www.irf.com Page 1 of 46
IRAUDAMP6 REV 1
.0
IRAUDAMP6
250W/8Ω x 2 Channel Class D Audio Power Amplifier
Using the IRS20957S and IRF6785
By
Jun Honda, Jorge Cerezo and Liwei Zheng
CAUTION:
International Rectifier suggests the following guidelines for safe operation and handling of
IRAUDAMP6 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
www.irf.com Page 2 of 46
IRAUDAMP6 REV 1
.0
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
CLASS D OPERATION..................................................................................................................................... 13
POWER SUPPLIES.......................................................................................................................................... 13
BUS PUMPING ............................................................................................................................................... 14
HOUSE KEEPING POWER SUPPLY................................................................................................................... 14
INPUT............................................................................................................................................................ 15
OUTPUT ........................................................................................................................................................ 15
LOAD IMPEDANCE .......................................................................................................................................... 15
GAIN SETTING / VOLUME CONTROL ................................................................................................................ 16
EFFICIENCY................................................................................................................................................... 16
OUTPUT FILTER DESIGN AND PREAMPLIFIER................................................................................................... 17
SELF-OSCILLATING PWM MODULATOR .......................................................................................................... 17
ADJUSTMENTS OF SELF-OSCILLATING FREQUENCY......................................................................................... 18
SWITCHES AND INDICATORS ........................................................................................................................... 18
STARTUP AND SHUTDOWN ............................................................................................................................. 18
CLICK AND POP NOISE REDUCTION ............................................................................................................... 19
STARTUP AND SHUTDOWN SEQUENCING ........................................................................................................ 20
SELECTABLE DEAD-TIME................................................................................................................................ 23
LEVEL SHIFTERS ........................................................................................................................................... 23
PROTECTION SYSTEM OVERVIEW ................................................................................................................... 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
www.irf.com Page 3 of 46
IRAUDAMP6 REV 1
.0
Introduction
The IRAUDAMP6 reference design is a two-channel, 250W/ch (8Ω) 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: 250W x 2 channels (8Ω load),
Residual Noise: 90µV, IHF-A weighted, AES-17 filter
Distortion: 0.005% THD+N @ 125W, 8Ω
Efficiency: 96% @ 250W, 8Ω, single-channel driven, Class D stage
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
DC-protection (DCP),
Over-temperature protection (OTP)
PWM Modulator: Self-oscillating half-bridge topology with optional clock synchronization
Specifications
General Test Conditions (unless otherwise noted) Notes / Conditions
Supply Voltages ±73.5V
Load Impedance 8-4Ω
Self-Oscillating Frequency 400kHz No input signal, Adjustable
Gain Setting 33dB 1Vrms input yields rated power
Electrical Data Typical Notes / Conditions
IR Devices Used 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
www.irf.com Page 4 of 46
IRAUDAMP6 REV 1
.0
Rated Load Impedance 8-4Ω Resistive load
Idling Supply Current ±85mA No input signal
Total Idle Power Consumption 11.9W No input signal
Channel Efficiency 96% Single-channel driven,
250W, Class D stage
.
Audio Performance
*
Before
Demodula
tor
Class D
Output
Notes / Conditions
THD+N, 1W
THD+N, 10W
THD+N, 60W
THD+N, 100W
THD+N, 200W
0.008%
0.003%
0.0015%
0.002%
0.009%
0.008%
0.004%
0.002%
0.004%
0.009%
1kHz, Single-channel driven
Dynamic Range 117dB 113dB A-weighted, AES-17 filter,
Single-channel operation
Residual Noise, 22Hz - 20kHzAES17 70µV
110µV
Self-oscillating – 400kHz
Damping Factor 2000 906 1kHz, relative to 8Ω load
Channel Separation 92dB
90dB
72dB
92dB
80dB
62dB
100Hz
1kHz
10kHz
Frequency Response : 20Hz-20kHz
: 20Hz-35kHz
N/A ±0.25dB
±1dB 1W, 8Ω Load
Thermal Performance
Typical
Notes / Conditions
Idling T
C
=30°C
T
PCB
=36°C
No signal input, T
A
=25°C
2ch x 31.25W (1/8 rated power) T
C
=54°C
T
PCB
=65°C
Continuous, T
A
=25°C
2ch x 250W (Rated power) T
C
=80°C
T
PCB
=106°C
At OTP shutdown @ 150 sec,
T
A
=25°C
Physical Specifications
Dimensions 7.76”(L) x 5.86”(W) x 2.2”(H)
192 mm (L) x 149mm (W) x56mm(H)
Weight 0.54kgm
www.irf.com Page 5 of 46
IRAUDAMP6 REV 1
.0
Connection Setup
Fig 1 Typical Test Setup
Volume
J7 J9
J1 J5
J3
R100
S1
S2
CH1 Output CH2 Output
CH1
Input
CH2
Input
G
Protection
Normal
S3
73.5V,8A DC supply
8~4 Ohm 8~4 Ohm
73.5V,8A DC supply
J6
Audio Signal Generator
J8
250W,Non-inductive Resistors
www.irf.com Page 6 of 46
IRAUDAMP6 REV 1
.0
Connector Description
CH1 IN J7 Analog input for CH1
CH2 IN J9 Analog input for CH2
POWER J3 Positive and negative supply (+B / -B)
CH1 OUT J1 Output for CH1
CH2 OUT J5 Output for CH2
EXT CLK J6 External clock sync
DCP OUT
J8 DC protection relay output
Test Procedures
Test Setup:
1. Connect 8Ω-250 W dummy loads to output connectors (J1 and J5 as shown on Fig 1) and
parallel it with input of Audio Precision analyzer (AP).
2. Connect the Audio Signal Generator to J7 and J9 for CH1 and CH2 respectively (AP).
3. Set up the dual power supply with voltages of ±73.5V;set current limit to 8A.
4. TURN OFF the dual power supply before connecting to ON of the unit under test (UUT).
5. Set switch S1 to middle position (self oscillating).
6. Set volume level knob R130 fully counter-clockwise (minimum volume).
7. Connect the dual power supply to J3. as shown on Fig 1
Power up:
8. Turn ON the dual power supply. The ±B supplies must be applied and removed at the
same time.
