Video ICs
•Pin descriptions
Pin No.
Pin name, function and remarks
〈VCC REC + B〉
1
• Power supply for REC + B.
• Connect to VCC (pin 7).
Voltage
VCC
BA7746S / BA7746FS
Circuit diagram
—
〈REC TC〉
• REC + B time constant.
2
• Use to adjust the REC + B rise time using the C
value. The value of the built-in resistor is 20kΩ.
• The effect of current spikes when recording is
started is reduced
REC: 0.9V
PB: 0V
REC
20k
〈HSWP IN〉
3
• Pulse input for head switching.
• ch1: H, ch2: L
—
24k
〈EP / SP CTRL〉
• EP / SP mode control.
4
• In EP mode, the playback amplifier gain is set to
—
+ 5dB (Typ.).
• EP: H, SP: L
• Do not leave open circuit
〈PRE OUT〉
• Playback amplifier output.
• Open emitter output.
REC: 3.6V
5
• When there is a chance of oscillation due to
capacitive load, reduce the output current, or
PB: 1.9V
(RL: 1.8kΩ)
connect a resistor in series (approx. 390Ω).
• Avoid capacitive coupling with the playback input
〈VCA CTRL (PRE MUTE)〉
• VCA control.
6
• When the terminal is open (a C is required), the
playback amplifier gain is set to the Typ. value.
REC: 2.0V
PB: 2.0V
• The PRE MUTE function is made possible by
connection of a mute H signal to this
through a diode
40k
EP SP
30k
580
20k
MUTE H
3