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ROHM Semiconductor |
Video ICs
Stereo zoom microphone amplifier
for camcorders
BA7780KV
The BA7780KV is a microphone amplifier developed for use in camcorders. The IC features an electronic volume cir-
cuit for presetting the curve required for the stereo zoom function, a microphone element power supply regulator, a
wind-noise rejection filter, a current limiting circuit for external accessory power supplies, and an input for external
microphone input. The IC operates off a 3.3V power supply.
•Applications
Camcorders
•Features
1) Operates off a 3.0V to 5.25V power supply.
2) Zoom microphone processing function on one chip.
3) Built-in electronic volume for external setting of sen-
sitivity and control voltage.
4) Adjustable microphone element sensitivity.
5) Matrix amplifier for stereo emphasis.
6) Automatic switching circuit for external inputs, and
built-in external monaural decision circuit.
•Absolute maximum ratings (Ta = 25°C)
Parameter
Symbol
Power supply voltage
VCC
Power dissipation
Pd
Operating temperature
Topr
Storage temperature
Tstg
∗ Reduced by 7.5mW for each increase in Ta of 1°C over 25°C.
Limits
7.0
750∗
– 10 ~ + 70
– 55 ~ + 125
Unit
V
mW
°C
°C
•Recommended operating conditions (Ta = 25°C)
Parameter
Symbol Min. Typ.
Power supply voltage
VCCS 3.0 —
Max.
5.25
Unit
V
1
Video ICs
•Block diagram
BA7780KV
48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33
GND L 49
MIX1 IN L 50
13dB
GZ CONT 51
REC
EXT
INT
13dB
GC
–
+
INT: ON
32 OUT L
31 MIC MONO
30 Z B
SUB INV2 OUT 52
SUB INV2 IN 53 – +
SUB BUF2 OUT 54
RFLT
BALANCE
15dB
EXT
INT
5dB
29 Z A
28 Z SENSE
27 Z POINT
SUB VCA OUT 55
26 GAIN CONT
SUB VCA IN 56
MIX2 OUT 57
CImt
25 EX VCC OUT
24 EX VCC
SUB BUF2 IN 58
RFLT
23 VCC
SUB INV1 OUT 59
SUB BUF1 OUT 60
SUB BUF1 IN 61
BALANCE
5dB
INT
EXT
15dB
22 Z AC
21 Z BC
20 IN MONI
MIX1 OUT 62 MIX
MIX1 IN R 63
GND R 64
13dB
REG
INT
EXT
13dB
INT: 0N
+
GC –
19 HPF CONT
18 BIAS SUB
17 OUT R
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16
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