IRAUDAMP4A 120 W x 2 Channel Class D Audio Power Amplifier Using IRS20957 and IRF6645 By Johan Strydom, Jun Honda, and Jorge Cerezo Table of Contents Page Introduction .......................................................................................... 1 Specifications....................................................................................... 2 Functional Description.......................................................................... 4 Startup and Shutdown..........................................................................12 Protection.............................................................................................16 Typical Performance ............................................................................21 Design Documents ..............................................................................27 CAUTION: International Rectifier suggests the following guidelines for safe operation and handling of IRAUDAMP4A Demo Board Always wear safety glasses whenever operating Demo Board Avoid personal contact with exposed metal surfaces when operating Demo Board Turn off Demo Board when placing or removing measurement probes www.irf.com IRAUDAMP4A Introduction The IRAUDAMP4A reference design is an example of a two-channel 120 W half-bridge Class D audio power amplifier. The reference design will demonstrate how to use the IRS20957, implement protection circuits, and design an optimum PCB layout using the IRF6645 DirectFET MOSFETs. The resulting design requires no heatsink for normal operation (one-eighth of continuous rated power). The reference design contains 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 Sub-woofers Features Output Power: 120 W x two channels, Total Harmonic Distortion (THD) = 1%, 1 kHz Residual Noise: 52 V, IHF-A weighted, AES-17 filter Distortion: 0.004% THD+N 60 W, 4 Efficiency: 96% 120 W, 4 , single-channel driven, Class D stage Multiple Protection Features: Over-current protection (OCP), Over-voltage protection (OVP), Under-voltage protection (UVP), DC-protection (DCP), Over-temperature protection (OTP) PWM Modulator: Self-oscillating half-bridge topology with optional clock synchronization www.irf.com 1 IRAUDAMP4A