UTC1062 LINEAR INTEGRATED CIRCUIT LOW VOLTAGE TELEPHONE TRANSMISSION CIRCUIT WITH DIALLER INTERFACE DESCRIPTION The UTC1062 is a bipolar integrated circuit performing all speech and line interface function required DIP-16 in the fully electronic telephone sets. It performs electronic switching between dialing speech. The circuit is able to operate down to d.c. line voltage of 1.6v (with reduced performance) to facilitate the use of more telephone sets in parallel. FEATURES * Low d.c. line voltage; operates down to 1.6V (excluding polarity guard) * Voltage regulator with adjustment static resistance * Provides supply with limited current for external circuitry * Symmetrical high-impedance inputs (64kΩ ) for dynamic, magnetic or piezoelectric microphones * Asymmetrical high-impedance inputs (32kΩ)for electric microphones * DTMF signal input with confidence tone * Mute input for pulse or DTMF dialing SOP-16 * Receiving amplifier for several types of earphones * Large amplification setting range on microphone and ear piece amplifiers * Line loss compensation facility , line current dependent (microphone and ear piece amplifiers) * Gain control adaptable to exchange supply * Possibility to adjust the d.c. line voltage QUICK REFERENCE DATA Line voltage at Iline=15mA Line current operating range[pin1] normal operation with reduced performance Internal supply current Supply current for peripherals at Iline=15 mA mute input HIGH Vcc>2.2V Vcc>2.8V Voltage amplification range microphone amplifier receiving amplifier Line loss compensation Amplification control range Exchange supply voltage range Exchange feeding bridge resistance range Operating ambient temperature range VLN typ. Iline Iline ICC typ. Ip Ip typ. typ. YOUWANG ELECTRONICS CO.LTD 11 to 140 mA 1 to 11 mA 1mA 1.8mA 0.7mA 44 to 52 dB 20 to 39 dB AVD AVD AVD Vexch Rexch Tamb 3.8 V Typ. 6 dB 36 to 60V 400 to 1000Ω -25 to +75°C 1 UTC1062 LINEAR INTEGRATED CIRCUIT VCC 13 LN 1 5 GAR IR 10 4 OR 2 GAS1 MIC+ 7 MIC- 6 3 GAS2 dB DTMF 11 MUTE 12 SUPPLY AND REFERENCE CONTROL CURRENT LOW VOLTAGE CIRCUIT CURRENT REFERENCE 9 VEE 14 REG 15 AGC 8 STAB 16 SLPE Fig.1 Block Diagram LN 1 16 SLPE GAS1 2 15 AGC GAS2 3 14 REG OR 4 13 VCC GAR 5 12 MUTE MIC- 6 11 DTMF MIC+ 7 10 IR STAB 8 9 VEE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 LN GAS1 GAS2 OR GAR MICMIC+ STAB VEE IR DTMF MUTE Vcc REG AGC SLPE positive line terminal gain adjustment; transmitting amplifier gain adjustment; transmitting amplifier non-inverting output, receiving amplifier gain adjustment; receiving amplifier inverting microphone input non-inverting microphone input current stabilizer negative line terminal receiving amplifier input dual-tone multi-frequency input mute input positive supply decoupling voltage regulator decoupling automatic gain control input slope (DC resistance) adjustment Fig.2 Pining Diagram YOUWANG ELECTRONICS CO.LTD 2 UTC1062 LINEAR INTEGRATED CIRCUIT RATING LIMITING VALUES (In accordance with the Absolute Maximum System) parameter conditions Positive continuous line voltage Repetitive line voltage during switch-on or line interruption Repetitive peak line voltage for a 1 ms pulse/5s symbol min. － － VLN VLN R10=13Ω R9=20Ω (see Fig.15) R9=20Ω － － － － － － max. unit 12 V 13.2 V 28 V VLN Iline 140 mA VCC 0.7 Vi V Vi 0.7 V R9=20Ω Total power dissipation(2) Ptot 640 mW 40 125 °C Storage temperature range Tstg 25 75 °C Operating ambient temperature range Tamb 125 °C Junction temperature Tj 1. Mostly dependent on the maximum required Tamb and the voltage between LN and SLPE (see Figs 6 ). 