filter out 60hz noise in the receive channel. the utc mc34118 which requiring typically 5ma may be operated from a power supply, or it can be powered from the telephone line. ? features * attenuator gain range: 52db (between transmit and receive) * for line-powered applications : 3~6.5v low voltage operation * for improved sensitivity :4-point signal sensing * for transmit and receive paths: background noise monitors * external resistors set microphone amplifier gain * mute function included * chip disable: active or standby operation * during dial tone presence: dial tone detector to inhibit receive idle mode dip-28 sop-28 sdip-28 lead-free: mc34118l halogen-free: mc34118g ? ordering information ordering number normal lead free plating halogen free package packing MC34118-D28-T mc34118l-d28-t mc34118g-d28-t dip-28 tube mc34118-e28-t mc34118l-e28-t mc34118g-e28-t sdip-28 tube mc34118-s28-t mc34118l-s28-t mc34118g-s28-t sop-28 tube mc34118-s28-r mc34118l-s28-r mc34118g-s28-r sop-28 tape reel
mc34118 linear integrated circuit unisonic technologies co., ltd 2 of 12 www.unisonic.com.tw qw-r108-007,d ? pin description pin no pin name description 1 fo output of filter. the output impedance is less than 50 ? . 2 fi input of filter. the in put impedance is less than 1m ? . 3 cd chip disable input .a logic low (voltage lo wer than 0.8v) sets normal operation. a logic high (voltage higher than 2v) disable the ic. this pin?s input impedance is 90 k ? nominally. 4 v cc this pin requires a supply voltage of +2.8v ~ +6.5v at 5ma. after v cc falls from 3.5v ~ 2.8v, when in the receive mode, an agc circuit reduces the receive attenuator gain by 25db. 5 hto+ the output of the second hy brid amplifier. this amplifier?s gain is internally set at -1. 6 hto- output of the first hybrid amplifier. this amplifier?s gain of the amplifier is set by external resistors. 7 hti the first hybrid amplifier?s input and summing node. dc level is about equal to vb. 8 txo the transmit attenuator?s output. dc level is about vb. 9 txi the transmit attenuator?s input. it?s maximum signal level is 350 mvrms. the input impedance is 10k ? . 10 mco the microphone amplifier?s output. this amplifier?s gain is set by external resistors. 11 mci the summing node of the microphone?s input. dc lever is vb. 12 mut input of mute. a logic low (voltage lower than 0.8v) sets the circuit normal operation. a logic high (voltage higher than 2v) mutes t he microphone amplifier, but it doesn?t affect the rest of the circuit. the input impedance is 90 k ohms. 13 vlc the input of volume control. in the receive mode, when vlc=vb, the receive attenuator is at maximum gain. the receiv e gain is down 35db when vlc=0.3db, and it does not effect the transmit modes. 14 ct at this pin, to switch modes, t he rc sets the response time for the circuit. 15 vb in this pin, there?s an output voltage=v cc/2 which is a system ac ground and biases the volume control. what r equired is a filter capacitor. 16 cpt the time constant for the transmit backg round side can be set by the rc at this pin . 17 tli2 the input to the transmit level detecto r which is on the microphone/ speaker side. 18 tlo2 the output to the transmit level detector which is on the microphone/ speaker side. also the input to the transmit background monitor. 19 rlo2 the output of the receive level det ector which is on the microphone/ speaker side 20 rli2 the input to the receive level detec tor which is on the microphone/ speaker side 21 rxi the input to the receive attenuator and dial tone detector. in this pin, the maximum input level is 350mvrms,and the input impedance is 10k ? . 22 rxo the output of the receive atte nuator. this pin?s dc level is vb. 23 tli1 the input to the transmit leve l detector which is on the line side. 24 tlo1 the output to the transmit level detector which is on the line side, and also the input to the transmit background monitor. 25 rlo1 the output of the receive leve l detector which is on the line side. 26 rli1 the input to the receive leve l detector which is on the line side. 27 cpr the time constant for the receive backgroun d monitor can be set by the rc at this pin. 28 gnd ground.
