ROHM BA8400FV Datasheet

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

141

13

2

123

114

10

5

96

87

CTL OUT V

CC

FILTER

HysBIAS

AGC

MONI OUT

IN –

BIAS

RECHPB

RECIN

GND

CTL +

CTL –

RECPBGND

2

Video ICs BA8400FV

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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, IO = + 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 = 25°C)

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 = 25°C)

Parameter Symbol Limits Unit

Applied voltage V

CC 2.7 ~ 3.5 V

䊊Not designed for radiation resistance.

3

Video ICs BA8400FV

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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