9. Red LED (Protection) should turn on almost immediately and turn off after about 3s.
10. Green LED (Normal) then turns on after red LED is extinguished and should stay on.
11. Quiescent current for the positive supply should be 84mA ±10mA at +73.5V.
12. Quiescent current for the negative supply should be 80mA ±10mA at –73.5V.
13. Push S3 switch(Trip and Reset push-buttom)to restart the sequence of LEDs
indicators,which should be the same as noted above in steps 9-10.
Switching Frequency test
14. Monitor switching waveform at VS1/J4(pin9-12)of CH1 and VS2/J3(pin1-4)CH2 on
Daughter Board using an Oscilloscope.
15. For IRAUDAMP6, the self-oscillating switching frequency is pre-calibrated to 400 KHz. To
modify the IRAUDAMP6 frequency, change the values of potentiometers R49 and R74 for
CH1 and CH2 respectively.
www.irf.com Page 7 of 46
IRAUDAMP6 REV 1
.0
Functionality Audio Tests:
16. Apply 1V RMS at 1kHz sinusoidal signal from the Audio Signal Generator.
17. Turn control volume up (R130 clock-wise) to obtain an output reading of 250Watts.
18. For all subsequent tests as shown on the Audio Precision graphs below (Fig 2- Fig7), the
measurements are taken across J1 and J5 with an AES-17 Filter. Observe that a 1 V
RMS
input generates an output voltage of 44.7 V
RMS
.
19. Sweep the audio signal voltage from 15 mV
RMS
to 1 V
RMS
.
20. Monitor the output signals at J1/J5 with an oscilloscope. The waveform must be a non
distorted sinusoidal signal.
Test Setup using Audio Precision (Ap):
21. Use an unbalanced-floating signal from the generator outputs.
22. Use balanced inputs taken across output terminals, J1 and J5.
23. Connect Ap frame ground to GND at terminal J7/J9.
24. Select the AES-17 filter(pull-down menu) for all the testing except frequency response.
25. Sweep the input signal voltage from 15 mV
RMS
to 1 V
RMS
.
26. Run Ap test programs for all subsequent tests as shown in Fig 2- Fig 7below.
Performance and test graphs
C o lo rS w e e p T r a c e L in e S t y l e T h i c k D a t a A x i s C o m m e n t
1 1 B l u e S o lid 2 A n l r . T H D + N R a t io L e ft C H 2
1 3 R e d S o lid 2 A n l r . T H D + N R a t io L e ft C H 1
0.001
1 0
0.002
0.005
0 . 0 1
0 . 0 2
0 . 0 5
0 . 1
0 . 2
0 . 5
1
2
5
%
1 0 0 m 1 k2 0 0 m 5 0 0 m 1 2 5 1 0 2 0 5 0 1 0 0 2 0 0 5 0 0
W
±B Supply = ±73.5V, 8 Ω Resistive Load
Fig 2 IRAUDAMP6, THD+N versus Power, Stereo, 8 Ω
www.irf.com Page 8 of 46
IRAUDAMP6 REV 1
.0
8 ohm load
4 ohm load
Fig 3 IRAUDAMP6, Frequency response
www.irf.com Page 9 of 46
IRAUDAMP6 REV 1
.0
.
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Red Solid 2 Anlr.THD+N Ratio Left 125W L
1 2 Blue Solid 2 Anlr.THD+N Ratio Left 125W R
2 1 Magenta Solid 2 Anlr.THD+N Ratio Left 25W L
2 2 Green Solid 1 Anlr.THD+N Ratio Left 25W R
0.0001
100
0.001
0.01
0.1
1
10
%
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Fig 4 THD+N Ratio vs. Frequency
www.irf.com Page 10 of 46
IRAUDAMP6 REV 1
.0
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Magenta Solid 1 Fft.Ch.1 Ampl Left
1 2 Blue Solid 1 Fft.Ch.2 Ampl Left
-100
+0
-80
-60
-40
-20
d
B
V
10 20k20 50 100 200 500 1k 2k 5k 10k
Hz
Fig 5, 1V output Frequency Spectrum
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Red Solid 1 Fft.Ch.1 Ampl Left
1 2 Blue Solid 1 Fft.Ch.2 Ampl Left
-140
+20
-120
-100
-80
-60
-40
-20
+0
d
B
V
10 20k20 50 100 200 500 1k 2k 5k 10k
Hz
No signal, Self Oscillator @ 400kHz
Fig 6, IRAUDAMP6 Noise Floor
www.irf.com Page 11 of 46
IRAUDAMP6 REV 1
.0
.
Fig 7, Channel separation vs. frequency
.
www.irf.com Page 12 of 46
IRAUDAMP6 REV 1
.0
IRAUDAMP6 Overview
The IRAUDAMP6 features a 2CH self-oscillating type PWM modulator for the lowest component
count, highest performance and robust design. This topology represents an analog version of a
second-order sigma-delta modulation having a Class D switching stage inside the loop. The
benefit of the sigma-delta modulation, in comparison to the carrier-signal based modulation, is that
all the error in the audible frequency range is shifted to the inaudible upper-frequency range by
nature of its operation. Also, sigma-delta modulation allows a designer to apply a sufficient
amount of error correction.
The IRAUDAMP6 self-oscillating topology consists of following essential functional blocks.
