3W stereo class-D audio amp drives stereo speakers or class-AB headphones

March 02, 2015 // By Graham Prophet
PAM8009 from Diodes Incorporated is a 3W stereo class-D audio amplifier and class-AB headphone driver. Featuring power limit technology for speaker protection and a DC volume control for precise 64-step gain adjustment, this amplifier minimises external components to achieve a highly integrated solution in 20-pin QFN or 24-pin SOP packages.

With an output power rating of up to 2.4 W/channel into 4Ω bridge-tied speakers at a THD+N of 1% (up to 3W at 10% THD+N), the PAM8009 provides a high-power, low-cost capability for driving typical small internal speakers. A separate connection provides for single-ended driving of stereo headphones with a power output of 60 mW into 32Ω loads. A DC volume control with hysteresis allows for gain adjustment from -80 dB to +20 dB in 64 steps. Automatic gain control and under-voltage protection functions prevent speaker damage due to output clipping and will shut down the amplifier before an input device generates a ‘pop’.

The PAM8009 operates from 2.8V to 5.5V supplies, consuming a quiescent current of 7 mA at 5V. Thermal and over-current protection is incorporated with auto-recovery and the device is supplied in power-enhanced packages to aid power dissipation. A mute pin allows the speaker/headphone outputs to be quickly disabled, also helping to save power. To further reduce power consumption a shutdown mode turns off the amplifier’s bias circuit.

PAM8009 is priced at $0.48 in the SOP-24 package and $0.45 USD in the QFN4040-20 package (1000).

Diodes Inc.; www.diodes.com