Multimedia ICs Microphone Amplifier BA7760 / BA7760F The BA7760 and BA7760F are dual microphone amplifiers designed for audio signal amplification. These are low noise amplifiers with a low -122dBV (typically) equivalent input noise voltage. Each IC has an internal mixer buffer amplifier for the mixing of signals from two channels. When used with the BA7725S or BA7725FS, the BA7726AS or BA7726AFS and BU9252S or BU9252F, these ICs simplify the configuration of digital echo systems with two inputs (for karaoke duets, for instance). Applications •Audio equipment with karaoke features, VCRs, LDs, etc. •1)Features Internal 2-channel low noise microphone amplifier. 2) Internal mixer buffer amplifier with mute function. 3) Available in 2 types of packages: DIP 14-pin or SOP 14-pin. •Absolute maximum ratings (Ta = 25°C) Parameter Symbol Limits Unit VCC 15 V Applied voltage Power dissipation BA7760 Pd BA7760F 600∗1 mW 450∗2 Operating temperature Topr – 25 ~ + 75 °C Storage temperature Tstg – 55 ~ + 125 °C ∗1 Unmounted. Reduced by – 6.0mW for each increase in Ta of 1°C over 25°C. ∗2 Unmounted. Reduced by – 4.5mW for each increase in Ta of 1°C over 25°C. •Recommended operating conditions Parameter Symbol Limits Unit Power supply voltage VCC 6 ~ 14 V 1 Multimedia ICs BA7760 / BA7760F 1 RIPPLE FILTER 3 MIC IN Ch1 ( + ) MIC IN Ch2 ( + ) 12 2 GND 4 MIC IN Ch1 ( – ) MIC IN Ch2 ( – ) 11 5 FILTER Ch1 7 MIX IN 6 MIC OUT Ch1 •Block diagram – MIC AMP CH 1 MIC AMP CH 2 + MIX BF + + – VCC 14 MUTE CTRL 13 FILTER Ch2 10 MIC OUT Ch2 9 MIX OUT 8 – •Pin descriptions Pin name Pin No. Pin type Function 1 RIPPLE FILTER Ripple filter 2 GND GND 3 MIC IN ( + ) Ch1 CH1 microphone amplifier input ( + ) Base (NPN) // 120kΩ 4 MIC IN ( – ) Ch1 CH1 microphone amplifier input ( – ) Base (NPN) 5 FILTER Ch1 CH1 microphone amplifier fc Base (NPN) ~ 450Ω 6 MIC OUT Ch1 CH1 microphone amplifier output Push-pull 7 MIX IN Mixer buffer input Base (NPN) // 65kΩ 8 MIX OUT Mixer buffer output Push-pull 9 MIC OUT Ch2 CH2 microphone amplifier output Push-pull 10 FILTER Ch2 CH2 microphone amplifier fc Base (NPN) ~ 450Ω 11 MIC IN ( + ) Ch2 CH2 microphone amplifier input ( – ) Base (NPN) 12 MIC IN ( – ) Ch2 CH2 microphone amplifier input ( + ) Base (NPN) // 120kΩ 13 MUTE CTRL Mute control Fig.1 14 VCC VCC Base (NPN) // 15kΩ — — ∗ “Parallel” and “series” respectively refer to parallel and series insertion. All figures are standard values. 2 Multimedia ICs BA7760 / BA7760F •Input / output circuits 40kΩ MUTE CTRL 13 Fig. 1 •Electrical characteristics (unless otherwise noted, Vcc = 12V, Ta = 25°C) Parameter Supply current Symbol Min. Typ. Max. Unit Conditions Iq 3.65 4.87 6.09 mA — 〈MIC AMP (GVC= 36dB, f = 1kHz)〉 Open loop voltage gain GVOM 55.0 Input conversion noise VnM — 65.0 — – 122 – 114 Distortion THDM — 0.008 0.1 % VIN = – 40dBV B.W. = 0.4 ~ 30kHz Maximum output level VomM 