unisonic technologies co., ltd mc34018 linear integrated circuit www.unisonic.com.tw 1 of 8 copyright ? 2005 unisonic technologies co., ltd qw-r108-006,c voice switched speaker-phone circuit ? description the utc mc34018 speaker-phone integrated circuit includes all the active circuitry and control functions to implement a high quality hands-free telephone sy stem. the circuit includes a microphone amplifier, a speaker amplifier, level detectors, a background sound level monitoring system in both the transmit and receive channels and an attenuation system which can control the transmit and receive levels as well as the background level. the applications include household and office speaker-phones, intercom systems, hand free kit for mobile phones, and others. ? features * chip select pin for power conservation (active/standby mode). * integrated all necessary active circuitry for a hand-free telephone into one single chip. * operating under wide dynamic range through signal compression technology. * build-in voltage regulators illuminate external regulators for lining operation. * monitoring system for background noise level. * background sound level compensation for transmit and receive levels as well as the background level. * power audio amplifier for typical 100mw output (into 25 ? ) with peak limiting for speaker to minimize distortion. * volume control function for exte rnal volume control circuit. *pb-free plating product number:mc34018l ? ordering information order number normal lead free plating package packing mc34018-d28-t mc34018l-d28-t dip-28 tube mc34018-e28-t mc34018l-e28-t sdip-28 tube MC34018-R28-R mc34018l-r28-r ssop-28 tape reel mc34018-r28-t mc34018l-r28-t ssop-28 tube mc34018-s28-r mc34018l-s28-r sop-28 tape reel mc34018-s28-t mc34018l-s28-t sop-28 tube mc34018l-d28-t (1)packing type (2)package type (3)lead plating (1) r: tape reel, t: tube (2) d28: dip-28, e28: sdip-28, s28: sop-28, r28: ssop-28 (3) l: lead free plating, blank: pb/sn
mc34018 linear integrated circuit unisonic technologies co., ltd 2 of 8 www.unisonic.com.tw qw-r108-006,c ? pin configuration 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 rr rtx txi txo tli tlo rli rlo mci mco cp1 cp2 xdi skg rrx rxi rxo acf v lc xdc gnd v b v cc ski cs agc v+ sko ? pin description pin no. pin name description 1 rr a resistor to ground provides a referenc e current for the transmit and receive attenuators 2 rtx a resistor to ground determines the nominal gain of the transmit attenuator, the transmit channel gain is inversely proportional to rtx resistance. 3 txi transmit attenuator input, input resistance is nominally 5.0k . 4 txo transmit attenuator output, the txo output si gnal drivers the input of transmit level detcetor, as well as the external ci rcuit which drivers the telephone line. 5 tli transmit level detector input. an external resi stor ac coupled to the tli pin sets the detection level. decreasing this resistor in creases the sensitivity to transmit channel signals. 6 tlo transmit level detector output. the external resistor and capacitor set the time the comparator will hold the system in the transmit mode after speech ceases. 7 rli receive level detector input. an external resi stor ac coupled to the rli pin sets the detection level. decreasing this resistor increa ses the sensitivity to receive channel signals. 8 rlo receive level detector output. the external resistor and capacitor set the time the comparator will hold the system in the receive mode after speech ceases. 9 mci microphone amplifier input. input impedance is nominally 10k and the dc bias voltage is approximately equal to v b 10 mco microphone amplifier output. the mic am p gain is internally set at 34db (50v/v). 11 cp1 a parallel resistor and capacitor connected between this pin and v cc holds a voltage corresponding to the background noise level. the transmit detector compares the cp1 voltage with the speech signal from cp2. 12 cp2 a capacitor at this pin peak detects the speec h signals for comparison with the background noise level held at cp1. 13 xdi input to the transmit detector system. the mi crophone amplifier output is ac coupled to the xdi pin through an external resistor. 14 skg high current ground pin for the speaker amplif ier output stage. the skg voltage should be within 10mv of the ground voltage at pin 22.
mc34018 linear integrated circuit unisonic technologies co., ltd 3 of 8 www.unisonic.com.tw qw-r108-006,c ? pin description(cont.) pin no. pin name description 15 sko speaker amplifier output. the sko pin will source and sink up to 100ma when ac coupled to the speaker. the speaker amplifier gain is internally set at 34db (50v/v). 16 v+ input dc supply voltage. v+ can be powere d from tip and ring if an ac decoupling inductor is used to prevent loading ac line si gnals. the required v+ voltage is 6.0v to 11v (7.5v nominal) at 7.0ma. 17 agc a capacitor from this pin to v b stabilizes the speaker ampl ifier gain control loop, and additionally controls the attack and decay time of this circuit. the gain control loop limits the speaker amplifier input to prevent clipping at sko. the internal resistance at agc pin is nominally 110k . 18 cs digital chip select input. when at a logic "0" (<0.7v) the v cc regulator is enabled. when at a logic "1" (>1.6v),the chip is in the stan dby mode drawing 0.5ma.an open cs pin is a logic "0".input impedance is nominally 140k ohms. the input voltage should not exceed 11v. 19 ski input to the speaker amplifier. input impedance is nominally 20k . 20 v cc a 5.4v regulated output which powers all circui ts except the speaker amplifier output stage. v cc can be used to power external circuitry such as a microprocessor(3.0ma max.) a filter capacitor is required. the utc mc34018 can be powered by a separate regulated supply by connecting v+ and v cc to a voltage between 4.5v and 6.5v while maintaining cs at a logic "1". 21 v b an output voltage equal to approximately v cc /2 which series as an analog ground for the speakerphone system. up to 1.5ma of external load current may be sourced from v b . output impedance is 250 ohms. a filter capacitor is required. 22 gnd ground pin for the ic(exc ept the speaker amplifier) 23 xdc transmit detector output. a resistor and capacitor at his pin hold the system in the transmit mode during pauses between words or phrases. when the xdc pin voltage decays to ground, the attenuators switch fr om the transmit mode to idle mode. the internal resistor at xdc is nominally 2.6k ohms(see fig.1). 24 v lc volume control input>connecting this pin to the s lider of a variable resistor provides receive mode volume control. the v lc pin voltage should be less than or equal to v b . 25 acf attenuator control filter. a capacitor connected to this pin reduces noise transient as the attenuator control switches level of attenuation. 26 rxo receive attenuator output. normally this pin is ac coupled to the input of the speaker amplifier. 27 rxi receive attenuator input. input impedance is nominally is 5.0k . 28 rrx a resistor to ground determines the nominal gain of the receive attenuator. the receive channel gain is directly proportional to the rrx resistance.
