Compander IC MM1077 MITSUMI Compander IC Monolithic IC MM1077 Outline This IC was developed for use in cordless telephone equipment. It is a compander IC incorporating compressor/expander circuits for a significant noise reduction effect without complicated external circuitry. On the transmission side, the dynamic range of audio signals is compressed by the compressor circuit; on the receiving side, the expander expands the signals. As a result the dynamic range over the transmission channel is reduced logarithmically by one-half. Features 1. Can be driven at low voltages (down to 2.0V) 2. Internal mute function 3. Internal limiter (IDC) function 4. Compressor input can be switched between MIC and LINE 5. Internal standby function 6. Data input, output pins 7. Independent mute circuit Package SSOP-24A (MM1077XF) Applications 1. Cordless telephones 2. Various mobile communication devices Pin Assignment 24 23 22 21 20 19 18 17 16 15 14 13 1 2 3 4 5 6 7 8 9 10 11 12 SSOP-24A 1 C.Vref 9 DATA. IN 17 E.RECT 2 C.IN1 10 C.CONT 18 E.OUT 3 C.IN2 11 N.C 19 E.RIN 4 C.IN- 12 GND 20 A.OUT 5 C.RECT 13 STANDBY SW 21 A.IN- 6 C.RIN 14 C.IN SW 22 A.IN+ 7 C.FB 15 C.MUTE SW 23 E.Vref 8 C.NF 16 E.MUTE SW 24 Vcc Compander IC MM1077 MITSUMI Block Diagram Absolute Maximum Ratings (Ta=25°C) Item Symbol Ratings Units Storage temperature TSTG -40~+125 °C Operating temperature TOPR -10~+70 °C Power supply voltage VCC max. -0.3~+8 V Allowable loss Pd 650 mW +2.0~+7 V Operating voltage Compander IC MM1077 MITSUMI Electrical Characteristics (Except where noted otherwise, Ta=25°C, VCC=3V, fin=1kHz) Item Symbol Measurement conditions Consumption current ICC Standby current consumption Iscc Threshold voltage Vth Input reference level VINc 4.0 6.0 mA 0 10 µA 0.40 0.65 0.80 V Voc=100mVrms, VIN=0dB 8.0 13.5 18.0 mVrms Gc1 VIN=-20dB -0.5 0 0.5 dB Gc2 VIN=-40dB -1.0 0 1.0 dB Distortion THDc VIN=0dB 0.3 1.0 % Output noise voltage Vnc No signal (CCITT) 2.5 5.0 mVrms Mute attenuation Attc VIN=0dB, C.MUTE SW : ON 40 50 Limit voltage Vlimc THD=10% 700 800 900 mVp-p DATA pin voltage gain GDATA 0 0.5 dB Gain error Compressor unit Min. Typ. Max. Units * No signal C. MUTE SW : ON, VIN=0dB -0.5 VD max. C.MUTE SW : ON, THD=10% 800 DATA pin maximum output dB 900 mVrms Crosstalk CTc EXPVIN=0dB 28 33 dB Ripple rejection ratio RRc VR=100mVrms, fR=1kHz 18 23 dB Input reference level VINe Voe=100mVrms, VIN=0dB 25 35 50 mVrms Ge1 VIN=-10dB -0.5 0 0.5 dB Ge2 VIN=-20dB -1.0 0 1.0 dB Ge3 VIN=-30dB -1.5 0 1.5 dB Distortion THDe VIN=0dB 0.15 1.0 % Expander Maximum output voltage Ve max. THD=10% unit Output noise voltage Vne No signal (CCITT) Mute attenuation Atte VIN=0dB, C. MUTE SW : ON 60 70 Input amp voltage gain GI VIN=0dB 14.6 15.6 Input amp maximum output Veo max. THD=10% 0.90 1.10 Vrms Crosstalk CTe COMPVIN=0dB 60 75 dB Ripple rejection ratio RRe VR=100mVrms, fR=1kHz 50 60 dB Gain error difference * (dBv)+20dB) -V *Gain error difference = G(V : COMP=0.5, EXP=2 OUT IN (dB) 600 800 20 mVrms 40 µVrms dB 16.6 dB G (dB) Function Description 1. Compressor unit The compressor unit consists of the mike amp, compressor, limiter circuit, data amp, and mute circuit. The mike amp gain can be adjusted through an external resistance, and so the mike amp can be connected directly to a microphone. An internal limiter circuit to prevent overmodulation as well as a data amp (0dB amp) enabling transmission of data signals without compression are also provided. Switching between audio signals and data signals is possible using the compressor mute switch. 2. Expander unit The expander unit consists of an input amp, expander, and mute circuit. The input amp makes available all input and output signals at pins, and so can be used freely as an amplifier, filter amp, or data amp. When used as a data amp, the expander mute switch can be set so that the expander output is nearly silent. MITSUMI Compander IC MM1077 About Application Circuits 1. Mike amp The compressor unit mike amp is exposed to circuits outside the IC via positive and negative input pins. The positive input pin is connected to C.Vref by a bias resistance of 100kΩ, so that no external bias is needed. When pin 4 is open the gain is lowest, and an input voltage of approx. 13.5Vrms is the reference level. When the external resistance is 0Ω, the gain is maximum. The internal configuration appears in Fig. 1. 2. Rectifier circuit unit (rectifier) The product of the external capacitance and the internal resistance (10kΩ) determines the time constants for the attack and release times. 3. Compressor amp The compressor amp requires that the DC gain be unity and the AC gain be infinite. In order to satisfy this requirement, AC feedback is eliminated and only DC feedback is used. In order that only DC feedback be present, a capacitor to eliminate AC components is connected to pin 8. The cutoff frequency is determined by the product with the internal resistance (100kΩ). MITSUMI Compander IC MM1077 4. Compressor data amp The data amp uses an inverting amp. The internal input resistance is 100kΩ, and the DC bias voltage is 1.3V. The compressor mute switch at pin 15 is used to switch between data signals and audio signals. 5. Expander input amp The positive and negative input pins and the output pin are exposed to circuitry outside the IC. The expander input amp can be used as a signal amplifier, a buffer amplifier, and a filter amp. By taking the signal from this amp's output pin, the data signal can be obtained without passing through the expander. If the expander mute switch is turned on, this signal can be prevented from appearing in the expander output. 6. Mike amp input switch and mute switches The internal equivalent circuit for each of these switches appears in Fig. 6. 7. Standby switch The internal equivalent circuit for the standby switch appears in Fig. 7. Compander IC MM1077 MITSUMI Measuring Circuit (Except where noted otherwise, fIN=1kHz) 1. Consumption current 5. Distortion 2. Threshold voltage 6. Limit voltage 3. Input reference level 7. Maximum output voltage 4. Gain error difference 8. DATA pin/Input amp voltage gain Gain error difference= (VOUT (dBv) -20dB) -VIN (dB) (G=COMP=0.5, EXP=2) G Gain error difference (1) Gc1=-20dB, Ge1=-10dB Gain error difference (2) Gc2=-40dB, Ge2=-20dB Gain error difference (3) Ge3=-30dB Compander IC MM1077 MITSUMI 9. DATA pin/Input amp maximum output 12. Output noise voltage 10. Crosstalk 13. Mute attenuation 11. Ripple rejection