5

Video ICs

BA7746S / BA7746FS

13

REC: 0V

PB: 0V

14

REC: 0.58V

PB: 0V

15

REC: 4.1V

PB: 0V

16

GND

—

17

REC: 0V

PB: 0.8V

18

REC: 0V

PB: 0.7V

Pin No.

Pin name, function and remarks

Voltage

Circuit diagram

〈REC AGC FILTER〉

•

REC AGC filter.

•

The attack characteristics of the recording amplifier

can be adjusted using the CR circuit.

•

Reduce the CR circuit GND-side impedance to

improve the common-mode distortion.

〈REC CURRENT SENSE〉

•

Terminal for monitoring the recording current.

•

Open emitter output.

•

The REC AGC output current can be adjusted with

the R value.

e.g. 12

〈REC OUT〉

•

Recording amplifier output and head switch.

•

Open collector output.

•

The head switch turns on and off in accordance with

the REC / PB control signal

〈MAIN GND〉

•

Earth for circuits other than the preamplifier.

•

Reference potential for the IC

〈PRE AC-FB ch1〉

•

AC feedback terminal for the playback amplifier

(ch1).

•

The high-frequency characteristics of the playback

amplifier can be adjusted with the R value

〈PRE IN ch1〉

•

Input terminal for the playback amplifier (ch1).

•

The low-frequency cutoff characteristics can be

adjusted with the value of the input coupling

capacitor.

•

The frequency characteristics can be adjusted so

that it is flat with the L value of the rotary

transformer, and the external capacitor C (100pF

etc.).

2k

2k

14

15

17

18

4k

13k