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Introduction

The IRAUDAMP21 reference design is a two-channel, 90W/ch (2Ω/±18V; no heatsink)/ 135W/ch

(2Ω/±22V; *with heatsink) half-bridge Class D audio power amplifier. This reference design

demonstrates how to use the IR4321 IC, implement protection circuits, and design an optimum PCB

layout using PowIRaudio integrated Class D IC. This reference design does not require heatsink or

fan cooling for normal operation (one-eighth of continuous rated power).The reference design

provides all the required housekeeping power supplies for ease of use. The two-channel design is

scalable for power and the number of channels.

Applications



AV receivers



Home theater systems



Mini component stereos



Powered speakers



Sub-woofers



Musical Instrument amplifiers



Car audio amplifiers

Features

Output Power:

90W x 2 channels (10%THD+N 2Ω load; no heatsink),

135W x 2 channels (10%THD+N 2Ω load; *with heatsink),

Multiple Protection Features:

Over-current protection (OCP), high side and low side

Over-voltage protection (OVP),

Under-voltage protection (UVP), high side and low side

DC-protection (DCP),

Over-temperature protection (OTP)

PWM Modulator:

Self-oscillating half-bridge topology with optional clock

synchronization

Specifications

General Test Conditions (unless otherwise noted)

Notes / Conditions

±12V~±18V

Bipolar power supply; without heatsink

Supply Voltages

±12V~±22V

Bipolar power supply; *with heatsink

Load Impedance

4-2Ω

Resistive load

Self-Oscillating Frequency

400kHz

No input signal, Adjustable

Gain Setting

26dB

1Vrms input yields rated power

Electrical Data

Typical

Notes / Conditions

IR Devices Used

IR4321 PowIRaudio integrated Class D IC

Modulator

Self-oscillating, second order sigma-delta modulation, analog input

70W

1kHz, 4Ω load, without heatsink

70W

1kHz, 4Ω load, *with heatsink

90W

1kHz, 3Ω load, without heatsink

90W

1kHz, 3Ω load, *with heatsink

70W

1kHz, 2Ω load, without heatsink

Output Power CH1-2: (1% THD+N)

100W

1kHz, 2Ω load, *with heatsink