KA3012D Просмотр технического описания (PDF) - Fairchild Semiconductor

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производитель

KA3012D

4-Channel Motor Driver

Fairchild Semiconductor 

Application Information

1. MUTE

Pin #9

Mute circuit

High

Turn-on

Low

Turn-off

9

Open

Turn-off

KA3012D

Output driver

bias

• 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.

• When the mute circuit is activated, the voltage level of output pins becomes 1/2VCC (approximately).

2. TSD (THERMAL SHUTDOWN)

VREF BG

R11

Output driver

bias

Q11

R12

• If the chip temperature rises above 175°C, then the TSD (Thermal shutdown) circuit is activated and the output circuit is

muted.

• The VREF BG is the output voltage of the band-gap-referenced bias in circuit and acts as the input voltage of the TSD

circuit.

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

VBE = VREF BG × 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.

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