KA3010D

CD-ROM PRODUCTS

6

MIC-99D001

January 1999

APPLICATION INFORMATION

1. MUTEM

•

When the mute pin #7 is open or the voltage of the mute pin #7 is below 0.5V, the mute circuit is activated so

that the output circuit will be muted.

•

When the voltage of the mute pin is above 2V, the mute circuit is stopped and the output circuit is operated

normally.

•

If the chip temperature rises above 175

°C, then the TSD (Thermal shutdown) circuit is activated and the output

circuit is muted.

2. TSD (THERMAL SHUTDOWN)

•

TSD circuit.

•

The base-emitter voltage of the TR, Q11 is designed to turn-on at below voltage.

•

When the chip temperature rises up to 175

°C, then the turn-on voltage of the Q11 would drop down to 460mV.

(Hysteresis: 25

°C) Hence, the Q11 would turn on so the output circuit will be muted.

Pin #7

Mute circuit

High

Turn-off

Low

Turn-on

Open

Turn-on

7

Output driver

bias

R11

R12

Q11

Output driver

bias