mc34118 linear integrated circuit unisonic technologies co., ltd 3 of 12 www.unisonic.com.tw qw-r108-007,d ? block diagram background noise monitor level delector altenuator conrol agc lever detector r x attenuator background noise monitor t x attenuator v cc cd gnd vb rlo2 tlo2 cpt mut mci mco tli2 ct txi txo tli1 hti hto- vb vb hto+ cpr fo tol1 rlo1 fi rli1 rxi vb rxo vlc rli2 12 10 17 14 9 8 23 7 6 5 27 25 24 4 28 15 26 21 22 13 20 1 2 3 19 18 16 11
mc34118 linear integrated circuit unisonic technologies co., ltd 4 of 12 www.unisonic.com.tw qw-r108-007,d ? absolute maximum rating ( ta=25 ,voltages referred to pin 22) parameter symbol ratings unit supply voltage v cc -1~7 v voltage at pin 3 v3 -1~v cc +1 v voltage at pin 12 ( mute) v12 -1~v cc +1 v voltage at pin 13 ( vlc) v13 -1~v cc +0.5 v voltage at pin 9, pin 21, and pin 2 v9, 21, 2 -0.5~ v cc +0.5 v storage temperature t str -65~+150 note: absolute maximum ratings are those values beyond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. ? recommended operation conditions parameter symbol ratings unit supply voltage v4 3.5~6.5 v voltage at pin 3 v3 0~ v cc v voltage at pin 12 ( mute) v12 0~ v cc v voltage at pin 13 ( vlc) v13 0. 3 vb~vb v ivb current ( pin 15) i vb 500 a attenuator input signal voltage at pin 9, pin 21 v9, v21 350 mvrms rxo, txo(pin8, pin 22) 0~+-2 ma mco(pin 10) 0~+-1 ma load current hto-, hto+(pin 6, pin5) 0~+-0.5 ma ambient operating temperature t opr -20~+60 ? electrical characteristics (ta=25c) parameter symbol test conditions min typ max unit supply voltages v cc =6.5v, cd=0.8v 5.5 8 ma v+ supply current i cc v cc =6.5v, cd=2v 600 800 a cd input resistance r cd v cc =v cd =6.5v 50 90 k ? high v cdh 2 v cc v cd input voltage low v cdl 0.8 v v cc =3.5v 1.3 v v b output voltage v b v cc =5v 1.8 2.1 2.4 v b output resistance r ovb i vb =1ma 400 ? v b power supply rejection ratio psrr c vb =220f, f=1khz 54 db attenuators r x mode, r xi =150mvrms g rx v cc =5v 4 6 8 db r x mode, r xi =150mvrms g rx v cc =3.5v 4 6 8 db gain change g rx1 v cc =3.5v vs. v cc =5v -0.5 0 +0.5 db agc gain change g rx2 v cc =3.5v vs. v cc =5v -25 -15 db idle mode, r xi =150mvrms g rxi -22 -20 -17 db receive attenuator gain (f=1khz, v lc =v b ) r x to t x mode range g rx3 49 52 54 db volume control range v cr 27 35 db r xo dc voltage v rxo r x mode v b v r xo dc voltage v rxo r x to t x mode +-10 +-150 mv r xo high voltage v rxoh i out =-1ma, r xi =v b +1.5v 3.7 v r xo low voltage v rxol i out =+1ma, r xi =v b -1v, output measured with respect to v b -1.5 -1 v r xi input resistance r rxi r xi < 350mvrs 7 10 14 k ?