8.3 10.4 — dBV THD = 1% B.W. = 0.4 ~ 30kHz Input impedance ZinM 92 123 — kΩ Crosstalk CTM — Voltage gain GVB – 0.7 Output residual noise VnB — Distortion THDB — 0.002 0.07 % VIN = – 10dBV B.W. = 0.4 ~ 30kHz Maximum output level VOMB 8.3 10.5 — dBV THD = 1% B.W. = 0.4 ~ 30kHz Input impedance ZinB 50.0 66.5 — kΩ – 110 – 100 2.62 3.12 – 86 – 78 dB dBV dBV VIN = – 70dBV Rg = 2.2kΩ, DIN AUDIO VIN = – 40dBV, 100kΩAttenuation VIN = – 36dBV Rg = 2.2kΩ, DIN AUDIO 〈MIX BF (f = 1kHz)〉 Mute level Mute threshold voltage MTB — VTHMUTE 2.12 0 – 110 0.7 – 100 dB dBV dBV V VIN = – 10dBV Rg = 2.2kΩ, DIN AUDIO VIN = – 10dBV, 50kΩAttenuation VIN = – 10dBV, DIN AUDIO — 3 Multimedia ICs BA7760 / BA7760F •Measurement circuit + 10 – + 5kΩ MIC OUT Ch1 4.7µF 6 150pF MIC AMP Ch1 150pF 13.9kΩ 9 1MΩ 7 – MIC AMP Ch2 MIC OUT Ch2 10µF + 5 – 1MΩ 8 5kΩ + 13.9kΩ MIX OUT MIX BF MIX IN 2.2kΩ 10kΩ 470µF + 470µF + 11 4 220Ω 220Ω + 12 3 + + 47µF 4.7µF MIC IN Ch1 MIC IN Ch2 + 47µF 4.7µF 2.2kΩ MUTE CTRL 13 2 VCC 2.2kΩ 14 1 + 22µF BA7760 / F Fig. 2 operation (Refer to “Application Example”) •TheCircuit BA7760 and BA7760F are dual microphone ampli- (Note: The attached component numbers are those used in “Application Example.”) 60dB 40dB C C 20dB = = 0 15 0p F 0dB 180° – 20dB 0° 3 61 3 61 3 61 3 61 3 61 – 180° 1kHz 10kHz 100kHz 1MHz 10MHz 100MHz FREQUENCY : f (Hz) Characteristics when using standard components and standard constants Fig. 3 Microphone amplifier frequency characteristics 4 PHASE VOLTAGE GAIN : GV (dB) fiers. The audio signals from the microphones are input to pins 3 and 12. The gain at this time is determined by attached resistors R3 / R4 and R6 / R7. By attaching capacitors to pins 5 and 10, the microphone amplifiers can be given frequency characteristics like those shown below. Multimedia ICs BA7760 / BA7760F Output from these dual amplifiers is level-adjusted with an attached volume control (VR) and then input to pin 7 and mixed by the mixer buffer amplifier. The ON / OFF operation of the mixer buffer amplifier can be controlled with the signal input to pin 13 (MUTE CTRL). For DC loads, this volume control (VR) should be set above 4.5kΩ to assure proper performance of the IC’s internal driver. Mode Control signal Operation MUTE L Muted MUTE H Normal operation + + 10µF 22kΩ – 6 – + 150pF 1µF 5 + – R7 + + 220Ω 220Ω + + 3 12 47µF MICIN Ch1 4.7µF MICIN Ch2 47µF R4 4 11 5kΩ (VR) 12kΩ 10 MIC AMP Ch1 150pF 12kΩ R6 MIC AMP Ch2 9 1µF + + 5kΩ (VR) 7 R3 MIXOUT MIX BF 8 0.1µF 10kΩ 0.1µF 22kΩ •Application example 4.7µF 2.2kΩ MUTE CTRL 2 14 1 + 13 VCC 2.2kΩ 22µF BA7760 / F Fig. 4 5 Multimedia ICs BA7760 / BA7760F •External dimensions (Units: mm) BA7760 BA7760F 19.4 ± 0.3 8.7 ± 0.2 8 3.2 ± 0.2 0.3 ± 0.1 2.54 0.5 ± 0.1 DIP14 6 14 8 1 7 1.27 0.15 ± 0.1 4.4 ± 0.2 6.2 ± 0.3 7.62 1.5 ± 0.1 7 0.51Min. 4.25 ± 0.3 1 0.11 6.5 ± 0.3 14 0.4 ± 0.1 0.3Min. 0° ~ 15° 0.15 SOP14