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Si824xClassD-KIT
CLASS D AUDIO AMPLIFIER REFERENCE DESIGN USER’S 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
Si8410 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. Th
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Si824xClassD-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
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Si824xClassD-KIT 3.3. Powering up the Class D Amplifier and Playing Music After the audio source, audio Y-cable, supplies, and speakers have been properly connected as shown in Figure 3. 1. Turn on the ±12 V supplies. 2. Then, turn on the ±50 V supplies. Notice that LED1 should turn on for about 1 sec and then turn off. This on and off sequence clears any overcurrent protection faults and indicates to the user that the amplifier is ready to amplify the audio input signal. If the LED does not
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Si824xClassD-KIT 4. Additional Features and Architectural Considerations 4.1. Gate Drive Structure Figure 5 illustrates the ease with which the Si8241 can drive a two-state, half-bridge class D amplifier. The boot supply tied to D1 must be 12 V higher than the –50 V reference (–38 V) so that the MOSFETs each have a 12 V drive signal. The closed loop gain of the Silicon Labs Class D reference design is implemented such that approximately 1 Vpp input will yield full output power into an 8 load
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Si824xClassD-KIT 50V 5V R2 Si8410 D1 RSENSE C1 Digital Isolator VDD1 VDD2 VDD1 + B1 SHUTDOWN A1 GND2 - R4 R1 GND1 GND2 R3 To High Side R5 MOSFET Figure 6. Over Current Protection Circuit 4.5. Undervoltage Protection The undervoltage protection comparator monitors the positive bus voltage and releases the undervoltage lockout when the voltage is above 37 V. The amplifier starts up after a one-second delay. Note that the red LED remains lit when the amplifier is in shutdown mode and turns off w
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Si824xClassD-KIT 5. Si8241-Based Class D Amplifier Connection Description The Si8241-based Class D Amplifier has two Si8241 ISOdrivers and two Si8410 digital isolators installed. Refer to Figure 7 for the locations of the various I/O connectors and major components. Relevant user connection points are detailed below. J1 +50 V Positive Input Power: Input power connection +50 V, 3 A. J2 PGND Power Ground Return, 0 V. J3 –50 V Negative Input Power: Input power connection –50 V, 3 A. J4 SPK
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Si824xClassD-KIT 6. Schematics Rev. 0.2 7 Figure 8. Si824x Class D Audio Amplifier Reference Design Schematic (1 of 2)
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Si824xClassD-KIT 8 Rev. 0.2 Figure 9. Si824x Class D Audio Amplifier Reference Design Schematic (2 of 2)
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Si824xClassD-KIT 7. Bill of Materials Table 1. Si824x Class D Audio Amplifier Reference Design Bill of Materials Qty Ref Description Mfr. Part Number Mfr Digikey Part Number 1µF, 25 V, X5R, 2C1, C2 0805 Ceramic 08053D105KAT2A AVX 478-1409-6-ND Capacitor 1 µF, 16 V, 3216 2C3, C4 T491A105M016AT Kemet 399-3681-6-ND Tantalum Capacitor C24–C27, 0.1 µF, 50 V, X7R, GRM188R71H104 14 C29, C30, 0603 Ceramic Murata 490-1519-6-ND KA93D C37–C44 Capacitor 10 µF, 10 V, 3216 1C6 T491A106M010AT Kemet 399-
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Si824xClassD-KIT Table 1. Si824x Class D Audio Amplifier Reference Design Bill of Materials (Continued) Qty Ref Description Mfr. Part Number Mfr Digikey Part Number 82 µF, 63 V, KZE EKZE630ESS820M 4 C67–C70 Series Electrolytic Chemi-Con 565-1721-ND JC5S Cap 0.1 µF, 100 V, X7R, 4 C71–C74 1206 Ceramic 12061C104MAT2A AVX 478-3786-6-ND Capacitor 0.01 µF, 100 V, 4 C75–C78 COG, 1206 Ceramic 12061C103JAT2A AVX 478-3783-6-ND Capacitor 0.47 µF, 250 V Film 2C79, C80 ECQ-E2474KB Panasonic ECG P10975-ND
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Si824xClassD-KIT Table 1. Si824x Class D Audio Amplifier Reference Design Bill of Materials (Continued) Qty Ref Description Mfr. Part Number Mfr Digikey Part Number IC Comp Grnd-sens- 2 IC19, IC20 LT1671CS8#PBF Linear Tech LT1671CS8#PBF-ND ing LowPwr 8SOIC Isodriver Narrow 2 IC21, IC22 Si8241BB-B-IS1 Silabs Body Tyco 7 J1–J7 1/4 inch-Faston 62409-1 A24742-ND Electronics 1 J8 3 Pin Conn Header 22-23-2031 Molex Inc. WM4201-ND Conn RCA Jack 2 J9, J10 RCJ-014 CUI Inc. CP-1403-ND Metal R/A YEL PCB
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Si824xClassD-KIT Table 1. Si824x Class D Audio Amplifier Reference Design Bill of Materials (Continued) Qty Ref Description Mfr. Part Number Mfr Digikey Part Number 12.1 k, 2010 1% 2R16, R17 ERJ-12SF1212U Panasonic ECG P12.1KACCT-ND SMT Resistor R18, R21, 20 k , 0603 1% 3 ERJ-3EKF2002V Panasonic ECG P20.0KHCT-ND R60 SMT Resistor 4.99 k , 0603 1% 2R29, R30 ERJ-3EKF4991V Panasonic ECG P4.99KHCT-ND SMT Resistor R23, R24, 100 k , 0603 1% 4 ERJ-3EKF1003V Panasonic ECG P100KHCT-ND R39, R40
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Si824xClassD-KIT Table 1. Si824x Class D Audio Amplifier Reference Design Bill of Materials (Continued) Qty Ref Description Mfr. Part Number Mfr Digikey Part Number Insulator Mica 4 Insulator .860X.520" .141" 4672 Keystone 4672K-ND TO-220 Hdwr Mtg Screw TO- 4Screw 220CASE 4/40 THR 4690 Keystone 4690K-ND 1PC Hdwr Mtg Screw 1/ 4Screw 4" 4/40 , PCB L- 9900 Keystone 9900K-ND Bracket Mount Lock Hdwr Mtg Lock- 4 4693 Keystone 4693K-ND Washer washer Plastic 2PC Hdwr Mtg Nut 4/40 4Nut 4694 Keystone 46
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Si824xClassD-KIT 8. Ordering Guide Ordering Part Number Type Audio Class D Amplifier reference design kit using Si824xClassD-KIT Si8241BB-B-IS1. 14 Rev. 0.2
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Si824xClassD-KIT DOCUMENT CHANGE LIST Revision 0.1 to Revision 0.2 Updated Table 1, “Si824x Class D Audio Amplifier Reference Design Bill of Materials,” on page 9. Rev. 0.2 15
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Si824xClassD-KIT CONTACT INFORMATION Silicon Laboratories Inc. 400 West Cesar Chavez Austin, TX 78701 Tel: 1+(512) 416-8500 Fax: 1+(512) 416-9669 Toll Free: 1+(877) 444-3032 Please visit the Silicon Labs Technical Support web page: https://www.silabs.com/support/pages/contacttechnicalsupport.aspx and register to submit a technical support request. The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice. Silic
