The TPA321D is a bridge-tied load (BTL) Audio Power Amplifier developed especially for low-voltage applications where internal speakers are required. Operating with a 3.3V supply, the TPA321 can deliver 250mW of continuous power into a BTL 8R load at less than 1% THD+N throughout voice band frequencies. Although this device is characterized out to 20kHz, its operation was optimized for narrower band applications such as cellular communications. The BTL configuration eliminates the need for external coupling capacitors on the output in most applications, which is particularly important for small battery-powered equipment. This device features a shutdown mode for power-sensitive applications with a quiescent current of 0.15μA during shutdown.