mc34118 linear integrated circuit unisonic technologies co., ltd 5 of 12 www.unisonic.com.tw qw-r108-007,d ? electrical characteristics(cont.) parameter symbol test conditions min typ max unit transmit attenuator gain (f=1khz) t x mode, t xi =150mvrms g tx 4 6 8 db idle mode, t xi =150mvrms g txi -22 -20 -17 db t x to rx mode range g txi 49 52 54 db t x o dc voltage v txo t x vb v t xo dc voltage v txo t x to r x mode +-30 +-150 mv t xo high voltage v txoh i out =-1ma, t xi =v b +1.5v 3.7 v t xo low voltage v txol i out =+1ma, t xi =v b -1v, output measured with respect to v b -1.5 -1 v t xi input resistance r txi t xi < 350mvrs 7 10 14 k ? gain tracking g tr g rx +g tx , @t x , i die , r x +-0.1 db attenuator control r x mode v lc =v b 240 mv idle mode 0 mv ct voltage ( ct-v b ) t x mode -240 mv ct source current i ctr (switching to r x mode) -85 -60 -40 a ct sink current i ctt (switching to t x mode) +40 +60 +85 a ct slow idle current i cts 0 a ct fast idle inte rnal resistance r fi 1.5 2 3.6 k ? vlc input current i vlc -60 na dial tone detector threshold v dt 10 15 20 mv microphone amplifier ( v mut < 0.8v, a vcl =31db, unless otherwise specified) output offset m covos v mco -v b , r f =180 k ? -50 0 50 mv open loop gain a volm f < 100hz 70 80 db gain bandwidth g bwm 1 mhz output high voltage v mcoh i out =1ma, v cc =5v 3.7 v output low voltage v mcol i out =1ma 200 mv input bias current i bm @mci -40 na muting( gain) g mt f=1khz, v mut =2v 300hz < f < 10khz -55 -68 db mut input resistance r mut v cc =v mut =6.5v 50 90 k ? mut high input voltage v muth 2 vcc v mut low input voltage v mutl 0 0.8 v distortion thd m 300hz < f < 10khz 0.15 % hybid amplifier hto-offset h vos v hto -~v b , r f =51k ? -20 0 20 mv hto- to hto+ offset h bvos r f =51k ? -30 0 30 mv open loop gain a volh h ti to h to- , f<100hz 60 80 db gain bandwidth g bwh 1 mhz closed loop gain a vclh h to- to h to+ -0.35 0 0.35 db input bias current(@hti) i bh -30 na hto- high voltage v ht-h i out =-5ma 3.7 v hto- low voltage v ht-l i out =+5ma 250 mv hto+ high voltage v ht+h i out =-5ma 3.7 v hto+ low voltage v ht+l i out =+5ma 450 mv distortion thd m 300hz < f < 10khz 0.3 %
mc34118 linear integrated circuit unisonic technologies co., ltd 6 of 12 www.unisonic.com.tw qw-r108-007,d ? electrical characteristics(cont.) parameter symbol test conditions min typ max unit level detectors and background noise monitors transmit-receive switching threshold( ratio of current at rli1+rli2 to 20 a at tli1+tli2 to switch from tx to rx) i th 0.8 1 1.2 source current at rlo1, rlo2, tlo1, tlo2 i lso -2 ma sink current at rlo1 , rlo2, tlo1, tlo2 i lsk 4 a cpr, cpt output resistance r cp i out =1.5ma 35 ? cpr, cpt leakage current i cplk -0.2 a filter voltage offset at fo f ovos v fo -v b , 220k ? from v b to fi -200 -90 0 mv fo sink current i fo 150 260 400 a fi bias current i fi -50 na system distortion (f=1khz) r x mode thd r from f i to r xo , f o connected to r xi 0.5 3 % t x mode thd from mci to h to- /h to+ , includes t x attenuator 0.8 3 % ? temperature parameters parameter typ ratings (ta=25 ) typ change unit v cc supply current(cd=0.8v) 5ma -0.3 %/ v cc supply current(cd=2v) 400a -0.4 %/ v b output voltage (v cc =5v) 2.1v +0.8 %/ attenuator gain (max gain) 6 0.0008 db/ attenuator gain (max attenuation) -46db 0.004 db/ attenuator input resistance 10k ? 0.6 %/ dial tone detector threshold 15mv 20 v/ ct source, sink current 60a -0.15 %/ microphone, hybrid ampl ifier offset 0mv 4 v/ transmit-receive switching threshold 1 0.02 %/ sink current at rlo1, rlo2, tlo1, tlo2 4a -10 na/ closed loop gain( hto- to hto+) 0db 0.001 %/
mc34118 linear integrated circuit unisonic technologies co., ltd 7 of 12 www.unisonic.com.tw qw-r108-007,d ? functional description introduction between operation of a speakerphone and a handset, the f undamental difference is that of half-duplex versus full-duplex. the utc mc34118 includes the necessary level detectors, attenuators, and switching control for a properly operating speakerphone. the detection sensitiv ity and timing can be externally controlled. the utc mc34118 also provides background noise monitors to make t he circuit insensitive to room and line noise, hybrid amplifier to interface to tip and ring, the micr ophone amplifier, and other associated functions. attenuators the transmit and receive attenuators are complementary in function, and they are never both fully on or both fully off. for example, when one is at maximum gain: +6db , the other is at maximum attenuation: - 46db, and vice versa. but sum of their gains remains constant at -40d b typically. to control the transmit and receive paths to provide the half-duplex operation re quired in speakerphone is the attenu ators? purpose. the attenuators are non-inverting, have a -3db (from max gain) frequency of ~ 100khz, their input impedance of each one is nominally 10k ? , and to prevent distortion, their input signal should be limited to 350 mvrms(same as 990mvp-p). after the output current limit (typically 2.5ma) is reached, the output impedance is < 10 ? . 