KA3012D

8

Application Information

1. MUTE

• When the voltage level of the mute pin is above 2V, the mute circuit is activated so that the output circuit will be

muted.

• When the mute pin #9 is open or the voltage of the mute pin #9 is below 0.5V, the mute circuit is deactivated and the output

circuit operates normally.

2. TSD (THERMAL SHUTDOWN)

• If the chip temperature rises above 175

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

muted.

circuit.

• The base-emitter voltage of the TR,Q11 is designed to turn-on at 460mA.

× R12 / (R11 + R12)=460mV

• When the chip temperature rises up to 175

°C, the turn-on voltage of the Q11 drops down to 460mV. (Hysteresis: 25°C) and

Q11 turns on so the output circuit is muted.

Pin #9

Mute circuit

High

Turn-on

Low

Turn-off

Open

Turn-off

9

Output driver

bias

R11

R12

Q11

Output driver

bias