2. Calculated for the maximum ambient temperature specified Tamb=75 °C and a maximum junction temperature of 125°C. Line current (1) Voltage on all other pins － + ＋ ＋ ＋ THERMAL RESISTANCE From junction to ambient in free air Rth j-a = 75K/W ELECTRONICAL CHARACTERISTICS (Iline=11 to 140mA;VEE=0V;f=800Hz;Tamb=25°C;unless otherwise specified) parameter Supply; LN and VCC(pins 1 and 13) Voltage drop over circuit, between LN and VEE Variation with temperature Voltage drop over circuit, between LN and VEE with external resistor RVA Supply current Supply voltage available for peripheral circuitry conditions MIC inputs open Iline=1mA Iline=4mA Iline=15mA Iline=100mA Iline=140mA Iline=15mA symbol VLN VLN VLN VLN VLN ∆VLN/∆T Iline=15mA RVA(LN to REG) =68kΩ Iline=15mA RVA(REG to SLPE) =39kΩ VCC=2.8V ICC Iline=15mA MUTE=HIGH Ip=1.2mA lp=0mA VCC VCC min. － － 3.55 4.9 1.6 1.9 4.0 5.7 － － 2.2 － max. － － unit － V V V V V mV/K 3.5 － V 4.5 － V 0.9 1.35 mA 2.7 3.4 － － V V － － － －0.3 － YOUWANG ELECTRONICS CO.LTD typ. 4.25 6.5 7.5 3 UTC1062 LINEAR INTEGRATED CIRCUIT ELECTRONICAL CHARACTERISTICS (continued) parameter Microphone inputs MIC+ and MIC(pins6 and 7) Input impedance (differential) between MIC- and MIC+ Input impedance (sigle-ended) MIC- or MIC+ to VEE Common mode rejection ratio Voltage gain MIC+ or MIC- to LN Gain variation with frequency at f=300Hz and f=3400Hz Gain variation with temperature At 25°C and +75°C - conditions symbol Zi kCMR － － － Iline=15mA R7=68kΩ Gv w.r.t.800Hz w.r.t.25°C without R6; Iline=50mA Gain variation with frequency at f=300Hz and f=3400Hz Gain variation with temperature At 25°C and +75°C - Noise output voltage unit 50.5 52.0 53.5 dB ∆Gvf － ±0.2 － dB ∆GvT － ±0.2 － dB 64 kΩ kΩ dB Zi － 20.7 － kΩ Iline=15mA R7=68kΩ Gv 24.0 25.5 27.0 dB w.r.t.800Hz ∆Gvf － ±0.2 － dB w.r.t.25°C Iline=50mA ∆GvT － ±0.2 － dB ∆Gv -8 － 0 dB VLN(rms) 1.7 2.3 VLN(rms) － 0.8 Iline=15mA THD=10% Iline=4mA THD=10% Iline=15mA; R7=68kΩ; 200Ω between MIC- and MIC+; psophometrically weighted VNO(rms) Receiving amplifier input IR (pin10) Input impedance max. 32 82 Gain adjustment GAS1 and GAS2 (pin2 and 3) Gain variation of the transmitting amplifier by varying R7 between GAS1 and GAS2 Sending amplifier output LN(pin 1) Output voltage typ. － － － Zi Dual-tone multi-frequency input DTMF (pin 11) Input impedance Voltage gain from DTMF to LN min. Zi YOUWANG ELECTRONICS CO.LTD － － -69 21 － － － － V V dB kΩ 4 UTC1062 LINEAR INTEGRATED CIRCUIT ELECTRONICAL CHARACTERISTICS (continued) parameter Receiving amplifier output OR (pin4) Output impedance Voltage gain from IR to OR Gain variation with frequency at f=300Hz and f=3400Hz Gain variation with temperature At 25°C and +75°C - Output voltage Output voltage Noise output voltage conditions Iline=15mA; RL(from pin 9 to pin 4 )=300Ω w.r.t.800Hz w.r.t.25°C without R6 Iline=50mA sine wave drive; Ip=0mA;THD=2% R4=100kΩ Iline=15mA RL=150Ω RL=450Ω THD=10% R4=100kΩ RL=150Ω Iline=4mA Iline=15mA R4=100kΩ IR open-circuit psophometrically weighted RL=300Ω symbol min. typ. max. unit Zo － 4 － Ω Gv 29.5 31 32.5 dB ∆Gvf － ±0.2 － dB ∆GvT － ±0.2 － dB VO(rms) VO(rms) 0.22 0.3 0.33 0.48 － － V V VO(rms) － 15 － mV VNO(rms) － 50 － µV ∆Gv －11 0 dB V V µA Gain adjustment GAR(pin 5) Gain variation