Service manual

STV8225 ( AM SIF Circuit )

(1) General Description

The STV8225 is intended for the demodulation of the AM sound of the L standard.

(2) Feature

•

sound AM synchronous demodulator

•

AM/FM audio switch and AV/TV audio switch

(3) Block Diagram

(4) Pin Description

PIN SYMBOL DESCRIPTION

1, 14 IF in IF input

2 AGC AGC capacitor

3 GND ground

4 level sw level switch of AF output voltage (pin7,9)

- open : 250 mVrms

- ground : 500 mVrms

5 FM in FM sound input

6 mute mute input

7 main in main sound input

8 n.c

9 ext out external sound output

10 sw in switching input

voltage mode connection

pin7 pin 9

2.3V below TV/FM A C

4.6V below TV/AM A A

6.8V below AV/AM B A

6.8V above AV/FM B C

11 ext in external sound input

12 Vcc supply voltage (+9V)

13 mean cap mean capacitor