TDA8922BJ View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

TDA8922BJ

2×50 W class-D power amplifier

Philips Electronics 

Philips Semiconductors

TDA8922B

2 × 50 W class-D power amplifier

The amplifier system can be switched in three operating modes with pin MODE:

• Standby mode; with a very low supply current

• Mute mode; the amplifiers are operational; but the audio signal at the output is

suppressed by disabling the VI-converter input stages

• Operating mode; the amplifiers fully are operational with output signal.

To ensure pop-noise free start-up the DC output offset voltage is applied gradually to the

output between Mute mode and Operating mode. The bias current setting of the VI

converters is related to the voltage on the MODE pin; in Mute mode the bias current

setting of the VI converters is zero (VI converters disabled) and in Operating mode the

bias current is at maximum. The time constant required to apply the DC output offset

voltage gradually between mute and operating can be generated via an RC-network on

the MODE pin. An example of a switching circuit for driving pin MODE is illustrated in

Figure 4. If the capacitor C is left out of the application the voltage on the MODE pin will

be applied with a much smaller time-constant, which might result in audible pop-noises

during start-up (depending on DC output offset voltage and used loudspeaker).

In order to fully charge the coupling capacitors at the inputs, the amplifier will remain

automatically in the Mute mode before switching to the Operating mode. A complete

overview of the start-up timing is given in Figure 5.

+5 V

standby/

mute

R

R

mute/on

Fig 4. Example of mode selection circuit.

MODE pin

C

SGND

001aab172

9397 750 13357

Preliminary data sheet

Rev. 01 — 1 October 2004

© Koninklijke Philips Electronics N.V. 2004. All rights reserved.

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