Hands-Free Interface; Buzzer Driver - LG -510W Service Manual

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3.14 Hands-free Interface

The audio out (VOUTAUXP and VOUTAUXN) to the hands-free kit consists of a pair of differential

signals from the AD6521 auxiliary outputs (#K9, #K6), which are tracked down the board to carkit

connector (CN3) at the base of the handset. The DC level of the signal is supplied to the

VOUTAUX pin. And the EXT_IN signal is then input to the VINAUXP (#H10) and VINAUXN

(#G10) of the AD6521.

The buzzer is a piezo-electric transducer, which is driven by a pulse-width- square wave from the

BUZ1 output of the AD6522. Q3 amplify the signal in order to achieve the specified loudness.

Figure 3-16. Buzzer Driver.

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3. TECHNICAL BRIEF

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