Si824xClassD-KIT CLASS D AUDIO AMPLIFIER REFERENCE DESIGN USERS GUIDE 1. Kit Contents The Si824x Class D Audio Amplifier Reference Design Kit contains the following items: Audio Class D Amplifier reference design board featuring: Si8241 ISOdriver Si8610 Digital Isolator 2. Introduction This User s Guide discusses the Silicon Labs Audio Class D amplifier reference design, a stereo, two-state, half- bridge Class D amplifier leveraging the performance advantages of the Si8241 ISOdriver. This two-channel Class D Audio Amplifier delivers 120 W per channel into 8 , while enabling < 0.02% THD at 60 W and > 95 dB SNR. 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 started 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 powering audio systems delivering from 30 W up to 1000 W of audio power. Occasionally, a new IC is introduced that challenges the current technological hegemony. With features that make these products the perfect drivers for Class D amplification, the Silicon Labs Si8241/44 Audio Gate Drivers represent a new standard for the Class D amplifier industry. Based on Silicon Labs proprietary isolation technology, the Si824x audio drivers incorporate input-to-output isolation that enables level-translation of signals without additional external circuits. The 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 and high-voltage transients, and lower BOM costs and PCB footprints compared to non-isolated gate drive solutions. A typical audio driver application using the Si824x is shown in Figure 1. For more information on the Si824x audio driver, refer to the Si824x data sheet at www.silabs.com/products/audio. Figure 1. Si824x-Based Class D Audio Driver Block Diagram Rev. 0.3 7/16 Copyright 2016 by Silicon Laboratories Si824xClassD-KITSi824xClassD-KIT 3. Hardware Overview and Demo 3.1. Reference Design Board Architecture The Silicon Labs Class D reference design architecture uses a phase-shift, self-oscillating modulation approach that is capable of achieving far greater signal-to-noise ratio than clock driven amplifiers (see Figure 2). This self- oscillating implementation eliminates the circuitry necessary to generate the triangle waveform. To keep the circuit as simple as possible, a two-state, half-bridge is implemented and exemplifies the benefits of using the Si8241 Audio Gate Driver. Figure 2. Block Diagram of Si8241-Based Class D Amplifier 3.2. Setting up the Class D Amplifier Figure 3 illustrates connections necessary to power the Class D amplifier. The user will need the following items: MP3 player (or equivalent line out audio source) Audio Y-Cable (stereo male to Dual RCA Male) 50 V supply capable of sourcing 3 Amps 12 V supply capable of sourcing 500 mA Two speakers (up to 150 W) Silicon Labs Class D reference design board Warning: 1. To protect the amplifier and speakers, before turning on the main power (the 50 V supplies) to the amplifier, ensure that the audio source from the MP3 player has its volume set to the lowest possible level. 2. The L-bracket can heat up to 80 C and should be handled with care. 2 Rev. 0.3