Meeting Energy Star™ Guidelines Now Possible with Silicon Labs Si824x Class D Audio Drivers
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High-power audio systems are adopting digital audio technology and evolving toward lower-power, “green” products that meet Energy Star™ guidelines. Class D audio systems have begun penetrating the high-end markets, where low noise, extremely good THD performance and very high output power are required in consumer and industrial applications. The Si824x audio driver family consists of single-chip, isolated Class D gate drivers that power audio systems delivering from 30 to 1000 W of audio power.
The Si824x audio drivers are a perfect solution if you are building high-power Class D audio systems that use discrete driver stages. Typical applications include home entertainment systems, high-fidelity audio receivers, powered speakers, guitar amps, public address (PA) systems, alarms and sirens, and car stereos.
Compared to non-isolated gate drive solutions, the Si824x audio drivers incorporate input-to-output isolation, enabling level-translation of signals without additional external circuits. Si824x audio drivers feature adjustable dead-time control for achieving optimal THD, overlap protection that safeguards against shoot-through current damage, robust immunity to latch-up, high-voltage transients, lower BOM costs and smaller PCB footprints.
Innovative Features
- Isolated Driver Architecture: Provides high-voltage isolation – up to 2.5 kV – between the input and output stages. This enables the input stage to be driven by low-voltage Class D control signals from a SoC IC, while the output drives the high-voltage, high-current output-stage transistors.
- Built-in Level-Shifting: The output stage can be driven to a voltage range independent of the input voltage levels. The Si824x inherently performs the desired level shifting to the output voltage reference.
- Precision Dead-Time Control: Provides precise control of the dead-time based on the value of an external resistor. The dead-time can be adjusted by simply changing the resistor value, enabling modification for meeting different design requirements.
- Robust Noise Tolerance: CMOS isolators posses the ability to operate in noisy environments and are highly immune to noise transients that can cause latch-up and destructive power consumption. The Si824x provides significant immunity to noise and voltage transients:
- Up to 2.5 kVrms input-to-output isolationo
- Up to 100 V/ns latch-up immunity
- Low emissions enable FCC Class B EMI, EMC compliance
- High Speed Operation: Signal integrity is maintained even while operating at high data rates. High speed operation is maintained over the entire industrial temperature range (-40 to 125 °C). Minimizing propagation delay allows higher modulation frequencies in Class D systems.
Si824x Class D Reference Design
This reference design leverages the performance advantages of the Si8241BB-B-IS1 for a 2-channel Class D audio amplifier, delivering 120 W per channel into 8 Ω, while enabling < 0.02% THD at 60 W and SNR > 95 dB.