1
Video ICs
CTL recording / playback amplifier
for VHS VCRs
BA8400FV
The BA8400FV is a CTL recording / playback amplifier developed for VHS VCRs. The playback amplifier has an
AGC circuit that can handle large input signal fluctuations, and a recording / playback switching circuit is provided to
allow high-speed switching.
Applications
VHS-format VCRs
Features
1) Can be operated off low power supply voltage (2.7V
to 3.5V).
2) Playback amplifier with AGC.
3) Fast switching between recording and playback.
Block diagram
SW
P
R
P
R
P
R
Ref
REC
AMP
AGC
AMP
DET
14
1
13
2
12
3
11
4
10
5
9
6
8
7
CTL OUT
V
CC
FILTER
HysBIAS
AGC
MONI OUT
IN
BIAS
RECHPB
RECIN
GND
CTL +
CTL
RECPBGND
2
Video ICs
BA8400FV
Pin descriptions
Pin No.
Pin name
Function
1
2
3
4
5
6
7
8
9
10
11
12
13
14
CTL OUT
(CTL pulse output)
RECHPB
(record / play switch)
RECIN
(REC CTL pulse input)
GND
CTL +
(CTL head "+" input)
CTL
(CTL head "" input)
RECPBGND
BIAS
(bias)
IN
(playback amplifier input)
MONIOUT
(playback amplifier output)
AGC
(AGC time constant)
HysBIAS
(hysteresis amplifier
center level)
FILTER
(high-frequency
noise filter)
V
CC
CTL pulse output.
High output level approx. V
CC
0.05V, I
O
= + 0.5mA
Low output level approx. 0.05V, I
O
= 0.5mA
Switch input pin for the record / playback amplifiers.
High input: REC mode
Low input: PB mode
Threshold voltage: approx. 1 / 2V
CC
CTL pulse input pin for recording.
Threshold voltage: approx. 1 / 2V
CC
Power, REC / PB SW, CTL output buffer ground pin.
Ground pin for the REC and playback amplifiers.
Feedback input pin for the playback amplifier.
Playback amplifier output monitor pin.
Output dynamic range is the DC level
Vf.
Set the time constant after considering the transient response of the playback
mode switching.
AGC detect level VdetAGC = 0.47V
CC
[V] (approx.)
Playback amplifier output amplitude VAGC = 2
(VdetAGC HysVcent) [V
P-P
]
Connection pin for the bypass capacitor for the hysteresis amplifier center level.
Connect a decoupling capacitor close to the pin.
Pin for connection of high-frequency noise filter for AGC amplifier output for
playback CTL pulse. Also, input pin for the hysteresis amplifier. Hysteresis
amplifier center voltage HysVcent = 0.27Vcc [V] approx.
High-side hysteresis width
HysVH = 0.367V
CC
HysVcent [V]
Low-side hysteresis width
HysVL = 0.173V
CC
HysVcent [V]
Bias pin for the playback amplifier.
Bias voltage: VIB8 = 0.15V
CC
+ 1.3V (approx.)
When recording: CTL head positive-side recording current.
When playing: input pin for the playback CTL pulse.
When recording: CTL head negative-side recording current.
When playing: bias pin for the playback CTL pulse input.
Absolute maximum ratings (Ta = 25C)
Parameter
Symbol
Limits
Unit
Power supply voltage
Power dissipation
Operating temperature
Storage temperature
V
CC
Pd
Topr
Tstg
8.0
450
25 ~ + 75
55 ~ + 125
V
mW
C
C
Reduced by 4.5mW for each increase in Ta of 1
C over 25
C.
Recommended operating conditions (Ta = 25C)
Parameter
Symbol
Limits
Unit
Applied voltage
V
CC
2.7 ~ 3.5
V
Not designed for radiation resistance.