• Front-end integrator
• PWM comparator
• Level shifters
• Gate drivers and MOSFETs
• Output LPF
IRF6785
Direct
-
FET
Feedback
GND
LPF
+B
-B
Σ
IRS20957S
Gate Driver
U1 U1
Daughter-board
Integrator
Fig 8, Simplified Block Diagram of Class D Amplifier
www.irf.com Page 13 of 46
IRAUDAMP6 REV 1
.0
Functional Descriptions
Class D Operation
Referring to CH1 as an example, the op-amp U6 forms a front-end second-order integrator with
C38, C42 & R50 + R49P. This integrator receives a rectangular feedback waveform from the
Class D switching stage and outputs a quadratic oscillatory waveform as a carrier signal. To
create the modulated PWM signal, the input signal shifts the average value of this quadratic
waveform (through gain relationship between R40,AR154 and R38 + R39) so that the duty varies
according to the instantaneous value of the analog input signal. The IRS20957 input comparator
processes the signal to create the required PWM signal. This PWM signal is internally level-shifted
down to the negative supply rail where this signal is split into two signals, with opposite polarity
and added deadtime, for high-side and low-side MOSFET gate signals, respectively. The
IRS20957 drives two IRF6785 DirectFET MOSFETs in the power stage to provide the amplified
PWM waveform. The amplified analog output is re-created by demodulating the amplified PWM.
This is done by means of the LC low-pass filter (LPF) formed by L4 and C34, which filters out the
Class D switching carrier signal.
Power Supplies
The IRAUDAMP6 has all the necessary housekeeping power supplies onboard and only requires
a pair of symmetric power supplies ranging from ±38 V to ±82 V (+B, GND, -B) for operation. The
internally-generated housekeeping power supplies include a ±5 V supply for analog signal
processing (preamp, etc.), while a +12 V supply (V
CC
), referenced to –B, is included to supply the
Class D gate-driver stage.
For the externally-applied power, a regulated power supply is preferable for performance
measurements, but not always necessary. The bus capacitors, C45 ~ C48 on the motherboard,
along with high-frequency bypass-caps C19 ~ C26 on daughter board, address the high-frequency
ripple current that result from switching action. In designs involving unregulated power supplies,
the designer should place a set of bus capacitors, having enough capacitance to handle the audio-
ripple current, externally. Overall regulation and output voltage ripple for the power supply design
are not critical when using the IRAUDAMP6 Class D amplifier as the power supply rejection ratio
(PSRR) of the IRAUDAMP6 is excellent (Fig 9).
www.irf.com Page 14 of 46
IRAUDAMP6 REV 1
.0
Fig 9, Amp6 Power Supply Rejection Ratio (PSRR)
Bus Pumping
Since the IRAUDAMP6 is a half-bridge configuration, bus pumping does occur. Under normal
operation during the first half of the cycle, energy flows from one supply through the load and into
the other supply, thus causing a voltage imbalance by pumping up the bus voltage of the receiving
power supply. In the second half of the cycle, this condition is opposite, resulting in bus pumping
of the other supply.
These conditions worsen bus pumping:
– Lower frequencies (bus-pumping duration is longer per half cycle)
– Higher power output voltage and/or lower load impedance (more energy transfers between
supplies)
– Smaller bus capacitors (the same energy will cause a larger voltage increase)
The IRAUDAMP6 has protection features that will shutdown the switching operation if the bus
voltage becomes too high (>82 V) or too low (<36 V). One of the easiest countermeasures is to
drive both of the channels out of phase so that one channel consumes the energy flow from the
other and does not return it to the power supply. Bus voltage detection is only done on the –B
supply as the effect of the bus pumping on the supplies is assumed to be symmetrical in amplitude
(although opposite in phase).
House Keeping Power Supply
The internally-generated housekeeping power supplies include ±5V for analog signal processing,
and +12V supply (V
CC
) referred to the negative supply rail -B for DirectFET gate drive. The gate
driver section of the IRS20957 uses VCC to drive gates of the DirectFETs. V
CC
is referenced to –
B (negative power supply). D6, R4 and C15 form a bootstrap floating supply for the HO gate
driver.
www.irf.com Page 15 of 46
IRAUDAMP6 REV 1
.0
Input
A proper input signal is an analog signal ranging from 20Hz to 20kHz with up to 3 V
RMS
amplitude
with a source impedance of no more than 600 Ω. Input signal with frequencies from 30kHz to
60kHz may cause LC resonance in the output LPF, causing a large reactive current flowing
through the switching stage, and the LC resonance can activate OCP.
The IRAUDAMP6 has an RC network called a Zobel network (R45 and C36) to damp the
resonance and prevent peaking frequency response with light loading impedance. (Fig 10), but is
not thermally rated to handle continuous supersonic frequencies. These supersonic input
frequencies therefore should be avoided. Separate mono RCA connectors provide input to each of
the two channels. Although both channels share a common ground, it is necessary to connect
each channel separately to limit noise and crosstalk between channels.
Output
Both outputs for the IRAUDAMP6 are single-ended and therefore have terminals labeled (+) and (-
) with the (-) terminal connected to power ground. Each channel is optimized for a 8 Ω speaker
load for a maximum output power of 250 W.
Load Impedance
Each channel is optimized for a 8 Ω speaker load in half bridge.
Fig 10 Output Low Pass Filter and Zobel Network
www.irf.com Page 16 of 46
IRAUDAMP6 REV 1
.0
Gain Setting / Volume Control
The IRAUDAMP6 has an internal volume control (potentiometer R130 labeled, “VOLUME”) for
gain adjustment. Gain settings for both channels are tracked and controlled by the volume control
IC (U_2) setting the gain from the microcontroller IC (U_3). The total gain is a product of the
power-stage gain, which is constant (+33 dB), and the input-stage gain that is directly-controlled
by the volume adjustment. The volume range is about 100 dB with minimum volume setting to
mute the system with an overall gain of less than -60 dB. For best performance in testing, the
internal volume control should be set to 1 Vrms input will result in rated output power (250 W into
8 Ω).
Efficiency
Fig 11 shows efficiency characteristics of the IRAUDAMP6. The high efficiency is achieved by
following major factors:
1) Low conduction loss due to the DirectFETs offering low R
DS(ON)
2) Low switching loss due to the DirectFETs offering low input capacitance for fast rise and
fall times
Secure dead-time provided by the IRS20957, avoiding cross-conduction
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 50 100 150 200 250 300 350 400
Output Power(W)
Efficiency (%)
Class D Efficiency
Fig 11, IRAUDAMP6 8 ohms load Stereo, ±B supply = ±73.5V
www.irf.com Page 17 of 46
IRAUDAMP6 REV 1
.0
Output Filter Design and Preamplifier
The audio performance of the IRAUDAMP6 depends on a number of different factors. The section
entitled, “Typical Performance” presents performance measurements based on the overall system,
including the preamp and output filter. While the preamp and output filter are not part of the Class
D power stage, they have a significant effect on the overall performance.
