International Rectifier IRAUDAMP17 Reference Design

IRAUDAMP17

100W/4Ω x 2 Channel Class D Audio Power Amplifier

Using the IR4302

By

Jun Honda, Liwei Zheng

International Rectifier suggests the following guidelines for safe operation and
handling of IRAUDAMP17 Demo board;

 Always wear safety glasses whenever operating Demo Board
 Avoid physical contact with exposed metal surfaces when operating Demo

Board

 Turn off Demo Board when placing or removing measurement probes

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CAUTION:

IRAUDAMP17 REV 1.1

TABLE OF CONTENTS ........................... PAGE

INTRODUCTION..............................................................................3

SPECIFICATIONS ...........................................................................3

CONNECTION SETUP ....................................................................4

TEST PROCEDURES......................................................................5

PERFORMANCE AND TEST GRAPHS ..........................................5

THERMAL INFORMATION..............................................................8

BILL OF MATERIALS ....................................................................10

PCB SPECIFICATIONS.................................................................11

REVISION CHANGES DESCRIPTIONS .......................................13

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IRAUDAMP17 REV 1.1

Introduction

The IRAUDAMP17 reference design is a two-channel, 100W/ch (4 Ω/52V Bus voltage) half-bridge
Class D audio power amplifier with single power supply. This reference design demonstrates how to
use the IR4302 IC with single power supply, implement protection circuits, and design an optimum
PCB layout using PowIRaudio integrated Class D IC. This reference design does not require
additional 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 two­channel 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: 100W x 2 channels (10%THD+N 4Ω load; with heatsink),
60W x 2 channels (10%THD+N 4Ω load; no 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
Over-temperature protection (OTP)

PWM Modulator: Self-oscillating half-bridge topology

Specifications

General Test Conditions (unless otherwise noted) Notes / Conditions

Supply Voltages

Load Impedance 2-4Ω Resistive load
Self-Oscillating Frequency 400kHz No input signal, Adjustable
Gain Setting 24.8dB 1Vrms input yields rated power

Electrical Data Typical Notes / Conditions

IR Devices Used IR4302 PowIRaudio integrated Class D IC
Modulator Self-oscillating, second order sigma-delta modulation, analog input

Power Supply Range

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

Output Power CH1-2: (10% THD+N)

Rated Load Impedance 2-4Ω Resistive load
Idling Supply Current 65mA No input signal
Total Idle Power Consumption 3.4W No input signal
Distortion 0.008% THD+N @ 30W, 4Ω

40V~52V With heatsink

30V~42V *Without heatsink

40V~52V

30V~42V *Without heatsink

75W 1kHz, 4Ω load, with heatsink

50W 1kHz, 4Ω load, without heatsink

100W 1kHz, 4Ω load, with heatsink

60W 1kHz, 4Ω load, without heatsink

Single power supply;

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IRAUDAMP17 REV 1.1

Residual Noise

220V

Channel Efficiency 96%

*Need to change components as below to achieve 30V~42V power supply voltage range without heatsink

With Heatsink Without Heatsink

Power Supply Voltage Range 40~52V 30~42V

R7~R10 390Ω 240Ω

Z5 36V 27V

Connection Setup

40-52V*, 3A DC supply

P1

P2

CH1

Output

P3

CH2

Output

IHF-A weighted, AES-17 filter

Single-channel driven,100W Class D
stage

* Without heatsink Power supply
voltage range is 30~42V

250W, Non-inductive Resistors

4 Ohm 4 Ohm

CLIP
Indicator

Audio Signal Generator

Connector Description

Audio IN CN1 Analog input for CH1 and CH2
POWER P3 Single supply
CH1 OUT P1 Output for CH1
CH2 OUT P2 Output for CH2

Audio

Input

Power
Indicator

IR4302

CN1

FAULT
Indicator

SW1

Fig 1 Typical Test Setup

SW1:PWM Shutdown/MUTE

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IRAUDAMP17 REV 1.1

Test Procedures

Test Setup:

1. Connect 4, 250W load to both output connectors, P1 and P2 and audio analyzer (Ap).

2. Connect Audio Signal Generator to CN1 for CH1 and CH2 respectively (Ap).

3. Connect a single power supply to P3 pre-adjusted to 40-52V as shown on Figure above

4. Turn on the power supply.

5. Turn on SW1 (right side).

6. Blue LED (Normal) stays turning on after RED LED extinguished.

7. With an Oscilloscope, monitor switching waveform at VS of CH1 and CH2.

8. Quiescent current for the power supply should be 70mA 10mA at 52V.

Functionality Audio Tests:

9. Sweep the audio signal voltage from 15 mV

10. Monitor the output signals at P1/P2 with an oscilloscope. The waveform must be a non
distorted sinusoidal signal with input sinusoidal signal below 1Vrms.

RMS

to 1.5 V

RMS

.

Performance and Test Graphs

Power vs THD+N

Test Conditions:

Load Impedance = 4 ohms

VBus = 52V(with heatsink)
Input Signal=1 kHz

10

5

2

1

0.5

0.2

0.1

%

0.05

0.02

0.01

0.005

0.002

0.001
20m 20050m 100m 200m 500m 1 2 5 10 20 50 100

W

ColorSweep Trace Line Sty le Thick Data Axis Comment

1 1 Blue Solid 2 Anlr.THD+N Ratio Left CH1 4ohms 52V
1 3 Magenta Solid 2 Anlr.THD+N Ratio Left CH2 4ohms 52V

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Fig 2

IRAUDAMP17 REV 1.1