Page 1
1
Video ICs
Switchless REC / PB amplifier for
standard audio signal processing
BA7757BK
The BA7757BK contains a playback equalizer amplifier, an REC / PB switch, a line amplifier, an ALC circuit with
built-in detector, a recording amplifier, an analog switch for input switching, and a logic control circuit for independent
switching of REC / EE, PR / EE, line mute and input.
The IC is easy to interface with control systems, and features low noise during mode switching and at power on / off.
The line amplifier and recording amplifire are directly connected internally, allowing construction of a high-performance audio signal processing circuit for VCRs using a minimum number of external components.
•
Features
1) All necessary switches for audio signal processing
are built-in.
· MIC / LINE input selector switch.
· EP / SP equalizer selector switch.
· Built-in head switch on the playback side of the
head for head switching for REC / PB, and a headswitch driver terminal provided on the recording
side.
· EE / PB and EE / REC selector switches (compatibility with after-recording mode (AFR) is possible).
· Line muting switch.
2) All control functions are independent, so interfacing
with the control system is simple.
3) Amplifiers required for audio recording and playback are provided on the IC.
4) Excellent S / N and distortion specifications through
use of high-level ALC VR.
5) The ALC level is set using a external resistor, and
variation due to temperature is extremely low.
6) Built-in ripple filter gives excellent ripple rejection.
7) Low noise generation when power is switched on
and off, and during control system switching.
8) The line output can directly drive earphone.
9) Few external parts required.
10) Available in a QFP32 package, for high-density
mounting.
11) Low power consumption.
Page 2
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Video ICs BA7757BK
•
Block diagram
81234567
32
25EP SW
PB NF
FILTER
SP SW
V
CC
Vreg
PB OUT
LINE REC IN
LINE PB IN
BIAS 1
(V
CC
/
2)
LINE NFB
N.C.
BIAS 2
ALC FILTER
AGC VR CTRL
ALC LEVEL
MUTE CTRL
1724 23 22 21 20 19 18
GND
PB IN
LINE / MIC INPUT CTRL
INPUT SW OUT
LINE IN
MIC IN
FREQ. COMPENSATION
GND
26
27
28
29
30
31
EP SW
EP / SP CTRL
REC NFB
EE / REC CTRL
REC OUT
EE / PB CTRL
– 24.4dB
39.2dB
HEAD SW CTRL
LINE OUT
16
15
14
13
12
11
REC
LINE
10
9
R
P
BF
BIAS
BIAS
ALC
PB
120kΩ
INPUT SW
Page 3
3
Video ICs BA7757BK
•
Absolute maximum ratings (Ta = 25°C)
Parameter Symbol Limits Unit
V
400
∗
2
mW
°C
°C
V
CC 8.0
∗
1
Pd
Topr
Tstg
– 10 ~ + 65
– 55 ~ + 125
Power supply voltage
Power dissipation
Operating temperature
Storage temperature
∗
1 When IC is stand alone.
∗
2 Reduced by 4mW for each increase in Ta of 1°C over 25°C.
•
Recommended operating conditions
Parameter Symbol Min. Typ. Max. Unit
V
CC 4.0 — 6.0 VPower supply voltage
•
Electrical characteristics (unless otherwise noted, Ta = 25°C, VCC = 5V, and f = 1kHz)
Parameter Symbol Min. Typ. Max. Unit Conditions
I
qSP — 7.0 9.8 mA
I
qEP — 8.0 11.2 mA
DISTN
EE — 0.06 0.2 %
V
OmL 0.75 1.1 — Vrms
VOA – 6.8 – 5 – 3.2 dBV VIN = – 15dBV
DISTN
A — 0.08 0.2 %
G
VR 39.1 40.8 42.5 dB
DISTN
R — 0.06 0.2 %
V
OmR 0.85 1.2 — Vrms
GVSW – 0.5 0 — dB VIN = – 14dBV
DISTN
SW — 0.002 0.1 %
Z
INM —75—k
Ω
V
Omsw 0.85 1.2 — Vrms
LINE IN ~ LINE OUT, VIN = – 25dBV
∗
1
DISTN = 1%
∗
1
VIN = – 15dBV
∗
1
VIN = – 25dBV
∗
1
DISTN = 1%
∗
1
VIN = – 14dBV
∗
1
DISTN = 1%
∗
1
Quiescent current (SP mode)
Quiescent current (EP mode)
〈Line amplifier〉
(LINE IN ~ LINE OUT)
Distortion
Maximum output level
ALC level
ALC distortion
〈Recording amplifier〉
(LINE IN ~ REC OUT)
Gain
Distortion
Maximum output level
〈Input switch〉
(MIC IN ~ SW OUT)
Gain
Distortion
Input resistance
Maximum output level
∗
1 Measured at BW = 0.4 to 30kHz.
No signal, EE and SP mode
No signal, EE and EP mode
V
IN = – 25dBV, input attenuation conversion
Page 4
4
Video ICs BA7757BK
•
Measurement circuit
81234567
25
V
CC
5.6k
12k
330k
ON
G
vope
220
33
µ
0.01
µ
33
µ
100
µ
1
µ
1
µ
56k
5.6k
5.6k
56k
1
µ
V
reg
1724 23 22 21 20 19 18
26
27
28
29
30
31
– 24.4dB
39.2dB
16
15
14
13
12
11
REC
LINE
10 A
9
R
P
BF
BIAS
BIAS
ALC
PB
120k
Ω
INPUT SW
1k
MIC
IN
LINE
(REC)
IN
PB
OUT
&
LINE
(PB) IN
1M
47
µ
22
µ
33
µ
10k
FADE OUT
/ FADE IN
CTRL
MUTE
CTRL
Units
R:
Ω
C: F
22k
ON
ALC OFF
N.C.
NP
32
10
µ
LINE
OUT
EE / PB
CTRL
EE / REC
CTRL
EP / SP
CTRL
ON
G
VOREC
51k
REC
OUT
ON
R
L
100
Ω
V
CC
10k
10k
100
1
µ
4.7
µ
2.7k
1k
LINE
IN
10k
INPUT
SW
OUT
INPUT
SW
CTRL
62k
PB IN
0.47
µ
0.47
µ
1
µ
4.7
µ
470p
6.2k
220p
Fig. 1
++
+
+
+
++
+
+
+
+ +
+
+
+
+
Page 5
5
Video ICs BA7757BK
•
Application example
MIC
IN
AC BIAS
OSC
1k 1k
LINE
IN
INPUT
SW
CTRL
AUDIO
HEAD
TP
TP
81234567
32
25
Vreg
1724 23 22 21 20 19 18
26
27
28
29
30
31
– 24.4dB
39.2dB
15
14
13
12
11
REC
LINE
10
9
R
P
BF
BIAS
BIAS
ALC
PB
120kΩ
INPUT SW
1M
47µ
22µ
33µ
10k
FADE OUT
/ FADE IN
CTRL
MUTE
CTRL
22k
N.C.
NP
VCC
33µ
0.47
µ 0.47µ 220p
LINE
OUT
VCC
EE / PB
CTRL
EE / REC
CTRL
EP / SP
CTRL
16
Fig. 2
+
+
+
+
+
+
+
+
+
+ +
Units
R:
Ω
C: F
•
External dimensions (Units: mm)
0.15
0.4 ± 0.1
24
17
16
9
8
1
25
32
7.0 ± 0.2
9.0 ± 0.3
7.0 ± 0.2
9.0 ± 0.3
0.4
0.05
1.45 ± 0.1
0.15 ± 0.1
0.8
QFP32
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