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IRAUDAMP18
35W/4Ω x 2 Channel Class D Audio Power Amplifier
Using the IR4312
By
Jun Honda, Liwei Zheng
International Rectifier suggests the following guidelines for safe operation and
handling of IRAUDAMP18 Demo board;
Always wear safety glasses whenever operating Demo Board
Avoid physical contact with exposed metal surfaces when operating Demo
Board
Turn off Demo Board when placing or removing measurement probes
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CAUTION:
IRAUDAMP18 REV 1.0
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TABLE OF CONTENTS ........................... PAGE
INTRODUCTION..............................................................................3
SPECIFICATIONS ...........................................................................3
CONNECTION SETUP ....................................................................4
TEST PROCEDURES......................................................................5
PERFORMANCE AND TEST GRAPHS ..........................................5
THERMAL INFORMATION..............................................................8
SCHEMATIC ....................................................................................9
IRAUDAMP18 BILL OF MATERIALS ............................................10
IRAUDAMP18 PCB SPECIFICATIONS.........................................11
REVISION CHANGES DESCRIPTIONS .......................................13
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IRAUDAMP18 REV 1.0
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Introduction
The IRAUDAMP18 reference design is a two-channel, 35W/ch half-bridge Class D audio power
amplifier with single power supply. This reference design demonstrates how to use the IR4312 IC
with single power supply, implement protection circuits, and design an optimum PCB layout using
PowIRaudio integrated Class D IC. This reference design does not require additional heatsink or fan
cooling for normal operation (one-eighth of continuous rated power).The reference design provides all
the required housekeeping power supplies for ease of use. The two-channel design is scalable for
power and the number of channels.
Applications
Docking station audio systems
PC audio systems
Musical instruments
Karaoke amplifiers
Game consoles
Powered speaker systems
Car audio amplifiers
Features
Output Power: 35W x 2 channels (4Ω load)
Multiple Protection Features: Over-current protection (OCP), high side and low side
Over-voltage protection (OVP),
Under-voltage protection (UVP), high side and low side
Over-temperature protection (OTP)
PWM Modulator: Self-oscillating half-bridge topology
Specifications
General Test Conditions (unless otherwise noted) Notes / Conditions
Supply Voltages 18-31V
Load Impedance 2-4Ω Resistive load
Self-Oscillating Frequency 400kHz No input signal, Adjustable
Gain Setting 21.4dB 1Vrms input yields rated power
Electrical Data Typical Notes / Conditions
IR Devices Used IR4312 PowIRaudio integrated Class D IC
Modulator Self-oscillating, second order sigma-delta modulation, analog input
Power Supply Range 18-31V
Output Power CH1-2: (1% THD+N) 26W 1kHz
Output Power CH1-2: (10% THD+N) 35W 1kHz
Rated Load Impedance 2-4Ω Resistive load
Idling Supply Current 70mA No input signal
Total Idle Power Consumption 2.2W No input signal
Distortion 0.018% THD+N @ 3W, 4Ω
Residual Noise
Channel Efficiency 96%
180V
Single power supply;
IHF-A weighted, AES-17 filter
Single-channel driven, 35W, Class D
stage
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IRAUDAMP18 REV 1.0
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Connection Setup
P2
P1
18-31 3A DC supply
P3
100W, Non-inductive Resistors
4 Ohm 4 Ohm
CH1
Output
CLIP
Indicator
Audio
Input
Audio Signal Generator
Connector Description
Audio IN CN1 Analog input for CH1 and CH2
POWER P3 Single supply
CH1 OUT P1 Output for CH1
CH2 OUT P2 Output for CH2
CH2
Output
Power
Indicator
IR4312
CN1
FAULT
Indicator
SW1
Fig 1 Typical Test Setup
SW1:PWM Shutdown/MUTE
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IRAUDAMP18 REV 1.0
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Test Procedures
Test Setup:
1. Connect 4, 100W load to both output connectors, P1 and P2 and audio analyzer (Ap).
2. Connect Audio Signal Generator to CN1 for CH1 and CH2 respectively (Ap).
3. Connect a single power supply to P3 pre-adjusted to 18-31V as shown on Figure above
4. Turn on the power supply.
5. Turn on SW1(right side).
6. Blue LED (Normal) stays turning on after RED LED extinguished.
7. With an Oscilloscope, monitor switching waveform at VS of CH1 and CH2.
8. Quiescent current for the power supply should be 70mA 10mA at 31V.
Functionality Audio Tests:
9. Sweep the audio signal voltage from 15 mV
to 1.5 V
RMS
10. Monitor the output signals at P1/P2 with an oscilloscope. The waveform must be a non
distorted sinusoidal signal with input sinusoidal signal below 1Vrms.
RMS
.
