Transcript
Video ICs
VCR standard audio signal processor BA7797F The BA7797F is standard audio signal processor designed for use in VCRs and tape decks. The circuit is comprised of a playback preamplifier, a line amplifier, a recording amplifier, an ALC circuit and high-voltage head switch. The IC has a built-in coil equivalent circuit for recording equalization, which eliminates the need for an external component. Applications •Video cassette recorders and tape decks
•1)Features Two input switching systems built-in (LINE and TUNER). 2) Built-in coil equivalent circuit for recording equalization. 3) High-performance low-noise playback amplifier.
4) ALC level can be adjusted by connection of an external resistor. 5) Compatible with single-mode EQ making it ideally suited to widely-used decks.
REC HEAD SW
2
REC OUT
3 REC AMP 4
VCC
5
GND
17
PB NFB
16
PB OUT
15
PB LINE IN
14
ALC FILTER
13
TUNER IN
12
PB / TU / LINE CTRL
11
LINE IN
10
MUTE CTRL
+ 28dB
EQ REC L
18
PB
1
REC
PB IN
REC
•Block diagram
LINE
0dB
ALC
REC / EE CTRL
7
LINE OUT
8
ALC LEVEL ADJ
9
ATT – 8dB
MUTE
6
BUFF
RIPPLE FILTER
ATT – 8dB
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Video ICs
BA7797F
•Absolute maximum ratings (Ta = 25°C) Parameter
Symbol
Limits
Unit
VCC
13
V
Pd
550∗
mW
Operating temperature
Topr
– 10 ~ + 65
°C
Storage temperature
Tstg
– 55 ~ + 125
°C
Power supply voltage Power dissipation
∗ When mounted on a 50mm × 50mm × 1.6mm glass epoxy board. Reduced by 5.5mW for each increase in Ta of 1°C over 25°C.
•Recommended operating conditions (Ta = 25°C) Parameter
Symbol
Min.
Typ.
Max.
Unit
VCC
7.5
—
12.5
V
Power supply voltage
•Pin descriptions (V
CC
= 10V)
Pin No.
Pin name
Function
1
PB IN
Playback amplifier input / playback head switch
2.0V
REC: 120kΩ REC: 11Ω
2
REC HEAD SW
High-withstanding voltage recording head switch
0.0V
REC: 17Ω (ON) REC: OPEN
3
REC OUT
Recording amplifier output
4.7V
EF (P-P)
4
REC L
Recording EQ switch
4.7V
B (NPN)
5
VCC
VCC
10.0V
—
6
RIPPLE FILTER
Ripple filter
10.0V
10kΩ (VCC)
7
REC / EE CTRL
REC / EE control
8
LINE OUT
Line amplifier output
4.7V
EF (P-P)
9
ALC LEVEL ADJ
ALC level adjustment
4.1V
See Fig. 4
10
MUTE CTRL
11
LINE IN
12
PB / TU / LINE CTRL
13
TUNER IN
14
ALC FILTER
For setting the time constant for the ALC filter (attack and recovery times)
15
PB LINE IN
Line input for playback
4.7V
120kΩ
16
PB OUT
Playback amplifier output
2.0V
EF (P-P)
17
PB NFB
Playback amplifier feedback
2.0V
B (NPN)
18
GND
GND
0.0V
Mute control Line input PB / TU / LINE control Tuner input
∗ EF: emitter follower, P-P: push pull, B: base, and C: collector.
Pin voltage
—
— 4.7V — 4.7V PB: 0.0V PB: Not fixed
All measurements made using the measurement circuit (Fig.1) with VCC = 10V and quiescent circuit conditions. All numerical values are standardized values.
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I / O circuit
See input / output circuit
See input / output circuit 120kΩ See input / output circuit 120kΩ EF (NPN) ~ 100Ω
—
Video ICs
BA7797F
•Input / output circuits REC / EE CTRL 7
MUTE CTRL 10
REC / EE CTRL 7
MUTE CTRL 10
56kΩ H
56kΩ M
L
REC AMP
PB HEAD SW
PB / TU / LINE CTRL 12
H L
PB / TU / LINE CTRL 56kΩ 12
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Video ICs
BA7797F
•Electrical characteristics (unless otherwise noted, Ta = 25°C, V
CC
Parameter
= 10V, and f = 1kHz) Conditions
Measurement circuit
Symbol
Min.
Typ.
Max.
