SC7422

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

REV:1.0

2006.11.13

Http: www.silan.com.cn

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MUTE

4.3

GND

Output Mode Control

The output mode of the SC7422 can be switched between the SE (Single-Ended) and BTL (Bridge-Tied Load)

mode. It is recommended to apply BTL mode to obtain more output power while driving the loud speaker. SE

mode can be set to shutdown some parts of amplifiers while driving the stereo headphone. Therefore, the

quiescent operation current is reduced.

POPO Noise Suppress

When an audio power amplifier with a single supply turns on, the POPO Noise can be heard. The reason is that

the output voltage of amplifier would take hundreds of milliseconds to increase from 0V to 1/2 Vcc.

This time is controlled by CB, the external capacitor of Bypass pin. As the CB was increasing, the time is longer,

so it is much better to suppress POPO noise. However, the charging and discharging time for the input or output

capacitors should be less than this time. Therefore, CB is related with the input or output capacitors. The values

of these capacitors are recommended in the typical application circuit.

Thermally protected

There is a thermally protected protection circuit in the SC7422. If the chip temperature is over 120

°C, the

protection circuit will start up to shutdown the output stages of audio power amplifier. The chip will return to the

normal operation, until the chip temperature falls to 80

°C.

Power Dissipation and Heat Sinking

When the load is a resistor, the maximum of average power dissipation for the SC7422 is calculated as follows:

Where Is is the operation current. For example, if the SC7422 drives the 4

load in 5V supply, the power

dissipation is 2.6W.