Performance and Test Graphs
Power vs THD+N
Test Conditions:
Load Impedance = 4 ohms
VBus = 31V
Input Signal=1 kHz
10
5
THD+N vs Power
2
1
0.5
0.2
0.1
%
0.05
0.02
0.01
0.005
0.002
0.001
20m 4050m 100m 200m 500m 1 2 5 10 20
W
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Red Solid 2 Anlr.THD+N Ratio Left Ch1 4ohms 31V
1 3 B lue Solid 2 Anlr. THD+N Ratio Left Ch2 4ohms 31V
Fig 2
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IRAUDAMP18 REV 1.0
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Frequency Response
Test Conditions:
Load Impedance = 4 ohms
VBus = 31V
Set Output = 1V
+4
+2
+0
d
B
A
-2
r
-4
-6
-8
-10
20 200k50 100 200 500 1k 2k 5k 10k 20k 50k 100k
Hz
ColorSweep Trac e Line Style Thick Data Ax is Comment
1 1 Red Solid 2 Anlr.Level A Left Ch1 4ohm SP 25V
1 2 Blue Solid 2 Anlr.Level B Left Ch2 4ohm SP 25V
Noise Floor
Test Conditions:
Load Impedance = 4 ohms
No Input Signal
VBus = 31V
+20
d
B
V
-100
-120
-140
+0
-20
-40
-60
-80
10 20k20 50 100 200 500 1k 2k 5k 10k
Fig 3
Hz
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Red Solid 2 Fft.Ch.1 A mpl Left Ch1
1 2 Blue Solid 2 Fft.Ch.2 Ampl Left Ch2
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Fig 4
IRAUDAMP18 REV 1.0
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Noise Floor with 1Vrms Output
Test Conditions:
Load Impedance = 4 ohms
VBus = 31V
Output = 1Vrms @ 1 KHz
+0
-20
-40
d
B
-60
V
-80
-100
10 20k20 50 100 200 500 1k 2k 5k 10k
Hz
Efficiency
ColorSweep Trace Line St yle Thick Data Ax is Comment
1 1 Red Solid 2 Fft.Ch.1 Ampl Left Ch1 4ohm
1 2 Blue Solid 2 Fft.Ch.2 Ampl Left Ch2 4ohm
Fig 5
100.0%
90.0%
80.0%
70.0%
60.0%
50.0%
40.0%
Efficiency
30.0%
20.0%
10.0%
0.0%
0 5 10 15 20 25 30 35 40
Power (W)
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Fig 6
IRAUDAMP18 REV 1.0
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Thermal Information:
1/8 Po Thermal Test
Conditions:
Tamb=25°C natural convection cooling
Both Channel Driven 1/8Po continuous 30mins
Temperature measured by infrared camera
Fig 7 IRAUDAMP18 (Vbus=31V)
IR4312’s temperature saturated around 75°C within 30minutes
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IRAUDAMP18 REV 1.0
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Schematic
Z5
16V
R56
10k
+B
R55
+B
R52
+B
2
354
S1
1
OFF
UVP
47k
R53
10k
Z4
10k
33V
OVP
R51
47k
6
SW SPDT
ON
SD
+B
CT_PGN D
R57
47k
MMBT5551
Q3
C35
0.1uF
MMBT5551
Q2
GND
GND
1
2
LCH
P1
CT_PGND
+B
C38
C36
+
1
2
P3
+B
GND
2200uF, 25V
2200uF, 25V
C39
C37
0.1uF,100V
0.1uF,100V
R48 10k, 1/2WR4910k, 1/2W
GND
GND
R50
10R0
INPUT GND
R47
-
1
2
RCH
P2
CT_PGND
NM
CT_SGND CT_PGND
CT_PGND
+B
R45 2.2k
D6
D7
C33
10, 1W
R43
L1
C31
22uH
0.47uF, 400V
C27
0.1uF,100V
R41
C25
0.1uF
R32
2.7K
C19
0.1uF
R30
4.7R
24
D4
1N4148
D2
1N4148
25
26
27
VCC
18V-31V Version
47.5k 1%
47.5k 1%
R15
R16
R11
R12
C1
1nF
*3.01k 1%
CT_SGN D
R3
330
SC H_4312 Rev1.2
R4
CP1
2.2uF
CP2
R1100k
28
C21
29
GND
0.1uF,16V
30
DS2
VAA
C2
1nF
*3.01k 1%
CT_SGN D
330
2.2uF
1R
23
VS2
IC1
IR4312
VP2
OO
VS2
VB2
CSH2
COM
NC
