Audio amplifier handles start/stop transients in cars

October 08, 2013 // By Graham Prophet
STMicroelectronics' TDA7802 is an automotive start/stop-compatible audio power amplifier that combines the performance and cost benefits of a digital input with the simplicity and enhanced efficiency of analogue class SB-I amplification.

The TDA7802 extends ST's family of “green power” products designed to support advanced technologies for cleaner cars, such as start/stop (micro-hybrid), which reduces emissions by cutting the engine instead of idling. The TDA7802 operates seamlessly even when its supply voltage drops as the engine restarts. Its digital input connects directly to a digital sound processor, saving digital/analogue converter and low-pass filter components. This approach reduces application size and cost, while ensuring clearer sound and improving coexistence with other equipment such as mobile phones.

The class SB-I (SB-Improved) analogue amplifier can achieve 50% lower heat dissipation than a class AB analogue amplifier, allowing smaller heatsinks or extra functionality in the head unit within the same thermal budget. The thermal performance makes the TDA7802 a valuable alternative when a class D solution cannot be used.

The TDA7802 delivers 4x50W into 4 Ω speakers and will drive loads as low as 1 Ω. It has outstanding noise performance, achieving SNR of 115 dB, and over 110 dB dynamic range. Built-in diagnostics protect against short-circuit failures or speaker disconnection. It comes in PowerSO36 or Flexiwatt27 through-hole/surface-mount packages, priced from $7.00 (1000).