Auto Electronics

Class D car audio amplifiers promise 90% power efficiency

Texas Instruments has introduced the TAS5414 and TAS5424, the first members of a new family of Class D amplifiers designed especially for automotive audio applications. The TAS5414 (single-ended input) and the TAS5424 (differential input), deliver 90% power efficiency at normal radio listening levels compared with 40% to 50% efficiency for Class A/B amplifiers, according to Ryan Reynolds, automotive product marketing manager in TI’s Digital Audio group.

“Two four-channel TAS54 amplifiers can provide eight channels of audio while generating less heat than a four-channel Class A/B-based system, enabling a new class of cost-effective eight-channel audio systems that are lighter, smaller and more power efficient than existing systems,” Reynolds said. He added that the new amplifiers can be used with 2 Ohm speakers to offer twice the output power of an AB amplifier and 4 Ohm speakers, with less heat.

Reynolds said that TI had to redesign the Class D amplifiers it markets for home entertainment applications in order to meet automotive requirements. He said that an enhanced digital pulse width modulation topology, optimized gate drive technology, and patented AM interference avoidance methods were all used to optimize EMI performance and prevent interference with control systems. He added that the amplifiers need only a thin heat sink, whereas Class A/B amplifiers require larger heat sinks as well as fans.

The TAS5414 and TAS5424 come in 36-pin and 44-pin PSOP3 surface-mount packages respectively. Reynolds noted that the packages do not require mounting brackets, and thus they reduce the labor required for installation. “On-chip diagnostics simplify radio installation by testing all speaker connections, including tweeters, or short circuits created on the assembly line,” he said.

The amplifiers are sampling now, with production shipments expected in Q4. Both are TS16949 certified. Reynolds said that TI expects the devices to be AEC Q100 qualified and able to meet CISPR 25 Class 5 standards.

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