of receiving amplifier achievable by varying R4 between GAR and OR MUTE input (pin 12) Input voltage(HIGH) Input voltage(LOW) Input current VIH VIL 8 VCC 0.3 15 ∆Gv － － － 70 － dB Gv － -19 － dB － -5.8 － dB IMUTE Reduction of gain - MIC+ or MIC to OR Voltage gain from DTMF to OR MUTE=HIGH MUTE=HIGH R4=100kΩ RL=300Ω Automatic gain control input AGC pin(15) Controlling the gain from lR to OR and the gain from MIC+/MICto LN;R6 between AGC and VEE Gain control range R6=110kΩ Iline=70mA 1.5 － － － ∆Gv YOUWANG ELECTRONICS CO.LTD 5 UTC1062 LINEAR INTEGRATED CIRCUIT ELECTRONICAL CHARACTERISTICS (continued) parameter conditions Highest line current for maximum gain Minimum line current for minimum gain symbol Iline Iline min. － － typ. 23 61 max. － － unit mA mA FUNCTIONAL DESCRIPTION Supply: VCC,LN,SLPE,REG and STAB Power for the UTC1062 and its peripheral circuits is usually obtained from the telephone line. The IC supply voltage is derived from the line via a dropping resistor and regulated by the UTC1062,The supply voltage Vcc may also be used to supply external circuits e.g. dialing and control circuits. Decoupling of the supply voltage is performed by a capacitor between Vcc and VEE while the internal voltage regulator is decoupled by a capacitor between REG and VEE. The DC current drawn by the device will vary in accordance with varying values of the exchange voltage(Vexch), the feeding bridge resistance(Rexch) and the DC resistance of the telephone line(Rline). The UTC1062 has an internal current stabilizer operating at a level determined by a 3.6kΩ resistor connected between STAB and VEE( see Fig.8). When the line current(Iline) is more than 0.5 mA greater than the sum of the IC supply current ( Icc) and the current drawn by the peripheral circuitry connected to VCC(lp) the excess current is shunted to VEE via LN. The regulated voltage on the line terminal(VLN) can be calculated as: VLN=Vref+ISLPE*R9 or; VLN=Vref+[(Iline ICC 0.5*10-3A)-Ip]*R9 where: Vref is an internally generated temperature compensated reference voltage of 3.7V and R9 is an external resistor connected between SLPE and VEE. In normal use the value of R9 would be 20Ω. Changing the value of R9 will also affect microphone gain, DTMF gain, in control characteristics, ide-tone level, maximum output swing on LN and the dc characteristics(especially at the lower voltages). Under normal conditions, when ISLPE ICC+0.5mA +Ip, the static behavior of the circuit is that of a 3.7V regulator diode with an internal resistance equal to that of R9.In the audio frequency range the dynamic impedance is largely determined by R1.Fig.3 shows the equivalent impedance of the circuit. - - >= Microphone inputs(MIC+ and MIC-) and gain pins (GAS1 and GAS2) The UTC1062 has symmetrical inputs. Its input impedance is 64kΩ (2*32kΩ) and its voltage gain is typically 52 dB (when R7=68kΩ.see Fig.13). Dynamic, magnetic, piezoelectric or electret (with built-in FET source followers) can be used. Microphone arrangements are illustrated in Fig.10. The gain of the microphone amplifier can be adjusted between 44dB and 52dB to suit the sensitivity of the transducer in use. The gain is proportional to the value of R7 which is connected between GAS1 and GAS2. Stability is ensured by the external capacitors, C6 connected between GAS1 and SLPE and C8 connected between GAS1 and VEE. The value of C6 is 100pF but this may be increased