Unit
Quiescent current EE
IqEE
6.4
8.5
11.3
mA
No signal
Fig.1
Quiescent current PB
IqPB
6.4
8.5
11.3
mA
No signal
Fig.1
Quiescent current REC
IqREC
5.2
6.9
9.2
mA
No signal
Fig.1
〈Line amplifier〉 Voltage gain (PB input)
GVCLP
27.0
28.0
29.0
dB
VO = – 8dBV
Fig.1
Voltage gain (LINE1, LINE2, TU inputs)
GVCLT
19.0
20.0
21.0
dB
VO = – 8dBV
Fig.1
Distortion
THDLT
—
0.1
0.3
%
VO = – 8dBV, RL = 4.7kΩ∗
Fig.1
Maximum output level
VOMLT
5.9
8.4
—
dBV
THD = 1%, RL = 4.7kΩ∗
Fig.1
Output residual noise
VNOLT
—
– 81.5
– 75
dBV
Rg = 4.7kΩ, DIN AUDIO
Fig.1
– 9.0
– 8.0
– 7.0
dBV
VIN = – 25dBV, 9pin: OPEN
Fig.1
= – 25dBV, RL = 4.7kΩ∗
Fig.1
ALC level ALC distortion
VOA THDA
—
0.1
0.5
%
VIN
MT
—
– 82.0
– 72
dB
VO = 0dBV, DIN AUDIO
Fig.1
Voltage gain
GVCR
19.0
20.0
21.0
dB
LINE IN, TUNER IN→REC OUT
Fig.1
Distortion
THDR
—
0.13
0.4
%
VO = – 8dBV
Fig.1
Maximum output level
VOMR
5.7
8.2
—
dBV
VO = – 8dBV, RL = 4.7kΩ∗
Fig.1
Openloop gain
GVOR
60
71
—
dB
THD = 1%, RL = 4.7kΩ∗
Fig.1
Openloop gain
GVOP
61
68
—
dB
Input conversion noise
VNINP
—
Voltage gain (stand alone)
GVCP
35.0
36.0
37.0
dB
PB head switch impedance
RPH
—
11
20
Ω
Fig.1
REC head switch impedance
RRH
—
17
25
Ω
Fig.1
—
0
10
µA
E2 = ± 55V
Fig.1
80
100
—
VP-P
f = 70kHz, V2 ⬉ ± 1.5V
Fig.2
Mute attenuation ratio 〈Recording amplifier〉
Playback preamplifier – 122.5 – 114
dBV
Fig.1 Rg = 680Ω, DIN AUDIO
Fig.1
PB IN→PB OUT
Fig.1
〈Head switch〉
REC head switch DC withstanding voltage BVRHDC REC head switch AC withstanding voltage BVRHAC
∗ Measured at BW = 400Hz to 30kHz.
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Video ICs
BA7797F
3.3µ
•Measurement circuits 680
REC AMP EQ 0dB
+ 28dB LINE
0.01µ
330k
4.7µ
15
4.7k
PB LINE IN 47k
22µ
+
5
+
8
4.7k
13
12
ATT – 8dB
TUNER IN
47k PB / TU / LINE CTRL 4.7k
0.1µ
BUFF
4.7µ
7
MUTE
+
REC / EE CTRL
ATT – 8dB
0.1µ
ALC 6
ON: ALC OFF
2.2M
14
22µ
+
33µ
4.7k
0.1µ
12k 4
VCC
LINE OUT
PB OUT
16 +
6000p
3
1800p
1.5k
12k
4.7µ +
4.7k
+
17 PB
2
REC
REC HEAD SW REC OUT
18 22µ
1
330
+
PB IN
ON: Gvo PB REC
68k
11
LINE IN 47k
4.7k 9
MUTE CTRL
10
Units: R [Ω] C [F]
Fig.1
1
SW2 3
REC
2
PB IN
REC OUT
0.1µ
V ~
BVRHAC
100k
100k
1k
e2 V2 V
0.1µ
REC head switch AC withstanding voltage measurement circuit Fig. 2
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Video ICs
BA7797F
•Control mode table (1) REC / EE control, PB / TU / LINE control Control pins REC / EE
PB / TU / LINE
L
L
L
Function
Mode
PB HSW
REC HSW
LINE SW
REC AMP
LINE
OFF
ON
LINE
OFF
M
TUNER
OFF
ON
TUNER
OFF
L
H
PB
OFF
ON
PB
OFF
H
L
LINE REC
ON
OFF
LINE
ON
H
M
TU REC
ON
OFF
TUNER
ON
H
H
inhibit
—
—
—
—
If REC / EE CTRL is set to "M", the REC pause state is possible (REC head switch: open, REC amplifier: off).