Output filter
The amplified PWM output is reconstructed back to an analog signal by the output LC LPF.
Demodulation LC low-pass filter (LPF) formed by L4 and C34, filters out the Class D switching
carrier signal leaving the audio output at the speaker load. A single stage output filter can be used
with switching frequencies of 400 kHz and greater; a design with a lower switching frequency may
require an additional stage of LPF.
Since the output filter is not included in the control loop of the IRAUDAMP6, the reference design
cannot compensate for performance deterioration due to the output filter. Therefore, it is important
to understand what characteristics are preferable when designing the output filter:
1) The DC resistance of the inductor should be minimal and be within 20 m_Ohm or less.
2) The linearity of the output inductor and capacitor should be high with respect to load
current and voltage.
Preamplifier
The preamp allows partial gain of the input signal, and in the IRAUDAMP6, controls the volume.
The preamp itself will add distortion and noise to the input signal, resulting in a gain through the
Class D output stage and appearing at the output. Even a few micro-volts of noise can add
significantly to the output noise of the overall amplifier. In fact, the output noise from the preamp
contributes more than half of the overall noise to the system.
It is possible to evaluate the performance without the preamp and volume control, by moving
resistors R154and R155 to R157 and R156, respectively. This effectively bypasses the preamp
and connects the RCA inputs directly to the Class D power stage input. Improving the selection of
preamp and/or output filter, will improve the overall system performance to approach that of the
stand-alone Class D power stage.
Self-Oscillating PWM Modulator
The IRAUDAMP6 Class D audio power amplifier features a self-oscillating type PWM modulator
for the lowest component count and robust design. This topology represents an analog version of
a second-order sigma-delta modulation having a Class D switching stage inside the loop. The
benefit of the sigma-delta modulation, in comparison to the carrier-signal based modulation, is that
all the error in the audible frequency range is shifted to the inaudible upper-frequency range by
nature of its operation. Also, sigma-delta modulation allows a designer to apply a sufficient
amount of correction.
The self-oscillating frequency is determined by the total delay time inside the control loop of the
system. The delay of the logic circuits, the IRS20957 gate-driver propagation delay, the IRF6785
switching speed, the time-constant of front-end integrator (e.g. R50 + R49, C38 and C42 for CH1)
www.irf.com Page 18 of 46
IRAUDAMP6 REV 1
.0
and variations in the supply voltages are critical factors of the self-oscillating frequency. Under
normal conditions, the switching-frequency is around 400 kHz with no audio input signal and a +/-
73.5 V supply.
Adjustments of Self-Oscillating Frequency
The PWM switching frequency in this type of self-oscillating switching scheme greatly impacts the
audio performance, both in absolute frequency and frequency relative to the other channels. In
absolute terms, at higher frequencies, distortion due to switching-time becomes significant, while
at lower frequencies, the bandwidth of the amplifier suffers. In relative terms, interference between
channels is most significant if the relative frequency difference is within the audible range.
Normally when adjusting the self-oscillating frequency of the different channels, it is best to either
match the frequencies accurately, or have them separated by at least 25 kHz.
Potentiometers for adjusting self-oscillating frequency
R49 Switching frequency for CH1*
R74 Switching frequency for CH2*
*Adjustments have to be done at an idling condition with no signal input.
Switches and Indicators
There are two different indicators on the reference design:
– A Red LED, signifying a fault / shutdown condition when lit.
– A green LED on the motherboard, signifying conditions are normal and no fault condition is
present.
There are three switches on the reference design:
– Switch S1 is an oscillator selector. This three-position switch is selectable for internal self-
oscillator (middle position – “SELF”), or either internal (“INT”) or external (“EXT”) clock
synchronization.
– Switch S2 is an internal clock-sync phase difference selector. This feature allows the designer
to modify the clock-sync phase separation in order to avoid synchronized switching noise
interference. With S2 is set to OFF, the sync-clock phase difference value is 180°.With S2 is
set to INT, the clock-sync phase is set by potentiometer R100. With S2 is set to STG, one
channel’s clock is quadrature-lagging
– Switch S3 is a trip and reset push-button. Pushing this button has the same effect of a fault
condition. The circuit will restart about three seconds after the shutdown button is released.
Startup and Shutdown
One of the most important aspects of any audio amplifier is the startup and shutdown procedures.
Typically, transients occurring during these intervals can result in audible pop- or click-noise on the
output speaker. Traditionally, these transients have been kept away from the speaker through the
use of a series relay that connects the speaker to the audio amplifier only after the startup
transients have passed and disconnects the speaker prior to shutting down the amplifier. It is
interesting to note that the audible noise of the relay opening and closing is not considered “click
noise”, although in some cases, it can be louder than the click noise of non-relay-based solutions.
www.irf.com Page 19 of 46
IRAUDAMP6 REV 1
.0
The IRAUDAMP6 does not use any series relay to disconnect the speaker from the audible
transient noise, but rather a shunt-based click noise reduction circuit that yields audible noise
levels that are far less that those generated by the relays they replace. This results in a more
reliable, superior performance system.
For the startup and shutdown procedures, the activation (and deactivation) of the click-noise
reduction circuit, the Class D power stage and the audio input (mute) controls have to be
sequenced correctly to achieve the required click noise reduction. The overall startup sequencing,
shutdown sequencing and shunt circuit operation are described below.
Click and POP Noise Reduction
To reduce the turn-on and turn-off click noise, a low impedance shunting circuit is used to
minimize the voltage across the speaker during transients. For this purpose, the shunting circuit
must include the following characteristics:
1) An impedance significantly lower than that of the speaker being shunted. In this case, the
shunt impedance is ~100 mΩ, compared to the normal 8 Ω speaker impedance.
2) When deactivated, the shunting circuit must be able to block voltage in both directions due
to the bi-directional nature of the audio output.
