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AD1991

Class D/1-Bit Audio Power Output Stage

FUNCTIONAL BLOCK DIAGRAMS

2-Channel Mode

INA

INB

LEFT

INPUT

LEVEL SHIFTER

AND

SWITCH CONTROL

H-BRIDGE

AGND DGND

TEST

CONTROL

PGND

A1

A2

B1

B2

C1

C2

D1

D2

OUTA

3

OUTB

3

OUTC

3

OUTD

3

INC

IND

RIGHT

INPUT

CLK

RST/PDN

MUTE

CURRENT OVERLOAD

THERMAL SHUTDOWN

THERMAL WARNING

DATA LOSS

2

14

4

6

THERMAL PROTECTION

SHORT-CIRCUIT PROTECTION

MUTE CONTROL

n

4-Channel Mode

INA

INB

LEVEL SHIFTER

AND

SWITCH CONTROL

H-BRIDGE

AGND DGND

TEST

CONTROL

PGND

A1

A2

B1

B2

C1

C2

D1

D2

INC

IND

CLK

RST/PDN

MUTE

CURRENT OVERLOAD

THERMAL SHUTDOWN

THERMAL WARNING

DATA LOSS

2

4

14

6

THERMAL PROTECTION

SHORT-CIRCUIT PROTECTION

MUTE CONTROL

n

OUTA

3

LOAD

REQUIRING

DC VOLTAGE

SUPPLY

OUTD

3

LOAD

REQUIRING

DC VOLTAGE

SUPPLY

OUTB

3

OUTC

3

FEATURES

Class D/1-Bit Audio Power Output Stage

5 V Analog and Digital Supply Voltages

Power Stage Power Supply 8 V to 20 V

Output Power @ 0.1% THD + N

Stereo Mode

2

20 W @ 4

@ 14.4 V

2

20 W @ 8

@ 20 V

Mono Mode

1

40 W @ 4

@ 20 V

(per Transistor)

Efficiency > 85% @ Full Power/8

Clickless Mute Function

Turn-On and Turn-Off Pop Suppression

Short-Circuit Protection

Overtemperature Protection

Data Loss Protection

2-Channel BTL Outputs or

4-Channel Single-Ended Outputs

52-Lead Exposed Pad TQFP Package

Low Cost DMOS Process

APPLICATIONS

PC Audio Systems

Minicomponents

Automotive Amplifiers

Home Theater Systems

Televisions

GENERAL DESCRIPTION

The AD1991 is a 2-channel BTL or 4-channel single-ended

class D audio power output stage. The part is configured during

reset to be in either 2-channel mode or 4-channel mode.

To protect the IC as well as the connected speakers, the AD1991

provides turn-on and turn-off pop suppression, short-circuit

protection, and overtemperature shutdown. To control the IC,

a power-down/reset input and a mute pin are available.

The output stage can be operated over a power supply range

from 8 V to 20 V.

In 2-channel mode, Transistors A1, B2, C1, and D2 are turned

on by a Logic 1 on inputs INA and INC, and Transistors A2,

B1, C2, and D1 are turned on by a Logic 0 on inputs INA and

INC. In 4-channel mode, Transistors A1, B1, C1, and D1 are

turned on by a Logic 1 on the four inputs, and Transistors A2,

B2, C2, and D2 are turned on by a Logic 0 on the four inputs

(see the Functional Block Diagrams).