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Preliminary data sheet

Rev. 01 — 1 October 2004

5 of 32

Philips Semiconductors

TDA8922B

2

× 50 W class-D power amplifier

8.

Functional description

8.1 General

The TDA8922B is a two channel audio power amplifier using class-D technology.

The audio input signal is converted into a digital Pulse Width Modulated (PWM) signal via

an analog input stage and PWM modulator. To enable the output power transistors to be

driven, this digital PWM signal is applied to a control and handshake block and driver

circuits for both the high side and low side. In this way a level shift is performed from the

low power digital PWM signal (at logic levels) to a high power PWM signal which switches

between the main supply lines.

A 2nd-order low-pass filter converts the PWM signal to an analog audio signal across the

loudspeakers.

The TDA8922B one-chip class-D amplifier contains high power D-MOS switches, drivers,

timing and handshaking between the power switches and some control logic. For

protection a temperature sensor and a maximum current detector are built-in.

The two audio channels of the TDA8922B contain two PWMs, two analog feedback loops

and two differential input stages. It also contains circuits common to both channels such

as the oscillator, all reference sources, the mode functionality and a digital timing

manager.

The TDA8922B contains two independent amplifier channels with high output power, high

efficiency, low distortion and a low quiescent current. The amplifier channels can be

connected in the following configurations:

SGND1

11

5

signal ground for channel 1

12

6

negative analog supply voltage for channel 1

PROT

13

7

decoupling capacitor for protection (OCP)

14

8

positive power supply voltage for channel 1

BOOT1

15

9

bootstrap capacitor for channel 1

OUT1

16

10

PWM output from channel 1

17

11

negative power supply voltage for channel 1

STABI

18

12

decoupling of internal stabilizer for logic supply

n.c.

19

-

not connected

20

13

negative power supply voltage for channel 2

OUT2

21

14

PWM output from channel 2

BOOT2

22

15

bootstrap capacitor for channel 2

23

16

positive power supply voltage for channel 2

24

17

negative digital supply voltage

Table 3:

Symbol

Pin

Description

TDA8922BTH

TDA8922BJ