3) The shunt circuit requires some form of OCP. If one of the Class D output MOSFETs fails,
or is conducting when the speaker mute (SP MUTE) is activated, the shunting circuit will
effectively try to short one of the two supplies (+/-B).
The implemented click-noise reduction circuit is shown in Figure 12. Before startup or shutdown of
the Class D power stage, the click-noise reduction circuit is activated through the SP MUTE
control signal. With SP MUTE signal high, the speaker output is shorted through the back-to-back
MOSFETs (U5 for Channel 1) with an equivalent on resistance of about 100 mΩ. The two
transistors (U7 for Channel 1) are for the OCP circuit.
+B
-B
Speaker Mute
Fig 12, Class D Output Stage with Click-Noise Reduction Circuit
Over Current
Protection
Click noise
reduction circuit
Transient
current paths
www.irf.com Page 20 of 46
IRAUDAMP6 REV 1
.0
Startup and Shutdown Sequencing
The IRAUDAMP6 sequencing is achieved through the charging and discharging of the CStart
capacitor C66. This, coupled to the charging and discharging of the voltage of CSD (C11 on
daughter board for CH1) of the IRS20957, is all that is required for complete sequencing. The
conceptual startup and shutdown timing diagrams are show in Figure 13.
Fig 13, Conceptual Startup Sequencing of Power Supplies and Audio Section Timing
V
CC
-B
+B
+5 V
-5 V
CStart
CSD
UVP@-20 V
CSD= 2/3V
DD
CStart Ref2 CStart Ref1
Audio MUTE
SP MUTE
CHx_O
Class D startup
Time
Music startup
www.irf.com Page 21 of 46
IRAUDAMP6 REV 1
.0
For startup sequencing, +/-B supplies startup at different intervals. As +/-B supplies reach +5 V
and -5 V respectively, the analog supplies (+/-5 V) start charging and, once +B reaches ~16 V, V
CC
charges. Once –B reaches -20 V, the UVP is released and CSD and CStart start charging. Once
+/-5 V is established, the click-noise reduction circuit is activated through the SP MUTE control
signal. As CSD reaches two-thirds V
DD
, the Class D stage starts oscillating. Once the startup
transient has passed, SP MUTE is released (CStart reaches Ref1). The Class D amplifier is now
operational, but the preamp output remains muted until CStart reaches Ref2. At this point, normal
operation begins. The entire process takes less than three seconds.
Fig 14, Conceptual Shutdown Sequencing of Power Supplies and Audio Section Timing
Shutdown sequencing is initiated once UVP is activated. As long as the supplies do not discharge
too quickly, the shutdown sequence can be completed before the IRS20957 trips UVP. Once UVP
is activated, CSD and CStart are discharged at different rates. In this case, threshold Ref2 is
reached first and the preamp audio output is muted. Once CStart reaches threshold Ref1, the
click-noise reduction circuit is activated (SP MUTE). It is then possible to shutdown the Class D
stage (CSD reaches two-thirds V
DD
). This process takes less than 200 ms.
V
CC
-B
+B
+5 V
-5 V
CStart
CSD
UVP@-20 V
CSD= 2/3V
DD
CStart Ref1
CStart Ref2
Audio MUTE
SP MUTE
CHx_O
Class D shutdown
Time
Music shutdown
www.irf.com Page 22 of 46
IRAUDAMP6 REV 1
.0
For any external fault condition (OTP, OVP, UVP or DCP – see “Protection”) that does not lead to
power supply shutdown, the system will trip in a similar manner as described above. Once the
fault is cleared, the system will reset (similar sequence as startup).
Fig 15, Conceptual Click Noise Reduction Sequencing at Trip and Reset
CStart
CSD
External trip
CSD= 2/3VDD
CStart Ref1
CStart Ref2
SP MUTE
CHx_O
Audio MUTE
Class D shutdown
Time
Music shutdown
Class D startup
Music startup
CStart Ref1 CStart Ref2
Reset
www.irf.com Page 23 of 46
IRAUDAMP6 REV 1
.0
Selectable Dead-time
The IRS20957 determines its dead-time based on the voltage applied to the DT pin. An internal
comparator translates which pre-determined dead-time is being used by comparing the DT voltage
with internal reference voltages. A resistive voltage divider from V
CC
sets threshold voltages for
each setting, negating the need for a precise absolute voltage to set the mode. The threshold
voltages between dead-time settings are set internally, based on different ratios of V
CC
as
indicated in the diagram below. In order to avoid drift from the input bias current of the DT pin, a
bias current of greater than 0.5 mA is suggested for the external resistor divider circuit. Suggested
values of resistance that are used to set a dead-time are given below. Resistors with up to 5%
tolerance can be used.
Dead-time mode Dead-time R22 R19 DT Voltage
DT1 ~15 ns <10kΩ Open V
CC
DT2 ~25 ns 5.6kΩ 4.7kΩ 0.46(V
CC
)
DT3 ~35 ns 8.2kΩ 3.3kΩ 0.29(V
CC
)
DT4 ~45 ns Open <10kΩ COM
Recommended Resistor Values for Dead Time Selection
Vcc 0.57 xVcc 0.36 xVcc 0.23 xVcc
45 nS
35nS
25nS
15nS
V
DT
Dead-time
Fig 17 Dead-time Settings vs. V
DT
Voltage
Level Shifters
The internal input level-shifter transfers the PWM signal down to the low-side gate driver section.
The gate driver section has another level-shifter that level shifts up the high-side gate signal to the
high-side gate driver section.
www.irf.com Page 24 of 46
IRAUDAMP6 REV 1
.0
Protection System Overview
The IRS20957 integrates over current protection (OCP) inside the IC. The rest of the protections,
such as over-voltage protection (OVP), under-voltage protection (UVP), and over temperature
protection (OTP), are detected externally to the IRS20957.
Fig 18, Functional Block Diagram of Protection Circuit Implementation
The external shutdown circuit will disable the output by pulling down CSD pins . If the fault
condition persists, the protection circuit stays in shutdown until the fault is removed.
.