NC
IN-23COMP 22CLIP
1
R26
10K
C15 1nF
R24
180R
R22
2.2nF,50V
C11
C12
C6
2.2nF,50V
GND
R8
220R 1W
GND
0.1uF, 63V
L2
R42
1R
VCC
22
VN2
31
GND
VSS
IN+2
5
6
4
180R
R19 180R
2.2nF,50V
C10
C7
Z2
2.2nF,50V
C5 10uF,10V
Z1
CT_SGND
5.1V
VSS
20
21
VS1
VN1
GND
-B
IN+1
IN-19COMP 1
VAA
7
10uF,10V
5.1V
VAA
INPUT GND
CSD11FAULT
8
10
12
C17
1nF
R23
180R
R20 180R
C14 2.2nF,50V
C13
2.2nF,50V
C9
C8
2.2nF,50V
2.2nF,50V
R7
220R 1W
R46 2.2k
D9
D8
C34
10, 1W
0.1uF, 63V
R44
C32
22uH
0.47uF, 400V
C28
0.1uF,100V
C26
0.1uF
C20
0.1uF
R33
2.7K
R31
4.7R
VP1
19
D5
VS1
D3
1N4148
18
VB1
17
CSH1
16
COM
15
VCC
14
NC
13
DS1
R27
10K
R25
47K
D1
D10
VSS
C16
22uF,16V
R21 180R
+B
47.5k 1%
R17
R13
R5
CP3
+B
R35
470R 1W
23
1N4148
R28
VAA
SD
47.5k 1%
R18
R14
C3
1nF
*3.01k 1%
*3.01k 1%
CT_SGN D
330
R6
330
2.2uF
2.2uF
CP4
R2100k
R34 4. 7k
Z3
11V
MJD44 H1 1 T4 G
1
Q1
CP5
R29
10K
4.7R
DS3
GND
C18
10uF,16V
C4
1nF
CT_SGN D
GND
22uF
Class D , AMP18 IR4312 Schemati c
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5
4
213
CN1
Fig 8
IRAUDAMP18 REV 1.0
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Bill of Materials
No Digikey P/N Designator Description Quantity Vender
1 399-1082-1-ND
2 587-2668-1-ND C5, C10 CAP CER 10UF 10V 10% X7R 0805 2 Digikey
3 490-1500-1-ND
4 587-1433-1-ND C16 CAP CER 22UF 16V 20% X5R 1206 1 Digikey
5 490-5519-1-ND C18 CAP CER 10UF 16V 10% X6S 0805 1 Digikey
6 311-1140-1-ND C19, C20 CAP CER 0.1UF 50V 10% X7R 0805 2 Digikey
7 311-1142-1-ND C21 CAP CER 0.1UF 16V 10% X7R 0805 1 Digikey
8 445-1418-1-ND C25, C26
9 445-1377-1-ND C27, C28, C36, C37
10 495-1315-ND C31, C32 CAP FILM 0.47UF 400VDC RADIAL 2 Digikey
11 BC2054-ND C33, C34 CAP FILM 0.1UF 63VDC RADIAL 2 Digikey
12 445-1418-1-ND C35
13 565-1064-ND C38, C39
14 CP1-3545N-ND CN1
15 565-1103-ND CP1, CP2, CP3, CP4 CAP ALUM 2.2UF 50V 20% RADIAL 4 Digikey
16 565-1056-ND CP5 CAP ALUM 22UF 25V 20% RADIAL 1 Digikey
17 1N4148W-FDICT-ND
18 160-1181-1-ND DS1 LED RED CLEAR 0603 SMD 1 Digikey
19 160-1183-1-ND DS2 LED GREEN CLEAR 0603 SMD 1 Digikey
20 160-1646-1-ND DS3 LED BLUE CLEAR 0603 SMD 1 Digikey
21 IR4312 IC1
22 Sagami 7G14A-220M-R L1, L2
23 281-1414-ND P1, P2, P3
24 MJD44H11T4GOSCT-ND Q1 TRANS PWR NPN 8A 80V DPAK 1 Digikey
25 MMBT5551FSCT-ND Q2, Q3 TRANSISTOR NPN 160V SOT-23 2 Digikey
26 RMCF0603JT100KCT-ND R1, R2
27 RMCF0603JT330RCT-ND R3, R4, R5, R6 RES 330 OHM 1/10W 5% 0603 SMD 4 Digikey
28 RMCF2512JT220RCT-ND R7, R8 RES 220 OHM 1W 5% 2512 SMD 2 Digikey
29 RHM3.01KCRCT-ND R11, R12, R13, R14 RES 3.01K OHM 1/8W 1% 0805 SMD 4 Digikey
30 311-47.5KCRCT-ND R15, R16, R17, R18 RES 47.5K OHM 1/8W 1% 0805 SMD 4 Digikey
31 RHM180GCT-ND
32 RHM47KGCT-ND R25 RES 47K OHM 1/10W 5% 0603 SMD 1 Digikey
33 RHM10KGCT-ND R26, R27, R29 RES 10K OHM 1/10W 5% 0603 SMD 3 Digikey
34 RMCF0603JT4R70CT-ND R28, R30, R31 RES TF 1/10W 4.7 OHM 5% 0603 3 Digikey
35 RHM2.7KGCT-ND R32, R33 RES 2.7K OHM 1/10W 5% 0603 SMD 2 Digikey
36 311-4.7KARCT-ND R34 RES 4.7K OHM 1/8W 5% 0805 SMD 1 Digikey
37 PT470XCT-ND R35 RES 470 OHM 1W 5% 2512 SMD 1 Digikey
