Diodes 3W Stereo Class D audio amplifier Drive bridge stereo speakers and AB headphones

     Diodes Incorporated introduced a 3W stereo Class D audio amplifier and a Class AB headphone driver, the PAM8009, aimed at manufacturers of liquid crystal displays, all-in-one personal computers and video projectors. The amplifier features power limiting technology to protect the speaker and advanced DC volume control for precise gain adjustment of 64 levels. It minimizes the number of external components and thus provides a highly integrated solution in a compact 20-pin QFN or 24-pin SOP package.

     The PAM8009 provides an output power rating of up to 2.4W per channel at 1% total harmonic distortion (THD+N) to drive 4Ω bridge speaker loads; At 10% total harmonic distortion, the output power is up to 3W. The device enables a low cost and high power drive for typically small internal speakers for such applications. A separate audio interface drives a 60mW power output stereo headset in single-ended mode for a 32Ω load, and DC volume control with hysteresis enables precise 64-point gain adjustment from -80dB to +20dB. Automatic gain control and undervoltage protection protect the speaker from output clipping and shut down the amplifier before the input generates power drop noise.

     The PAM8009 has a supply voltage range of 2.8V to 5.5V and consumes 7mA of static current on a 5V supply. The device integrates thermal protection and overcurrent protection into self-recovery and uses a power-enhanced package to reduce power consumption. The mute pin speeds up the shutdown of the speaker and headphone output, which also helps to save power. To further reduce power consumption, the product's off mode turns off the amplifier's bias current.