CLASS-D Audio Amp Simplifies Flat-Panel TV Design

The NCS8353 is a 20-W per channel (continuous), Class-D stereo audio amplifier for flat-panel TVs. Thanks to efficiency greater than 87%, it doesn’t need a heat sink. It operates from the TV’s 24-V backlight rail and each output is designed to operate into an 8-Ω bridge-tied load. The speakers themselves filter out the class-D switching frequency. Under shutdown conditions, quiescent draw is 100 µA (typical). Special features include short-circuit protection, four selectable gain ranges: 20, 26, 32, and 36 dB, and an integrated digital power limiter that can be set to 10, 12, 15, or 20 W. If Tj rises above 150 °C, the internal gain of the device is slowly reduced. The output stage shuts down completely if Tj rises above 160 °C, and is re-enabled once Tj cools to below 130 °C. Packaged in a 32-pin, 5 x 5-mm QFN, the NCS8353 is priced at $0.78 per unit in 10,000-unit quantities. ON SEMICONDUCTOR, Phoenix, AZ.(602)-244-6600.