38 P1.0ACT-ND R41, R42 RESISTOR 1.0 OHM 1/8W 5% 0805 2 Digikey
39 541-10.0AFCT-ND R43, R44 RES 10.0 OHM 1W 1% 2512 SMD 2 Digikey
40 RMCF0805JT2K20CT-ND R45, R46 RES 2.2K OHM 1/8W 5% 0805 SMD 2 Digikey
41 541-10KVCT-ND R48, R49 RES 10K OHM 1/2W 5% 1210 SMD 2 Digikey
C1, C2, C3, C4, C15,
C17
C6, C7, C8, C9, C11,
C12, C13, C14
D1, D2, D3, D4, D5,
D10
R19, R20, R21, R22,
R23, R24
CAP CER 1000PF 50V 10% X7R
0603
CAP CER 2200PF 50V 10% X7R
0603
CAP CER 0.1UF 100V 10% X7R
0805 2 Digikey
CAP CER 0.1UF 100V 10% X7R
1206 4 Digikey
CAP CER 0.1UF 100V 10% X7R
0805
CAP ALUM 2200UF 25V 20%
RADIAL
CONN JACK STEREO R/A 5PIN
3.5MM
DIODE SWITCH 100V 400MW
SOD123 6 Digikey
2 CH PowIRaudio integrated Class D
IC
Power Inductors Class D Inductor
22uH
CONN TERM BLOCK PCB 5.0MM
2POS
RES 100K OHM 1/10W 5% 0603
SMD
RES 180 OHM 1/10W 5% 0603 SMD 6 Digikey
6 Digikey
8 Digikey
1 Digikey
2 Digikey
1 Digikey
1 IR
2
3 Digikey
2 Digikey
Inductors,
Inc
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IRAUDAMP18 REV 1.0
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42 RMCF0805JT10R0CT-ND R50 RES 10 OHM 1/8W 5% 0805 SMD 1 Digikey
43 RHM47KARCT-ND R51, R55, R57 RES 47K OHM 1/8W 5% 0805 SMD 3 Digikey
44 RHM10KARCT-ND R52, R53, R56 RES 10K OHM 1/8W 5% 0805 SMD 3 Digikey
45 360-1758-ND S1
46 DDZ5V1BDICT-ND Z1, Z2
47 BZT52C11-FDICT-ND Z3 DIODE ZENER 11V 500MW SOD123 1 Digikey
48 568-3766-1-ND Z4
49 BZT52C16-FDICT-ND Z5
SWITCH TOGGLE SPDT .4VA SEAL
PCB 1 Digikey
DIODE ZENER 5.1V 500MW SOD123 2 Digikey
DIODE ZENER 33V 375MW
SOD123F 1 Digikey
DIODE ZENER 16V 500MW SOD123 1 Digikey
PCB Specifications
PCB:
1. Two Layers SMT PCB with through holes
2. 1/16 thickness
3. 2/0 OZ Cu
4. FR4 material
5. 10 mil lines and spaces
6. Solder Mask to be Green enamel EMP110 DBG (CARAPACE) or Enthone Endplate
DSR-3241or equivalent.
7. Silk Screen to be white epoxy non conductive per IPC–RB 276 Standard.
8. All exposed copper must finished with TIN-LEAD Sn 60 or 63 for 100u inches thick.
9. Tolerance of PCB size shall be 0.010 –0.000 inches
10. Tolerance of all Holes is -.000 + 0.003”
11. PCB acceptance criteria as defined for class II PCB’S standards.
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IRAUDAMP18 REV 1.0
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PCB Layout
Top side:
Bottom side:
Fig9
Note: Refer to AN1170 for footprint and board mounting details.
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Fig10
IRAUDAMP18 REV 1.0
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Revision changes descriptions
Revision Changes description Date
Rev 1.0 Released May 11, 16 2012
WORLD HEADQUARTERS: 101 N. Sepulveda Blvd., El Segundo, California 90245 Tel: (310) 252-7105
Data and specifications subject to change without notice. 05/16/2012
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IRAUDAMP18 REV 1.0
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Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
International Rectifier:
IRAUDAMP18
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