BA7781K
BA7781K is Stereo microphone amplifier for camcorders manufactured by ROHM.
Features
- 1) Operates off a 3.0V to 5.25V power supply. 2) Automatic wind-noise rejection circuit. 3) Matrix circuit for stereo emphasis.
4) Automatic switching circuit for external microphones, built-in external monaural decision circuit, and input switch mode decision circuit.
- Block diagram
MTX OUT L PRE OUT L INV OUT L MTX IN L MODE 24 HPF IN L 18 WND 15d B DET NOR INV IN L 24 EXT IN L 25 EXT BG 26 INT IN L 27 GND REG GND 28 VREG 29
17 16 DET OUT 15 DET IN 14 BIAS BIAS VCC 13 VCC 12 LPF INV OUT
- +
13d B
+
- MIX
10d B
+
- BIAS INT IN R 30 RIPL 31
OUT L 11 LPF INV IN 10 MIX OUT 09 MIC MONO 08 OUT R
13d B NOR WND 06 MTX OUT R
EXT IN R 32 EXT 01 MODE 1 02 PRE OUT R 03 INV IN R 04 INV OUT R
+
- 05 MTX IN R
15d B
07 HPF IN R
Video ICs
- Absolute maximum ratings (Ta = 25°C)
Parameter Power supply voltage Power dissipation Operating temperature Storage temperature Symbol VCC Pd Topr Tstg Limits 7.0 400∗
- 10 ~ +70
- 55 ~ +125 Unit V m W °C °C
- Remended operating conditions (Ta = 25°C)
Parameter Power supply voltage Symbol VCCS Min. 3.0 Typ.
- Max. 5.25 Unit V
∗ Reduced by 4m W for each increase in Ta of 1°C over 25°C.
- Electrical characteristics (unless otherwise noted, Ta = 25°C and V
Parameter Current dissipation 1 Current dissipation 2 Preamplifier gain Output amplifier gain Distortion Maximum output voltage Output noise voltage Input switch separation Interchannel separation Internal microphone power supply voltage Input switch control voltage Symbol I INT IEXT VGPR VGOA THD Vom VNO CTI→E CTL←
→R
= 3.3V)
Unit m A m A d B d B % Vrms d BV d B d B V V V Conditions INT MIC IN, L / Rch No dissipation by mic EXT MIC IN, L / Rch No dissipation by mic 30 / 32pin→2pin GAIN 27 / 25pin→23pin GAIN 3 / 6 / 7pin→8pin GAIN 22 / 19 / 18pin→17pin GAIN INT / EXT, Vo = 300m Vrms, L / Rch∗2 INT / EXT MIC IN, L / Rch f = 1k Hz (distortion 1%∗2 ) INT / EXT, L / Rch, Rg = 1kΩ When gain is 28d B∗1 INT→EXT MIC IN, Rg = 1kΩ, L / Rch...