mc34018 linear integrated circuit unisonic technologies co., ltd 4 of 8 www.unisonic.com.tw qw-r108-006,c ? block diagram speaker
mc34018 linear integrated circuit unisonic technologies co., ltd 5 of 8 www.unisonic.com.tw qw-r108-006,c ? absolute maximum ratings (ta=25 , voltage referred to pin 22.) parameter symbol ratings unit v+ terminal voltage (pin 16) +12, -1.0 v cs (pin 18) +12, -1.0 v speaker amplifier ground(pin 14) +3.0, -1.0 v v lc (pin 24) +v cc , -1.0 v storage temperature t stg -65 ~ +150 c 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 v+ terminal voltage (pin 16) +6.0 ~ +11 v cs (pin 18) 0 ~ +11 v v lc (pin 24) 0.55v b ~ v b v receive signal(pin 27) 0 ~ 250 mvrms microphone signal(pin 9) 0 ~ 5.0 mvrms speaker amplifier ground (pin 14) -10 ~ +10 mvdc i cc (pin 20) 0 ~ 3.0 ma ambient temperature t a -20 ~ +60 c ? temperature characteristics (-20 ~+60 ) parameter pin typ change unit v+ supply current ( v+ 11v,pin 18 = 0.7v ) 16 -0.2 %/ c v+ supply current(v+ 11v,pin 18 = 1.6v ) 16 -0.4 %/ c v cc voltage( v+ = 7.5v ) 20 +0.1 %/ c attenuator gain ( max and min setting ) 0.003 db/ c delta rxo,txo voltage 4,26 0.24 %/ c speaker amp gain 15,19 0.001 db/ c microphone amp gain 9,10 0.4 db/ c microphone amp input resistance 9 +0.4 %/ c tx-rx switching threshold (20 a) 5,7 0.2 na/ c ? electrical characteristi cs (referred to fig.1) parameter symbol test conditions min typ max unit supply voltages v cc voltage v cc v+=7.5v 4.9 5.4 5.9 vdc line regulation v ccln 6.5v mc34018 linear integrated circuit unisonic technologies co., ltd 6 of 8 www.unisonic.com.tw qw-r108-006,c ? electrical characteristics (cont.) parameter symbol test conditions min typ max unit rxo voltage (rx mode) v rxo 1.8 2.3 3.2 mv delta rxo voltage (switch from rx to tx mode) v rxo 100 mv rxo sink current (rx mode) i rxol 75 a rxo source current (rx mode) i roxh 1.0 3.0 ma rxi input resistance r rxi 3.5 5.0 8.0 k volume control range v cr rx attenuator gain, rx mode, 0.6v b mc34018 linear integrated circuit unisonic technologies co., ltd 7 of 8 www.unisonic.com.tw qw-r108-006,c ? test circuit v b v b v b v b v b 19 26 28 27 4 1 2 3 25 21 8 7 6 5 9 10 13 12 11 23 18 16 20 22 17 15 14 24 vb regulator attenuator control receive/transmit comp transmit attenuator receive attenuator speaker amp peak limiter vcc regulator transmit detector comp vth (36mv) receive amp transmit log amp mic amp vcc vcc rlo vb vlc acf txi rr txo rrx rxi rtx rxo ski skg sko agc gnd vcc 5.4v v+ cs xdc cp1 cp2 xdi mco mci tli tlo rti 25 4.3k 18k 30k 91k 47 f 0.05 f 0.01 f 0.1 f 0.1 f 4.7 f 47 f 1.0 f vcc 24k 20k 2.2m vb 0.068 f 4.7k 1.0 f 2.2m 0.068 f 3.3k 2k 0.1 f 0.05 f 0.068 f 4.7k 4.7 f47 f 100k 47 f 200k 1000 f 47 f 1.0 f vcc 10k 12k 59k 33k 56k 500 500 dc line input receive input mic transmit output 2.6k v b fig 1 test circuit ? basic line powered speakerphone 0.01 f 0.05 f 1.0 f 1.0 f 0.05 f 0.068 f 0.068 mf 1.0 f 4.7 f 0.068 f 0.1 f 22k 470k 470k 15k 1000 f 47k 8.2k 0.068 f 0.01 f 2.2k 10 f 33k 47k 8.2k 8.2k 0.01 f 0.01 f fig 2
mc34018 linear integrated circuit unisonic technologies co., ltd 8 of 8 www.unisonic.com.tw qw-r108-006,c 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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