to obtain a first-order low-pass filter. The value of C8 is 10 times the value of C6. The cut-off frequency corresponds to the time constant R7*C6. Mute input(MUTE) A HIGH level at MUTE enables DTMF input and inhabits the microphone inputs and the receiving amplifier inputs; a LOW level or an open circuit does the reverse. Switching the mute input will cause negligible click is at the telephone outputs and on the line. In case the line current drops below 6mA(parallel operation of more sets) the circuit is always in speech condition independent of the DC level applied to the MUTE input. YOUWANG ELECTRONICS CO.LTD 6 UTC1062 LINEAR INTEGRATED CIRCUIT Dual-tone multi-frequency input(DTMF) When the DTMF input is enabled dialing tones may be sent onto the line. The voltage gain from DTMF to LN is typically 25.5dB(when R7=68kΩ) and varies with R7 in the same way as the microphone gain. The signaling tones can be heard in the ear piece at a low level(confidence tone). Receiving Amplifier (IR,OR and GAR) The receiving amplifier has one input(IR) and a non-inverting output(OR). Ear piece arrangements are illustrated in Fig.11. The IR to OR gain is typically 31dB (when R4=100kΩ). It can be adjusted between 20 and 31dB to match the sensitivity of the transducer in use. The gain is set with the value of R4 which is connected between GAR and OR. The overall receive gain, between LN and OR, is calculated by substracting the anti-sidetone network attenuation (32dB) from the amplifier gain. Two external capacitors, C4 and C7, ensure stability. C4 is normally 100pF and C7 is 10 times the value of C4. The value of C4 may be increased to obtain a first-order low-pass filter. The cut-off frequency will depend on the time constant R4*C4. The output voltage of the receiving amplifier is specified for continuous-wave drive. The maximum output voltage will be higher under speech conditions where the peak to RMS ratio is higher. Automatic gain control input(AGC) Automatic line loss compensation is achieved by connecting a resistor(R6) between AGC and VEE. The automatic gain control varies the gain of the microphone amplifier and the receiving amplifier in accordance with the DC line current. The control range is 5.8dB which corresponds to a line length of 5km for a 0.5mm diameter twisted pair copper cable with a DC resistance of 176Ω/km and average attenuation of 1.2dB/km. Resistor R6 should be chosen in accordance with the exchange supply voltage and its feeding bridge resistance(see Fig.12 and Table 1). The ratio of start and stop currents of the AGC curve is independent of the value of R6. If no automatic line loss compensation is required the AGC may be left open-circuit. The amplifier, in this condition, will give their maximum specified gain. Side-tone suppression The anti-sidetone network, R1//Zline, R2, R3, R8, R9 and Zbal,(see Fig.4) suppresses the transmitted signal in the ear piece. Compensation is maximum when the following conditions are fulfilled: (a) R9*R2=R1[R3+(R8//Zbal)]; (b) [Zbal/(Zbal+R8)]=[Zline/(Zline+R1)]; If fixed values are chosen for R1, R2, R3 and R9 then condition(a) will always be fulfilled when R8/Zball R3. To obtain optimum side-tone suppression condition(b) has to be fulfilled which results in: Zbal=(R8/R1) Zline=k*Zline where k is a scale factor; k=(R8/R1). The scale factor (k), dependent on the value of R8, is chosen to meet following