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IRAUDAMP18 REV
1.0
Introduction
The IRAUDAMP18 reference design is a two-channel, 35W/ch half-bridge Class D audio power
amplifier with single power supply. This reference design demonstrates how to use the IR4312 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 two-channel design is scalable for
power and the number of channels.
Applications
Docking station audio systems
PC
audio
systems
Musical
instruments
Karaoke
amplifiers
Game
consoles
Powered
speaker
systems
Car audio amplifiers
Features
Output Power:
35W x 2 channels (4
Ω
load)
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
18-31V
Load Impedance
2-4
Ω
Resistive
load
Self-Oscillating Frequency
400kHz
No input signal, Adjustable
Gain Setting
21.4dB
1Vrms input yields rated power
Electrical Data
Typical
Notes / Conditions
IR Devices Used
IR4312 PowIRaudio integrated Class D IC
Modulator
Self-oscillating, second order sigma-delta modulation, analog input
Power Supply Range
18-31V
Single power supply;
Output Power CH1-2: (1% THD+N)
26W
1kHz
Output Power CH1-2: (10% THD+N)
35W
1kHz
Rated Load Impedance
2-4
Ω
Resistive
load
Idling Supply Current
70mA
No input signal
Total Idle Power Consumption
2.2W
No input signal
Distortion
0.018%
THD+N @ 3W, 4
Ω
Residual Noise
180
V
IHF-A weighted, AES-17 filter
Channel Efficiency
96%
Single-channel driven, 35W, Class D
stage
