7

Video ICs

BA7795LS / BA7795FS

(3) Playback operation

The signal applied to PB IN is amplified by playback

equalizer amplifier. At this time, the REC HEAD switch

is switched on by a control signal to REC / EE, and the

potential on one side of the head is fixed at GND . The

playback equalizer amplifier gain and equalizer charac-

teristics are set externally. The playback level is set by

the resistor divider between PB OUT and the playback

line input, The signal to the playback line input passes

though the input switch, is amplified by 20dB in the line

amplifier, and is output to the output buffer (the voltage

gain is different to that for the LINE input and TUNER

input).

It is possible to switch between the input block head

equalizer resonance point and playback equalizer char-

acteristic using the EQ CTRL control signal.

The line output can be stopped by setting muting mode

on using the MUTE CTRL signal. The ALC circuit and

recording amplifier are stopped in playback mode.

Signal flow for playback operation

1

3

5

7

9

11

13

15

17

19

21

23

2

4

6

8

10

12

14

16

18

20

22

24

+

+

+

+

+

REC + B

22

µ

33

µ

22

µ

10

µ

0.1

µ

47

µ

0.01

µ

39k

ALC

LINE

3.3

µ

330k

330k

12k

8.2k

4.7k

4.7k

0.1

µ

REC

– 20dB

2.2M

4.7k

8.2k

15k

1.5k

10

µ

+ 28dB

0.1

µ

REC / EE CTRL

EQ CTRL

PB / TU / EE

CTRL

MUTE

CTRL

BIAS

OSC

LINE IN

TUNER IN

LINE OUT

BA7795LS

C [F]

Units: R [

Ω]

Fig. 4 Signal flow for playback