TABLE OF CONTENTS
PAGE
INTRODUCTION............................................................................................................................................... 3
SPECIFICATIONS ............................................................................................................................................ 3
CONNECTION SETUP ..................................................................................................................................... 5
CONNECTOR DESCRIPTION ......................................................................................................................... 6
TEST PROCEDURES....................................................................................................................................... 6
PERFORMANCE AND TEST GRAPHS .......................................................................................................... 7
IRAUDAMP6 OVERVIEW .............................................................................................................................. 12
FUNCTIONAL DESCRIPTIONS..................................................................................................................... 13
C
LASS
D O
PERATION
..................................................................................................................................... 13
P
OWER
S
UPPLIES
.......................................................................................................................................... 13
B
US
P
UMPING
............................................................................................................................................... 14
H
OUSE
K
EEPING
P
OWER
S
UPPLY
................................................................................................................... 14
I
NPUT
............................................................................................................................................................ 15
O
UTPUT
........................................................................................................................................................ 15
L
OAD
I
MPEDANCE
.......................................................................................................................................... 15
G
AIN
S
ETTING
/ V
OLUME
C
ONTROL
................................................................................................................ 16
E
FFICIENCY
................................................................................................................................................... 16
O
UTPUT
F
ILTER
D
ESIGN AND
P
REAMPLIFIER
................................................................................................... 17
S
ELF
-O
SCILLATING
PWM M
ODULATOR
.......................................................................................................... 17
A
DJUSTMENTS OF
S
ELF
-O
SCILLATING
F
REQUENCY
......................................................................................... 18
S
WITCHES AND
I
NDICATORS
........................................................................................................................... 18
S
TARTUP AND
S
HUTDOWN
............................................................................................................................. 18
C
LICK AND
POP N
OISE
R
EDUCTION
............................................................................................................... 19
S
TARTUP AND
S
HUTDOWN
S
EQUENCING
........................................................................................................ 20
S
ELECTABLE
D
EAD
-
TIME
................................................................................................................................ 23
L
EVEL
S
HIFTERS
........................................................................................................................................... 23
P
ROTECTION
S
YSTEM
O
VERVIEW
................................................................................................................... 24
Over-Current Protection (OCP)............................................................................................................... 24
Over-Voltage Protection (OVP)............................................................................................................... 26
Under-Voltage Protection (UVP) ............................................................................................................. 26
Speaker DC-Voltage Protection (DCP) ................................................................................................... 27
Offset Null (DC Offset) Adjustment ......................................................................................................... 27
Over-Temperature Protection (OTP) ...................................................................................................... 27
Thermal Considerations .......................................................................................................................... 27
Thermal Interface Material’s Pressure Control ....................................................................................... 28
AMP6 Thermal pad pressure control calculation .................................................................................... 30
Short Circuit Protection Response .......................................................................................................... 31
IRAUDAMP6 FABRICATION MATERIALS................................................................................................... 37
IRAUDAMP6 PCB SPECIFICATIONS........................................................................................................... 42
REVISION CHANGES DESCRIPTIONS........................................................................................................ 46
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IRAUDAMP6 REV 1
.0
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Introduction
The IRAUDAMP6 reference design is a two-channel, 250W/ch (8 ) load half-bridge Class D audio power
amplifier. This reference design demonstrates how to use the IRS20957S Class D audio controller and gate
driver IC, implement protection circuits, and design an optimum PCB layout using the IRF6785 DirectFET
MOSFETs. This reference design does not require increasing the size of the heatsink or require 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
•
•
•
•
•
•
AV receivers
Home theater systems
Mini component stereos
Powered speakers
Sub-woofers
Musical Instrument amplifiers
Features
Output Power:
Residual Noise:
Distortion:
Efficiency:
Multiple Protection Features:
250W x 2 channels (8 load),
90µV, IHF-A weighted, AES-17 filter
0.005% THD+N @ 125W, 8
96% @ 250W, 8 , single-channel driven, Class D stage
Over-current protection (OCP), high side and low side
Over-voltage protection (OVP),
Under-voltage protection (UVP), high side and low side
DC-protection (DCP),
Over-temperature protection (OTP)
Self-oscillating half-bridge topology with optional clock synchronization
PWM Modulator:
Specifications
General Test Conditions (unless otherwise noted)
Supply Voltages
±73.5V
Load Impedance
8-4
Self-Oscillating Frequency
400kHz
Gain Setting
33dB
Electrical Data
IR Devices Used
Notes / Conditions
No input signal, Adjustable
1Vrms input yields rated power
Typical
Notes / Conditions
IRS20957S Audio Controller and Gate-Driver,
IRF6785 DirectFET MOSFETs
Modulator
Self-oscillating, second order sigma-delta modulation, analog input
Power Supply Range
± 38V to ±75V
Bipolar power supply
Output Power CH1-2: (1% THD+N)
320W
1kHz
Output Power CH1-2: (10% THD+N)
410W
1kHz
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IRAUDAMP6 REV 1
.0
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Rated Load Impedance
Idling Supply Current
Total Idle Power Consumption
Channel Efficiency
.
8-4
±85mA
11.9W
96%
Resistive load
No input signal
No input signal
Single-channel driven,
250W, Class D stage
Audio Performance
*
Before
Demodula
tor
0.008%
0.003%
0.0015%
0.002%
0.009%
117dB
70µV
2000
92dB
90dB
72dB
N/A
Class D
Output
0.008%
0.004%
0.002%
0.004%
0.009%
113dB
110µV
906
92dB
80dB
62dB
±0.25dB
±1dB
Notes / Conditions
THD+N, 1W
THD+N, 10W
THD+N, 60W
THD+N, 100W
THD+N, 200W
Dynamic Range
Residual Noise, 22Hz - 20kHzAES17
Damping Factor
Channel Separation
1kHz, Single-channel driven
A-weighted, AES-17 filter,
Single-channel operation
Self-oscillating – 400kHz
1kHz, relative to 8
100Hz
1kHz
10kHz
1W, 8
Load
load
Frequency Response : 20Hz-20kHz
: 20Hz-35kHz
Thermal Performance
Idling
2ch x 31.25W (1/8 rated power)
2ch x 250W (Rated power)
Typical
T
C
=30°C
T
PCB
=36°C
T
C
=54°C
T
PCB
=65°C
T
C
=80°C
T
PCB
=106°C
Notes / Conditions
No signal input, T
A
=25°C
Continuous, T
A
=25°C
At OTP shutdown @ 150 sec,
T
A
=25°C
Physical Specifications
Dimensions
Weight
7.76”(L) x 5.86”(W) x 2.2”(H)
192 mm (L) x 149mm (W) x56mm(H)
0.54kgm
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IRAUDAMP6 REV 1
.0
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