IR rolls 120-W Class D audio amp reference design

El Segundo, Calif. — The IRAUDAMP4 120-watt Class D audio power amplifier reference design from International Rectifier shows how designers can reduce printed-circuit-board (PCB) space by 50 percent for the entire mid-voltage range of mid- and high-power amplifiers for home theatre applications, professional amplifiers, musical instruments and car entertainment.

This reference design, with THD+N at 0.004% at 60 W into four ohms, demonstrates IR's state-of-the art silicon including its IRS20955 200-V digital audio driver IC and the IRF6645 DirectFET digital audio MOSFETs.

The IRAUDAMP4 reference design is a two-channel, 120-W half-bridge design offering 96% efficiency at 120-W, four ohms. The design incorporates 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 ±5-V supply for analog signal processing for the preamplifier and a +12-V supply (Vcc) referenced to -B for the Class D gate driver stage. The two-channel design is scalable for power and a number of channels, and requires no heat sink under normal operating conditions, said IR.

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, said IR.

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

Pricing: Available now, the IRAUDAMP4 reference design is currently priced at $550 each.
Datasheets: referenced IR devices and reference design(Scroll to bottom of page.)

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