Over-Current Protection (OCP)
The OCP internal to the IRS20957 shuts down the IC if an OCP is sensed in either of the output
MOSFETs. For a complete description of the OCP circuitry, please refer to the IRS20957
datasheet. Here is a brief description:
www.irf.com Page 25 of 46
IRAUDAMP6 REV 1
.0
Low-Side Current Sensing
The low-side current sensing feature protects the low side DirectFET from an overload condition
from negative load current by measuring drain-to-source voltage across R
DS(ON)
during its on state.
OCP shuts down the switching operation if the drain-to-source voltage exceeds a preset trip level.
The voltage setting on the OCSET pin programs the threshold for low-side over-current sensing.
When the VS voltage becomes higher than the OCSET voltage during low-side conduction, the
IRS20957 turns the outputs off and pulls CSD down to -VSS.
Fig 19 Simplified Functional Block Diagram of Low-Side Current Sensing
High-Side Current Sensing
The high-side current sensing protects the high side DirectFET from an overload condition from
positive load current by measuring drain-to-source voltage across R
DS(ON)
during its on state. OCP
shuts down the switching operation if the drain-to-source voltage exceeds a preset trip level.
High-side over-current sensing monitors drain-to-source voltage of the high-side DirectFET during
the on state through the CSH and VS pins. The CSH pin detects the drain voltage with reference
to the VS pin, which is the source of the high-side DirectFET. In contrast to the low-side current
sensing, the threshold of the CSH pin to trigger OC protection is internally fixed at 1.2V. An
external resistive divider R30, R32 and R34 are used to program a threshold . An external reverse
blocking diode D8 is required to block high voltage feeding into the CSH pin during low-side
conduction. By subtracting a forward voltage drop of 0.6V at D8, the minimum threshold which can
be set for the high-side is 0.6V across the drain-to-source.
www.irf.com Page 26 of 46
IRAUDAMP6 REV 1
.0
Over-Voltage Protection (OVP)
OVP is provided externally to the IRS20957. OVP shuts down the amplifier if the bus voltage
between GND and -B exceeds 82V. The threshold is determined by a Zener diode Z9. OVP
protects the board from harmful excessive supply voltages, such as due to bus pumping at very
low frequency-continuous output in stereo mode.
Under-Voltage Protection (UVP)
UVP is provided externally to the IRS20957. UVP prevents unwanted audible noise output from
unstable PWM operation during power up and down. UVP shuts down the amplifier if the bus
voltage between GND and -B falls below a voltage set by Zener diode Z8.
IRS20957S
Fig 20, Simplified Functional Block Diagram of High-Side Current Sensing
www.irf.com Page 27 of 46
IRAUDAMP6 REV 1
.0
Speaker DC-Voltage Protection (DCP)
DCP protects speakers against DC output current feeding to its voice coil. DC offset detection
detects abnormal DC offset and shuts down PWM. If this abnormal condition is caused by a
MOSFET failure because one of the high-side or low-side MOSFETs short circuited and remained
in the on state, the power supply needs to be cut off in order to protect the speakers. Output DC
offset greater than ±2.1V triggers DCP.
Offset Null (DC Offset) Adjustment
The IRAUDAMP6 is designed such that no output-offset nullification is required. DC offsets are
tested to be less than ±5 mV.
.
Over-Temperature Protection (OTP)
A separate PTC resistor is placed in close proximity to the high-side IRF6785 DirectFET MOSFET
for each of the amplifier channels. If the resistor temperature rises above 90 °C, the OTP is
activated. The OTP protection will only shutdown the relevant channel by pulling low the CSD pin
and will recover once the temperature at the PTC has dropped sufficiently. This temperature
protection limit yields a PCB temperature at the MOSFET of about 100 °C. This setting is limited
by the PCB material and not by the operating range of the MOSFET.
Thermal Considerations
With this high efficiency, the IRAUDAMP6 design can handle one-eighth of the continuous rated
power, which is generally considered to be a normal operating condition for safety standards.
Without increasing the size of a heatsink or forced air-cooling, the daughter board cannot handle
continuous rated power.
www.irf.com Page 28 of 46
IRAUDAMP6 REV 1
.0
Thermal Interface Material’s Pressure Control
The DirectFET MOSFETs are attached to a heatsink with a thermal interface material (TIM). The
pressure between DirectFET and TIM is controlled by depth of Heat Spreader’s groove. Choose
TIM which is recommended by IR. (Refer to AN-1035 for more details). TIM’s manufacturer
thickness, conductivity, & etc. determine pressure requirement. Below shows selection options
recommended:
Fig
21,
TIM Information
www.irf.com Page 29 of 46
IRAUDAMP6 REV 1
.0
Check the TIM’s compression deflection with constant rate of strain (example as Fig.10) base on
manufacturer’s datasheet. According to the stress requirement, find strain range for the TIM. Then,
calculate heat spreader groove depth as below:
Groove Depth=DirectFET’s Height +TIM’s Thickness*strain
**DirectFET’s height should be measured from PCB to the top of DirectFET after reflow. The
average height of IRF6785 is 0.65mm.
Fig 22, compression deflection with constant rate of strain
www.irf.com Page 30 of 46
IRAUDAMP6 REV 1
.0
AMP6 Thermal pad pressure control calculation
PCB thickness=1.6mm
Heatsink thickness=2.54mm Weight=27.1g
(DCC58375837L-18B
http://www.alphanovatech.com/c_dcc5837ue.html
)
Thermal Pad thickness=2.03mm
(BER164-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_butto
n&KeyWords=BER164-ND+)
Spring : S001YJ1D FL=6.4mm SL=2.9mm (http://www.alphanovatech.com/c_springe.html)
Pressure Required:10-50psi(Fig21)
Clearance between push pin and heatsink:
1, Without Spring:
Pin height-PCB thickness-heatsink height(substructure height)-thermal pad thickness
=8.5-1.6-2.54-2.03=2.33mm
2, With Spring:( Assumption: pressure=50pci strain=30% according to Fig22)
Pin height-PCB thickness-heatsink height(substructure height)-thermal pad thickness*70%
=8.5-1.6-2.54-1.421=2.939mm=expected length
Spring length change=Free length-expected length=6.4-2.939=3.461mm
Spring strength= Spring length change*spring rate=3.461*5.19=17.96N
Strength to PCB=4* Spring strength+(heatsink weight*0.00098)=4*17.96+27.1*0.00098=71.87N
To have 50psi pressure we need strength as below:
1kg/cm^2=14.21psi; 1g/cm^2=0.0098N/cm^2
=>50psi=3.51kg/cm^2=3.51*1000*0.0098nN/cm^2=34.398N/cm^2
Heatsink S=5.79*3.68cm^2=21.31cm^2
Total strength we need=34.398*21.31N=732.93N>>71.87N
=>So spring does not have enough strength support push pin more than solid height.
