Silicon Laboratories Inc. has introduced a family of isolated gate drivers designed for high-power Class D audio systems with output power ranging from 30 to 1000 W. The Si824x Class D audio driver family provides exceptional high-fidelity performance, robust noise tolerance, and precise dead-time control for a wide range of digital audio applications.

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Class D amplifiers are rapidly replacing Class AB amplifiers in high-power audio applications. Digital signals in high-power Class D designs require careful control of the “dead time” between pull-up and pull-down stages to optimize performance. While competing audio drivers provide limited capabilities to tweak dead time, the Si824x ICs support precise dead-time control based on the value of an external resistor. The developer can adjust the dead time simply by changing the resistor value, making it easy to meet varying audio design requirements.

Based on Silicon Labs’ proven digital isolation technology, the Si824x audio drivers provide high-voltage isolation of up to 2.5 kV between input and output stages, enabling the input stage to be driven by low-voltage Class D control signals while the output drives the high-voltage, high-current output-stage transistors. Isolating the input stage from the output stage prevents noise and transients from corrupting sensitive signals. The high-side and low-side outputs are isolated from each other and can be driven up to 1500 V, enabling the Si824x ICs to support high-power audio requirements.

By isolating input and output stages, the Si824x architecture offers the advantage of built-in level shifting. The gate driver’s isolated architecture allows the audio system to seamlessly interface the high-voltage power stage with the low-voltage DSP/modulator stage without requiring any extra bill-of-materials (BOM) components. In addition, the power voltages can be arbitrarily chosen, eliminating the need for costly dc-blocking capacitors often required by competitive solutions.

Designed to operate in noisy environments, the Si824x drivers are inherently immune to power-supply transients that can cause damage inducing “latch-up.” This built-in latch-up immunity enables superior manufacturing and operational reliability and lower BOM costs. Some audio amplifier designs based on competing audio drivers contain up to 20 discrete components to protect the driver ICs from latch-up.

Samples and pre-production quantities of the Si824x Class D audio drivers are available now in a 16-pin narrow body small-outline IC (SOIC) package. Pricing in 10,000-unit quantities begins at $1.82 each. To ease application development, Silicon Labs offers the full-featured Si824xClassD-KIT evaluation board priced at $250 (USD). For additional Si824x product information, visit www.silabs.com/pr/audio-driver.

Silicon Labs