criteria: (a) Compatibility with a standard capacitor from the E6 or E12 range for Zbal, (b) Zbal//R8 R3 fulfilling condition (a) and thus ensuring correct anti-sidetone bridge operation, R9 to avoid influencing the transmitter gain. (c) Zbal+R8 In practice Zline varies considerably with the type and length. The value chosen for Zbal should therefore be for an average line length thus giving optimum setting for short or long lines. < ｜ ｜ ｜< ｜> Example The balance impedance Zbal at which the optimum suppression is present can be calculated by: Suppose Zline = 210Ω+(1265Ω//140nF) representing a 5km line of 0.5 mm diameter, copper, twisted pair cable matched to 600 (176Ω/km;38nF/km). When k=0.64 then R8=390Ω,Zbal=130Ω+(820Ω//220nF). At line currents below 9mA the internal reference voltage is automatically adjusted to a lower value(typically 1.6V at 1mA) This means that more sets can be operated in parallel with DC line voltages (excluding the polarity guard) down to an absolute minimum voltage of 1.6V. With line currents below 9mA the circuit has limited sending and receiving levels. The internal reference voltage can be adjusted by means of an external resistor(RVA). This resistor when connected between LN and REG will decrease the internal reference voltage and when connected between REG and SLPE will increase the internal reference voltage. Ω YOUWANG ELECTRONICS CO.LTD 7 UTC1062 LINEAR INTEGRATED CIRCUIT Current(Ip) available from VCC for peripheral circuits depends on the external components used. Fig.9 shows this current for VCC>2.2V. If MUTE is LOW when the receiving amplifier is driven the available current is further reduced. Current availability can be increased by connecting the supply IC(1081) in parallel with R1, as shown in Fig.16(c), or, by increasing the DC line voltage by means of an external resistor(RVA) connected between REG and SLPE.. LN Leq Rp R1 REG VCC C3 C1 Vref R9 4.7µF 100µF Rp=16.2kΩ 20Ω Leq=C3*R9*Rp VEE Fig.3 Equivalent impedance circuit The anti-sidetone network for the 1062 family shown in Fig.4 attenuates the signal received from the line by 32 dB before it enters the receiving amplifier. The attenuation is almost constant over the whole audio frequency range. Fig.5 shows a conventional Wheat stone bridge anti-sidetone circuit that can be used as an alternative. Both bridge types can be used with either resistive or complex set impedance. R1 R2 R1 Zline R2 Zline im VEE IR Rt R9 IR im R3 R8 VEE Rt R8 R9 RA Zbal SLPE Fig 4 Equivalent circuit of UTC1062 anti-sidetone bridge SLPE Fig 5 Equivalent circuit of an anti-sidetone network in a wheat stone bridge configuration YOUWANG ELECTRONICS CO.LTD 8 UTC1062 LINEAR INTEGRATED CIRCUIT Iline 150 (mA) 130 (1) 110 (2) 90 (3) 70 Tamb (4) ℃ 1068mW ℃ 934mW ℃ 800mW ℃ 666mW (1) 45 (2) 55 (3) 65 (4) 75 50 30 Ptot 2 4 6 8 10 12 VLN-VSLPE(V) Fig.6 UTC1062 safe operating area Iline Rline R1 ISLPE + 0.5mA VCC LN Rexch DC 0.5mA AC REG STAB SLPE C1 PERIPHERAL CIRCUITS VEE Vexch C3 R5 ISLPE R9 Fig.8 Supply arrangement YOUWANG ELECTRONICS CO.LTD 9 UTC1062 LINEAR INTEGRATED CIRCUIT 2.4 a Ip (mA) b 1.6 0.8 (a) Ip=2.1mA (b) Ip=1.7mA Iline=15mA at VLN=4V R1=620Ω and R9=20Ω 0 0 1 2 3 4 5 Vcc(V) Fig.9 Typical current Ip available from Vcc peripheral circuitry with Vcc>=2.2V. curve (a) is valid when the receiving amplifier is not driven or when MUTE =HIGH .curve(b) is valid when MUTE=LOW and the receiving