Amplifier drives bridge-tied speakers & Class-AB headphones

With an output power rating of up to 2.4W/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 the typical small internal speakers found in these types of application. A separate connection provides for single-ended driving of stereo headphones with a power output of 60mW into 32Ω loads. A DC volume control with hysteresis allows for gain adjustment from -80 to +20dB 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 2.8-5.5V supplies, consuming a quiescent current of 7mA 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.

The PAM8009 is priced at $0.48 each in the 24-pin SOP package and $0.45 each in the 20-pin QFN4040 package, in 1,000 unit quantities.