Then, spring height=solid height
Clearance between push pin and heatsink=2.9mm
Pin height-PCB thickness-heatsink height (substructure height)-thermal pad thickness*X%
X=72%
According to Fig22
When Strain=28%, Stress=45psi within the required range 10-50psi
www.irf.com Page 31 of 46
IRAUDAMP6 REV 1
.0
Short Circuit Protection Response
Figs 23-24 show over current protection reaction time of the IRAUDAMP6 in a short circuit event.
As soon as the IRS20957 detects an over current condition, it shuts down PWM. After one
second, the IRS20957 tries to resume the PWM. If the short circuit persists, the IRS20957 repeats
try and fail sequences until the short circuit is removed.
Short Circuit in Positive and Negative Load Current
Fig 23, Positive and Negative OCP Waveforms
.
OCP Waveforms Showing CSD Trip and Hiccup
Fig 24 OCP Response with Continuous Short Circuit
Load current
CSD pin
VS pin
Load current
CSD pin
VS pin
Load current
CSD pin
Load current
VS pin
CSD pin
VS pin
Load current
VS pin
Load current
VS pin
Positive OCP
Negative OCP
www.irf.com Page 32 of 46
IRAUDAMP6 REV 1
.0
Schematic
www.irf.com Page 33 of 46
IRAUDAMP6 REV 1
.0
www.irf.com Page 34 of 46
IRAUDAMP6 REV 1
.0
www.irf.com Page 35 of 46
IRAUDAMP6 REV 1
.0
www.irf.com Page 36 of 46
IRAUDAMP6 REV 1
.0
Fig 22 IRAUDAMP6 Schematic
www.irf.com Page 37 of 46
IRAUDAMP6 REV
1.0
IRAUDAMP6 Fabrication Materials
Table 1 IRAUDAMP6 Mother board’s Materials
No P/N Designator Description Quantity Vendor
1 565-1106-ND C1, C33, C50, C75, C77
CAP 10UF 50V ELECT SMG
RAD 5 Digikey
2 PCC13491CT-ND C2, C82, C83
CAP 10UF 16V CERAMIC X7R
1206 3 Digikey
3 565-1147-ND C3, C6, C23, C84, C85, C86
CAP 4.7UF 100V ELECT SMG
RAD 6 Digikey
4 490-1857-1-ND C4, C7, C24
CAP CER 1.0UF 100V 10% X7R
1210 3 Digikey
5 490-1644-1-ND C9, C11, C25
CAP CER 22000PF 50V 5% C0G
0805 3 Digikey
6 478-1403-1-ND C10, C13, C26
CAP CERM .47UF 10% 16V X7R
0805 3 Digikey
7 490-1864-1-ND C12, C16, C27
CAP CER 4.7UF 50V 10% X7R
1210 3 Digikey
8 445-2685-1-ND C14, C19, C28
CAP CER 8200PF 50V C0G 5%
0805 3 Digikey
9 PCC1982CT-ND C15, C20, C29
CAP 330PF 100V CERAMIC
X7R 0805 3 Digikey
10 478-3772-1-ND C17, C21, C30
CAP CERM 6800PF 5% 50V
X7R 0805 3 Digikey
11 478-3746-1-ND C18, C22, C31
CAP CERM 2200PF 5% 100V
X7R 0805 3 Digikey
12 445-2378-1-ND C32, C49
CAP CER 150PF 3000V C0G
10% 1812 2 Digikey
13 338-1178-ND C34, C51
CAP .33UF 2000VDC POLY
FILM AXL 2 Digikey
14 PCE3101CT-ND C35, C64, C65, C69, C79 CAP 10UF 16V ELECT FC SMD 5 Digikey
15 495-1311-ND C36, C53
CAP .10UF 400V METAL
POLYPRO 2 Digikey
16 PCC2009CT-ND C38, C42, C56, C60
CAP CERAMIC 1000PF 200V
NP0 1206 4 Digikey
17 PCC1931CT-ND C39, C57
CAP 2.2UF 16V CERAMIC X7R
1206 2 Digikey
18 478-1281-1-ND C40, C58
CAP CERM 33PF 5% 100V NP0
0805 2 Digikey
19 445-1432-1-ND C41, C43, C59, C61
CAP CER 3.3UF 50V X7R 20%
1210 4 Digikey
20 565-1161-ND C45, C46, C47, C48
CAP 1200UF 100V ELECT SMG
RAD 4 Digikey
21 PCC1812CT-ND C62, C63, C68, C78
CAP .1UF 16V CERAMIC X7R
0805 4 Digikey
22 565-1037-ND C66
CAP 100UF 16V ELECT SMG
RAD 1 Digikey
23 445-1418-1-ND C67
CAP CER .10UF 100V X7R 10%
0805 1 Digikey
24 PCC101CGCT-ND C70
CAP 100PF 50V CERM CHIP
0805 SMD 1 Digikey
25 493-1042-ND C71
CAP 330UF 16V ELECT VR
RADIAL 1 Digikey
26 445-2322-1-ND C72, C73
CAP CER 2200PF 100V C0G 5%
0805 2 Digikey
27 PCC103BNCT-ND C80
CAP 10000PF 50V CERM CHIP
