International Rectifier Introduces New High Performance Two-Channel 120W Class D Audio Amp Reference Design

EL SEGUNDO, Calif. - International Rectifier, IR® (NYSE: IRF), a world leader in power management technology, today introduced the IRAUDAMP4 Class D audio power amplifier reference design. Compared to typical circuit designs, the new reference design illustrates how designers can reduce PCB board space by 50 percent for Class D audio amplifiers for the entire mid-voltage range of mid- and high-power amplifiers for home theatre applications, professional amplifiers, musical instruments and car entertainment.

“With THD+N at 0.004% at 60W into four ohms, this reference design demonstrates IR’s state-of-the art silicon enabling the best in audio performance from Class D topology,” said Stephane Ernoux, product marketing manager at International Rectifier.

Showcasing IR’s IRS20955 200V digital audio driver IC and the IRF6645 DirectFET® digital audio MOSFETs, the IRAUDAMP4 reference design is a two-channel, 120W half-bridge design offering 96% efficiency at 120W, four ohms. The design incorporates critical protection features such as over-current protection, over-voltage protection, under-voltage protection, DC-protection, and over-temperature protection, in addition to housekeeping functions such as a +/- 5V supply for analog signal processing for the preamplifier and a +12V supply (Vcc) referenced to -B for the Class D gate driver stage. The two-channel design is scalable for power and number of channels, and requires no heatsink under normal operating conditions.

The IRS20955(S)(TR)PbF audio driver IC, on which the reference design is based, features a floating PWM input designed specifically for Class D audio amplifier applications. Bi-directional current sensing detects over-current conditions during positive and negative load currents without any external shunt resistors. A built-in protection control block provides a secure protection sequence against over-current conditions and a programmable reset timer. The internal deadtime generation block enables accurate gate switching and optimum deadtime setting for better audio performance, such as lower THD and lower audio noise floor.

The featured companion IRF6645 power MOSFETs are part of IR’s DirectFET family. The innovative DirectFET packaging technology enhances performance in Class D audio amplifier circuits by reducing lead inductance to improve switching performance and reduce EMI noise. The higher thermal efficiency enables 120W operation into four-ohms, eliminating the need for a heatsink to shrink circuit size, provide greater layout flexibility and reduce overall amplifier system cost.

Part Number Audio Driver IC Digital Audio MOSFET Supply Voltage Load Impedance Frequency Gain Setting
IRAUDAMP4 IRS20955(S) IRF6645 +/-35V 4-Ohms 400kHz 26.8dB

Availability and Pricing

The IRAUDAMP4 reference design is available immediately. US pricing is $550 each and is subject to change.