3
Video ICs
BA8400FV
Input / output circuits
Vcc
1k
25k
30k
25k
CTLOUT
1
RECPB
2
Vcc
CTL +
5
CTL
6
30k
25k
2k
25k
RECIN
3
22k
4k
45k
30k
BIAS
8
Vcc
Vcc
Vcc
Vcc
Fig.1
Fig.2
Fig.3
Fig.5
Fig.4
4
Video ICs
BA8400FV
IN
9
MONIOUT
10
CTL +
22k
45k
30k
2k
1.7V
1.7V
100
5.6k
15.9k
19k
2.9k
2.9k
5.2k
14.1k
1k
100
4k
5
AGC
11
HysBIAS
12
FILTER
13
Vcc
Vcc
Vcc
Fig.6
Fig.7
Fig.8
5
Video ICs
BA8400FV
Parameter
Symbol
Min.
Typ.
Max.
Unit
Conditions
--
--
--
--
--
--
--
Circuit current
AGC amplifier
AGC amplifier gain
Input bias voltage
Pin 5 input resistance
AGC control sensitivity
Output amplitude
Hysteresis amplifier
Hysteresis width
CTLOUT output high level voltage
CTLOUT output low level voltage
REC amplifier
Recording current
Max. output high level voltage
Max. output low level voltage
Threshold voltage
Input resistance
REC / PB switch
Threshold voltage
REC to PB switching time
I
CC
GVagc
VIB8
Z
IN
5
AGC / V
VAGC
HysV
VOHP
VOLP
Irec
VOHR
VOLR
Vth3
Z
IN
3
Vth2
TR P
--
2.5
1.35
1.6
2
0.88
250
2.0
--
1.3
2.0
--
1.0
24
1.0
--
3.5
4.5
1.7
2.0
0
1.1
290
2.8
0.2
2.5
2.8
0.2
1.5
30
1.5
--
7.0
6.5
2.05
2.4
+ 2
1.32
330
--
1.0
3.7
--
1.0
2.0
36
2.0
100
mA
dB
V
k
dB
V
P-P
mV
V
V
mA
V
V
V
k
V
ms
No signal, CTLOUT: High
V
IN
= 0.15
1.0V
P-P
f = 300Hz, V
IN
= 300mV
P-P
I
O
= 0.5mA
I
O
= + 0.5mA
R
O
= 400 W
I
O
= 0.5mA
I
O
= + 0.5mA
See note below
Note: The switching time from REC to PB is the time until CTLOUT is output.
Electrical characteristics (unless otherwise noted, Ta = 25C and V
CC
= 3V)
6
Video ICs
BA8400FV
SW
P
R
P
R
P
R
Ref
+
+
+
REC
AMP
AGC
AMP
DET
14
V
CC
V
CC
1
13
2
12
3
11
4
10
5
9
6
8
7
A
Am14
SW13a
V
1000p
Vm13
270k
4.7k
1M
1
10
Vm10
SW10
12k
330k
820
910
+
+
V
V
+
V
+
a
b
a
b
SW9
10
1
Vm8
SW12
Vs13
SW13b
V
A
V
Is2
a
b
c
SW2
OSC
a
b
c
a
b
c
SW5
SW1
Am2
Am3
V
CC
A
V
Vm3
Vm1
Is1
Vm5
400
Am56
Vm6
a
b
c
Vs3
d
SW3
+
Is5
10
A
V
V
Fig.9
Measurement circuit
7
Video ICs
BA8400FV
Parameter
Symbol
Monitor
Notes
Switch position
SW
1
SW
2
SW
3
SW
5
SW
9
SW
10
SW
12
SW
13a
SW
13b
Circuit current
AGC amplifier
AGC amplifier gain
Input bias voltage
Pin 5 input resistance
AGC control sensitivity
Output amplitude
Hysteresis amplifier
Hysteresis width
CTLOUT output voltage H
CTLOUT output voltage L
REC amplifier
Recording current 5
Recording current 6
Max. output voltage "H"
Max. output voltage "L"
Input threshold voltage
Input resistance
REC / PB switch
Threshold voltage
REC to PB switching time
Am14
Vm13
Vm8
Vm5
13pin
13pin
Vm1
Vm1
Vm1
Am56
Am56
Vm1
Vm1
Vm3
Vm3
Vm2
1pin
a
a
a
a
a
a
a
c
c
a
a
c
c
a
a
a
a
a
a
a
b
a
a
a
a
a
b
b
b
b
b
b
c
ba
a
a
a
b
a
a
a
a
a
b
a
b
a
c
d
a
a
a
c
a
b
c
c
a
a
a
a
a
a
a
a
a
a
c
a
b
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
b
a
a
b
b
a
a
a
a
a
a
a
a
a
a
a
ON
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
b
b
b
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
--
--
--
--
--
--
1.