amplifier is driven; Vo(rms)=150mV,RL=150Ω.The supply possibilities can be increased simply by setting the voltage drop over the circuit VLN to a high value by means of resistor RVA connected between REG and SLPE. 7 7 MIC+ VCC (1) 7 MIC+ 6 MIC- VEE 6 MIC- (a) MIC+ 13 6 9 (b) MIC- (c) (a) Magnetic or dynamic microphone. The resistor marked(1) may be connected to decrease the terminating impedance. (b) Electret microphone. (c) Piezoelectric microphone. Fig. 10 Alternative microphone arrangement YOUWANG ELECTRONICS CO.LTD 10 UTC1062 LINEAR INTEGRATED CIRCUIT (1) OR 4 OR 4 OR 4 VEE 9 VEE 9 (a) (2) VEE 9 (b) (c) (a) Dynamic ear piece. (b) Magnetic ear piece. The resistor marked(1) may be connected to prevent distortion(inductive load) (c) Piezoelectric ear piece. The ear piece marked(2) is required to increase the phase margin (capacitive load) Fig.11 Alternative receiver arrangement △Gv (dB) R6=∞ 0 -2 R9=20Ω (1) R6= 78.7kΩ -4 (1) (2) (3) (2) R6= 110kΩ -6 (3) R6= 140kΩ 0 20 40 60 80 100 120 140 Iline (mA) Fig.12 Variation of gain with line current, with R6 as a parameter. Rexch(Ω) 400 600 R6(kΩ) Vexch(V) 800 1000 36 100 78.7 × × 48 140 110 93.1 82 60 × × 120 102 Table 1 Values of resistor R6 for optimum line loss compensation, for various usual values of exchange supply voltage(Vexch) and exchange feeding bridge resistance(Rexch);R9=20Ω. YOUWANG ELECTRONICS CO.LTD 11 UTC1062 LINEAR INTEGRATED CIRCUIT R1 620Ω 13 10 IR VCC 7 MIC+ 100µF 1 LN 4 OR 6 MIC- C1 100µF GAR 5 GAS1 2 C7 1nF 11 DTMF 12 MUTE GAS2 3 VEE REG AGC STAB SLPE 10µF 9 C3 4.7µF Vi C4 100pF R4 100kΩ Vi 14 15 8 R7 68kΩ Vo 10 TO 140 mA C8 1nF C6 100pF 16 R6 R5 3.6kΩ RL 600Ω R9 20Ω Fig.13 Test circuit defining voltage gain of MIC+,MIC- and DTMF inputs. Voltage gain is defined as : GV=20*log(|VO/Vi|).For measuring the gain from MIC+ and MIC- the MUTE input should be LOW or opencircuit, for measuring the DTMF input MUTE should be HIGH .Inputs not under test should be open-circuit. R1=620Ω 100µF 1 13 VCC C2 LN 10 IR 7 MIC+ QR 4 GAR 5 6 MIC- C1 100µF 10µF C7 1nF Vi GAS2 3 MUTE VEE REG AGC STAB SLPE 9 16 C3 4.7µF C4 Vo 100pF 600Ω 10 TO 140 mA GAS1 2 11 DTMF 12 R4 100kΩ ZL 14 15 8 R7 68kΩ C8 1nF C6 100pF R6 R5 3.6kΩ R9 20Ω Fig.14 Test circuit for defining voltage gain of the receiving amplifier. Voltage gain is defined as: GV=20*log(|VO/Vi|). YOUWANG ELECTRONICS CO.LTD 12 UTC1062 LINEAR INTEGRATED CIRCUIT R1 620Ω R10 130Ω BZX79 C12 BAS11 (x2) Telephone Line R2 132kΩ C5 100nF 1 10 C1 100µF 13 VCC LN IR C2 4 BZW14 (x2) R4 R3 3.92kΩ OR C4 100pF DTMF UTCI062 5 GAR 7 C7 1nF 6 From dial and control circuits 12 MIC+ MUTE MICSLPE 16 GAS1 2 C6 100pF R8 390Ω GAS2 3 REG 14 AGC 15 R9 20Ω C8 1nF STAB VEE 8 9 R7 RVA(R16.R14) Zbal 11 R6 C3 4.7µF R5 3.6kΩ Fig.15 Typical application of the UTC1062 ,shown here with a piezoelectric ear piece and DTMF dialing. The bridge to the left ,the Zener diode and R10 limit the current into the circuit and the voltage across the circuit during line transients. Pulse dialing or register recall required a different protection arrangement. The DC line voltage can be set to a higher value by resistor RVA(REG to SLPE). LN DTMF CARDLE CONTRAT DTMF UTC1062 MUTE VEE TELEPHONE LINE VDD VCC dialling circuit M1 VSS DP/FL BSN254A Fig.16 Typical applications of the UTC1062 (simplified) The dashed lines show an optional flash ( register recall by timed loop break). YOUWANG ELECTRONICS CO.LTD 13