(2) Mute control Control pins
Function
Mode
MUTE
LINE SW
H
MUTE
OPEN
L
MUTE
CLOSE
330k
LINE
15
22µ
12k
8.2k
+ 28dB
EQ CTRL +
4
16 REC AMP EQ 0dB
0.1µ
+
3
EQ CTRL
0.01µ
17
PB
2
18
330
1
REC
3.3µ +
BIAS OSC
+
REC + B
REC
•Application example
5
7
+
8
MUTE
ATT – 8dB
9
11
10
TUNER IN
PB / TU / LINE CTRL
12
BUFF
LINE OUT
13
0.1µ
ATT – 8dB
6
0.1µ
+
REC / EE CTRL
RL
14 ALC
22µ
+
33µ
VCC
LINE IN
MUTE CTRL
ALC LEVEL ADJ
Units: R [Ω] C [F]
Fig.3
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Video ICs
BA7797F
notes •(1)Operation ALC level Set the ALC level in the range – 8dBV to 0dBV by connecting a resistor between pin 9 and GND.
VOA = =
1 2 1 2
VBIAS
4k VCC – 0.7 • 4k + 32k × R / (32k + R) 2 4k • • VBIAS 4k + 32k × R / (32k + R) •
ALC LEVEL ADJ
4k
9
ALC DET
32k
R
The formula for approximating the value of this resistor is as follows: When pin 9 is open, VOA is preset to – 8dBV (for VCC = 10V). Note that the supply voltage VCC has an effect.
Fig.4
VBIAS = VCC – 0.7 2 9pin Voltage =
32k × R / (32k + R) • VBIAS 4k + 32k × R / (32k + R)
(2) Mute signal Apply the mute signal shown below at power on and off. If the muting time is short, a “pop” sound will be audible, particularly when the power is switched on.
VCC
(H)
(H)
2 sec. Min.
MUTE CTRL
LINE OUT
Fig.5
Also, be certain to apply the mute signal when switching between PB / LINE / TU. In the case of LINE / TU switching, it is possible to suppress switching noise by applying a time constant to the signal, in which case it is not necessary to apply the mute signal. (3) Recording control Do not switch the PB and REC modes on together. This will cause faulty operation.
(4) Line output The line output can drive a load resistance of up to 2kΩ. Depending on the type of load, it can cause local oscillation (eg. large capacitive loads that draw large current), so caution is required. In particular, when there is a possibility that the line output will be connected to a shielded cable, or line cable, connect a resistor of about 1kΩ in series with the output so that the capacitive load is not directly coupled to the IC output terminal.
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Video ICs
BA7797F
•Electrical characteristic curves 60
+
GAIN: GV (dB)
–
PB
17
16 12k
330k
40 +
22µ 330
0.01µ
30
20
10
100
1k
10k
100k
1M
10M
10
8
6 VCC = 10V THD = 1% (BW = 0.4 ~ 30kHz) ALC OFF
4
2
LINE
GAIN GVR: (dB)
40
1800p 6000p + 1.5k 10µ
OUT
4.7k
30
20
10
100
1k
10k
100k
FREQUENCY: f (Hz)
Fig. 9 Gain vs. frequency (REC amplifier)
•External dimensions (Units: mm)
1
9
5.4 ± 0.2
10
1.27
0.4 ± 0.1
0.15 ± 0.1
1.8 ± 0.1
0.11
7.8 ± 0.3
11.2 ± 0.2 18
2k
5k
10k
Fig. 7 Line amplifier load drive characteristics
VCC = 10V Input: LINE IN Output: REC OUT
3
1k
LOAD RESISTANCE: RL (Ω)
50 12k
VOUT
0
100 200 500
Fig. 6 Gain vs. frequency (PB amplifier)
REC &EQ
10µ
RL
FREQUENCY: f (Hz)
4
+
0.3Min. 0.15
SOP18
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OUTPUT LEVEL: VOUT (dBV)
50
MAXIMUM OUTPUT LEVEL: Vom (dBV)
10
VCC = 10V VIN = – 60dBV
f = 1kHz Input: LINE IN Output: LINE OUT 00 VCC = 10V – 10 VCC = 8.58V
– 20
– 30 – 40
– 30
– 20
– 10
00
INPUT LEVEL: VIN (dBV)
Fig. 8 ALC input / output characteristics