f = 300Hz,
V
IN
= 50mV
P-P
3.
f = 300Hz,
V
IN
= 0.15 / 1.0V
P-P
4.
f = 300Hz,
V
IN
= 300mV
P-P
2.
5.
I
O
= 0.5mA, Vs13 = 1.5V
I
O
= + 0.5mA, Vs13 = 0V
6.
6.
I
O
= 0.5mA
I
O
= + 0.5mA
I
CC
GVagc
VIB8
Z
IN
5
AGC / V
VAGC
HysV
VOHP
VOLP
Irec5
Irec6
VOHR
VOLR
Vth3
Z
IN
3
Vth2
TR-P
Measurement conditions (unless otherwise noted, Ta = 25C and V
CC
= 3V)
Measurement method
1 Input a sine wave of f = 300Hz to pin 5, and measure the output amplitudes on pins 10 and 13 (Vo10 and Vo13).
The AGC gain is given by: Gvagc = 20log (Vo13 / Vo10) [dB].
2 Measure the output voltages Vo0 and Vo.5 on pin 5 when currents of Is5 = 0, and Is5 = 0.5mA are applied.
The input resistance is given by: ZIN5 = {0.0005 / (Vo.5 Vo0) 1 / 400}
1
[
]
3 Input a sine wave of f = 300Hz to pin 5. Adjust the input level until the output amplitude on pin 10 is 0.15V
P-P
and 1.0V
P-P
, and measure the correspond-
ing output amplitudes on pin 13 (Vo0.15 and Vo1.0).
The AGC control sensitivity is given by:
AGC / V = 20log (Vo1.0 / Vo0.15) [dB].
4 Input a sine wave of f = 300Hz to pin 5. Adjust the input level until the output amplitude on pin 10 is 300mV
P-P
.
Measure the output amplitude on pin 13.
5 With pin 13 floating, measure the output voltage Vocent.
Increase Vs13 from 0V, and record V
IN
H as the Vs13 voltage when the pin 1 output exceeds 2.8V.
Decrease Vs13 from 1.5V, and record V
IN
L as the Vs13 voltage when the pin 1 output goes below 0.2V.
High-side hysteresis width
HysVH = V
IN
H Vocent [V
P-P
]
Low-side hysteresis width
HysVL = V
IN
L Vocent [V
P-P
]
6 Measure the currents I
IN
2.7 and I
IN
3.0 on pin 3 when voltages Vs3 of 2.7V and 3.0V respectively are applied.
The input resistance is given by: Z
IN
3 = 0.3 / (I
IN
3.0 I
IN
2.7) [
]
7 Input a square wave of 300Hz, V
IN
= 20mV
P-P
to pin 5, and measure the time that it takes CTLOUT to be output after pin 2 goes from V
CC
to 0V.
8
Video ICs
BA8400FV
SW
P
R
P
R
P
R
Ref
+
+
+
REC
AMP
AGC
AMP
DET
14
1
13
2
12
3
11
4
10
5
9
6
8
7
CTL OUT
V
CC
3.0V
FILTER
HysBIAS
AGC
MONI OUT
IN
BIAS
RECHPB
RECIN
GND
CTL +
CTL
RECPBGND
+
+
1
F
10
F
1M
910
+
1
F
330k
22
F
+
33
F
+
1000pF
Fig.10
Application example
9
Video ICs
BA8400FV
SSOP-B14
0.1
0.22
0.1
0.65
8
7
14
1
6.4
0.3
4.4
0.2
5.0
0.2
1.15
0.1
0.15
0.1
0.3Min.
0.1
External dimensions (Units: mm)
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