96k ? 4.0k ? 10k ? to attenuator input vb txi/rxi these attenuators can be controlled by the control blo ck?s output signal. when the ct pin which measures the signal is at +240mv with respect to vb, the circuit is in the receive mode and so receive attenuator is at +6db. when the ct voltage is equal to vb, the circuit is in an idle mo de, and it also causing the attenuators? gains to be halfway between their fully on and fully off positions (typical -20 db each). the most direct method to monitor the circuit?s mode is monitoring the ct voltage (with respect to vb). level detectors there are two level detectors on the receive side and tw o level detectors on the transmit side. the terms in parentheses form one system, and the other terms form the se cond system. all the four level detectors are high amplifiers which have back-to-back diod es in the feedback path, and then it is resulting in non-linear gain, which permits operation over a wide dynamic range of speech leve ls. tli1, tli2, rli1, and rli2, the external resistor and capacitor determine the sensitiv ity of each level detector. through a diod e each output charges an external capacitor and limiting resistor, thus providing a dc representation of the input ac signal level. the capacitor and an internal 350 ? resistor provide the outputs? quick rise time. and an in ternal current source and the capacitor set a slow decay time. on the receive side, rli1 is at the receive input re ceiving the same signal as at tip and ring, and rli2 is at the output of the speaker amplif ier. on the transmit side, tli2 is at the microphone amplifier, while tli1 is at the hybrid output.
mc34118 linear integrated circuit unisonic technologies co., ltd 8 of 12 www.unisonic.com.tw qw-r108-007,d ? functional description(cont.) background noise monitors to distinguish speech (consists of burst s) from background noise (a relatively constant signal level) is the main purpose of the background noise monitors. there is one background noise monitor for the receive path and another one for the transmit path. the receive background noise monitor is operated on by the rli1-rlo1 level detector, as same as the transmit background noise monitor is operated on by the tli2-tlo2 level detector. by storing a dc voltage representative of the respective noise levels in capacitors at cpr and cpt, the background noise can be monitored. at these pins, the voltages have slow rise times which determined by the external rc, but fast decay times. the voltage at the non-inverti ng input of the monitor?s output compar ator won?t be more positive than the voltage at cpr/cpt when the signal at rli1/tli2 changes slowly. but while speech is present, it will rise quicker than the voltage at the invert ing input, causing its output to change. t he term?s output is sensed by the attenuator control block. volume control at vlc (pin 13) is the volume control input which is sensed as a voltage with respect to vb. only in the receive mode the volume control affects the att enuators. in the receive mode, the receive attenuator?s gain will be +6db, and the transmit attenuator?s gain will be -46db when vlc is equal to vb. when vlc is reduced below vb, the receive attenuator?s gain is reduced, and the transmit attenuator?s gain is increased, but the sum of them tow remains constant. out of the pin vlc, the bias current is typically 60na. dial tone detector this detector is a comparator with one side connected to rxi and one side input connected to vb with a 15mv offset. under this situation: the circuit is in the rece ive mode, and the incoming sign al is greater than 15mv, the comparator?s output will change, dis abling the receive idle mode. then receive attenuator will be at a setting only determined by the volume control.
