SM6802A

NIPPON PRECISION CIRCUITS INC.—8

FUNCTIONAL DESCRIPTION

Power-down (PDWN)

The device enters power-down mode when PDWN goes LOW. When powered-down, the outputs become high

impedance and the internal oscillation stops. In power-down mode, the MUTEN pin should be held LOW.

Mute (MUTEN)

Mute operation occurs when MUTEN goes LOW. In mute mode, the outputs become high impedance. During

mute operation, the protection circuit operation is disabled, but the outputs are protected against output short

circuits by their high impedance state. When power is applied, MUTEN should be held LOW for a short inter-

val, shown in the timing diagram below, to prevent pop noise from the speaker. Also, applying and releasing

mute operation after power is applied can occur at high speed without generating pop noise.

Note. VREF1 load capacitance = 1

µF

Protection Circuit

The protection circuit operates if there is an output short-circuit to the supply, short-circuit to ground, or other

excessive load abnormal condition lasting longer than approximately 1

µs. Normal operation resumes after

approximately 5 seconds. When the protection circuit becomes active, the outputs become high impedance.

PDWN

min. 40msec

MUTEN