BA3308FV datasheet(5/8 Pages) ROHM

5 / 8 page

197

Audio ICs

BA3308 / BA3308F / BA3308FV

(2)

Playback (See Fig. 7)

During playback, the ch1 and ch2 amplifiers are used as

NAB equalizer amplifiers, and time constant circuits are

connected between pins 1 and 3, and 7 and 9 in the nega-

tive-feedback section to give the NAB characteristics.

The voltage gain is given by:

GV =

 R11

) R9/ (I ) jϖC9 S R9)  /R3

In the same way as for recording, the NAB time constant

circuit is adjusted to give the required gain (to prevent

generation of a “pop” noise when power is applied). The

output stage (pins 3 and 7) operating point is fixed at 3VF.

Therefore, as indicated in the VMax. vs, VCC characteristic

(see Fig. 19), even if the VCC voltage is made larger than

5V, the maximum output voltage will not exceed 1.2V

(typ.). The ALC circuit is not required for playback, so pin

5 is grounded. The S / N ratio during playback is better if

the external resistors R1 and R2 that are connected to the

input pins (2 and 8) for recording are switched out.

BA3308FV Datasheet(PDF) 5 Page - Rohm