mc34118 linear integrated circuit unisonic technologies co., ltd 9 of 12 www.unisonic.com.tw qw-r108-007,d ? functional description(cont.) agc the agc circuit only affects the circuit under such situati on: when the circuit is in the receive mode, and when v cc is less than 3.5v. as while as v cc falls below 3.5 volts, the transmit path attenuation changes so that the sum of the transmit and receive gains remains constant. attenuator control block this block has the seven: * c1: the output of the comparator operated by rlo2 and tlo2 (here means in microphone/ speaker side). * c2: the output of the comparat or operated by rlo1 and tlo1 (here means tip/ ring side). * c3: the output of the transmit background noise monitor. * c4: the output of the receive background noise monitor. * volume control * dial tone detector * agc circuit the c1~c4 effect is as follows: inputs c1 c2 c3 c4 output t x t x 1 x transmit mode t x r x y y fast idle mode r x t x y y fast idle mode r x r x x 1 receive mode t x t x 0 x slow idle mode t x r x 0 0 slow idle mode r x t x 0 0 slow idle mode r x r x x 0 slow idle mode switching to the full transmit or receive from an y other mode is at the fast rate (~30 ms). x :don?t care y :c3,c4 are not both 0
mc34118 linear integrated circuit unisonic technologies co., ltd 10 of 12 www.unisonic.com.tw qw-r108-007,d ? functional description(cont.) definition of the above is as follows: trems definition transmit the transmit attenuator is fully on: +6db. and the re ceive attenuator is at max. attenuation :-46db receive both attenuators are controlled by t he volume control. at max. volume the receive attenuator is fully on: +6db, and the transmit attenuat or is at max.attenuation:-46db. fast idle both transmit and receive speech are present in approximately equal levels. the attenuators are quickly switched to idle until one speech level dominates the other. slow idle speech has ceased in both transmit and receive path s. the attenuators are then slowly switched to the idle mode. a summary of the truth table is: 1. under all the below situations the circuit will switch to transmit : (1) both transmit level detectors sense signals rela tive to the respective receive level detectors tli1 versus rli1, tli2 versus rli2 (2) the transmit background noise monitor indicates the presence of speech. 2. under all the below situations the circuit will switch to receive (1) both receive level detectors sense higher signal leve ls relative to the respective transmit level detectors (2) the receive background noise monitor indicates the presence of speech. 3. under all the below situations the circ uit will switch to the fast idle mode: (1) if the level detectors disagree on the re lative strengths of the signal levels (2) at least one of the background noise monitor indicates speech. there are two conditions which can cause the fast idle mode to occur: (a) when both talkers are attempting to gain contro l of the system by talking at the same time (b) when one talker is in a very noisy environment, forcing the other to continually ove r-ride that noise level. in general, the fast idle mode will occur infrequently. 4. under any of the below si tuations the circuit will switch to the slow idle mode (1) both talkers are quiet( no speech present) (2) when one talker?s speech level is continuously ov er-ride by noise at the other speaker?s location. ct pin (pin14) determine the time required to switch the circuit between transmit, receive, fast idle, and slow idle. a schematic of the ct circuitry operates as follows: * rt =120k ? (typ.), and ct =5f (typ.). * switching to the receive mode i1 is turned on; i2 is off, charging the external capacitor to +240mv above vb an internal clamp prevents furt her charging of the capacitor). * switching to the transmit mode i2 is turned on; i1 is off, bringing down the voltage on the c apacitor to -240mv with respect vb.
mc34118 linear integrated circuit unisonic technologies co., ltd 11 of 12 www.unisonic.com.tw qw-r108-007,d ? functional description(cont.) * switch to id le quickly, the current sources are turned off, the internal 2k ? resistor is switched in discharging the capacitor to vb with a time = 2k ? x ct. * switching to idle slowly the current sources are turned off the switch at the 2k ? resistor is open discharging the capacitor to vb through the external resistor rt with a time=rt x ct. microphone amplifier while the inverting input and the output are pinned out, pins 10/11 ,the microphone amplifier, has the non-inverting input internally connected to vb. this ampl ifier?s open loop gain is typically 80db when f<100hz, and the gain bandwidth is typically 1mhz. its maximum output swin g (p-p) is typically 1 volt. mci?s input bias current is typically 40na out of the pin. hybrid amplifier at hto+, hto-, and hti, the two hybrid amplifiers provide the two-to-four wire converter for interfacing to the telephone line. the first amplifier?s gain is set by external resistor, and the first amplifier?s output drives the second amplifier (gain of -1). filter the external components determined t he operation of the filter circuit. power supply, vb, and chip disable for normal operation the power supply voltage is to be between 3.5v and 6.5v, but with reduced operation the v cc is possible 2.8 volts. vb?s output voltage is ~ (vcc-0.7)/2, and also provides the ac ground.
mc34118 linear integrated circuit unisonic technologies co., ltd 12 of 12 www.unisonic.com.tw qw-r108-007,d ? typical application circuit utc assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all utc products described or contained herein. utc products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.

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