0805 1 Digikey
28 B180DICT-ND D1, D2, D4
DIODE SCHOTTKY 80V 1A
SMA 3 Digikey
29 B1100-FDICT-ND D3
DIODE SCHOTTKY 100V 1A
SMA 1 Digikey
30 641-1166-1-ND D5, D6, D13, D14
DIODE STANDARD 2A 400V
SMB 4 Digikey
31 1N4148WDICT-ND D7, D8, D9, D10, D12, D15, D16, DIODE SWITCH 100V 400MW 8 Digikey
www.irf.com Page 38 of 46
IRAUDAMP6 REV
1.0
D17 SOD-123
32 1N5819HW-FDICT-ND D11, D18
DIODE SCHOTTKY 40V 1A
SOD123 2 Digikey
33 1N4148WTPMSCT-ND D19, D20, D21, D22
DIODE SWITCH 100V 150MA
SOD123 4 Digikey
34 RS1DB-FDICT-ND D23
DIODE FAST REC 200V 1A
SMB 1 Digikey
35 277-1271-ND J1, J5
CONN TERM BLOCK 2POS
9.52MM PCB 2 Digikey
36 A26453-ND J2
CONN RECEPT 6POS .100
VERT DUAL 1 Digikey
37 277-1272-ND J3
CONN TERM BLOCK 3POS
9.52MM PCB 1 Digikey
38 A26454-ND J4
CONN RECEPT 8POS .100
VERT DUAL 1 Digikey
39 A32248-ND J6
CONN JACK BNC R/A 50 OHM
PCB TIN 1 Digikey
40 CP-1418-ND J7, J9
CONN RCA JACK R/A BLACK
PCB 2 Digikey
41 N/A J8
TERMINAL BLOCK 7.50MM
VERT 2POS 1 Digikey
42 A26453-ND J10
CONN RECEPT 6POS .100
VERT DUAL 1 Digikey
43 513-1051-1-ND L1, L2, L3
INDUCTOR SHIELD PWR
470UH SMD 3 Digikey
44 7G31A-220M-R L4, L5 Class D Inductor,22uH 2 Inductors, Inc
45 160-1143-ND NORMAL1
LED 3MM GREEN
TRANSPARENT 1 Digikey
46 N/A P1
Power MOSFET Photovoltaic
Relay 1 IR
47 160-1140-ND PROTECTION1
LED 3MM HI-EFF RED
TRANSPARENT 1 Digikey
48 FZT855CT-ND Q1, Q3
TRANS NPN 150V 4000MA
SOT-223 2 Digikey
49 MMBTA92DICT-ND Q2
TRANSISTOR PNP -300V SOT-
23 1 Digikey
50 MMBT5401DICT-ND Q7, Q10, Q13
TRANS 150V 350MW PNP SMD
SOT-23 3 Digikey
51 MMBT5551-7DICT-ND Q8, Q9, Q11, Q12, Q14, Q15, Q17
TRANS 160V 350MW NPN SMD
SOT-23 7 Digikey
52 PZT2222ACT-ND Q18
TRANS AMP NPN GP 40V .5A
SOT-223 1 Digikey
53
PZT2907AT1GOSCT-
ND Q20
TRANS SS SW PNP 600MA 60V
SOT223 1 Digikey
54 PT10XCT-ND R1, R4, R9, R14, R30 RES 10 OHM 1W 5% 2512 SMD 5 Digikey
55 P10KACT-ND R2, R3, R5, R7, R84, R92, R99
RES 10K OHM 1/8W 5% 0805
SMD 7 Digikey
56 P20KACT-ND R6, R142
RES 20K OHM 1/8W 5% 0805
SMD 2 Digikey
57 P47ACT-ND
R56, R79, R82, R88, R101, R107,
R133, R134, R135
RES 47 OHM 1/8W 5% 0805
SMD 9 Digikey
58 RHM8.66KCRCT-ND R10
RES 8.66K OHM 1/8W 1% 0805
SMD 1 Digikey
59 P18.7KCCT-ND R11, R17, R32
RES 18.7K OHM 1/8W 1% 0805
SMD 3 Digikey
60 P1.00KCCT-ND R13
RES 1.00K OHM 1/8W 1% 0805
SMD 1 Digikey
61 P4.7KCCT-ND R15, R31
RES 4.70K OHM 1/8W 1% 0805
SMD 2 Digikey
62 P20.5KCCT-ND R16, R19, R37
RES 20.5K OHM 1/8W 1% 0805
SMD 3 Digikey
63 P1.00KCCT-ND R18, R36
RES 1.00K OHM 1/8W 1% 0805
SMD 2 Digikey
64 P100KACT-ND
R20, R21, R22, R47, R53, R60, R61,
R87, R91, R108, R109, R112, R116,
R117, R118, R119, R132, R136
RES 100K OHM 1/8W 5% 0805
SMD 15 Digikey
www.irf.com Page 39 of 46
IRAUDAMP6 REV
1.0
65 PPC100KW-3JCT-ND R38, R62
RES 100K OHM METAL FILM
3W 5% 2 Digikey
66 P1.0KECT-ND R39, R63
RES 1.0K OHM 1/4W 5% 1206
SMD 2 Digikey
67 P3.3KZCT-ND R40, R64
RES 3.3K OHM 1/10W .1% 0805
SMD 2 Digikey
68 P22KACT-ND R41, R55, R57, R65, R67, R73
RES 22K OHM 1/8W 5% 0805
SMD 6 Digikey
69 P0.0ACT-ND R42, R66
RES 0.0 OHM 1/8W 5% 0805
SMD 2 Digikey
70 PT2.2KXCT-ND R43, R68
RES 2.2K OHM 1W 5% 2512
SMD 2 Digikey
71 PT10XCT-ND R45, R70 RES 10 OHM 1W 5% 2512 SMD 2 Digikey
72 311-470ARCT-ND R46, R71
RES 470 OHM 1/8W 5% 0805
SMD 2 Digikey
73 P4.7ACT-ND R48, R54, R72, R78
RESISTOR 4.7 OHM 1/8W 5%
0805 4 Digikey
74 3361P-102GCT-ND R49, R74
TRIMPOT 1K OHM 6MM SQ
SMD 2 Digikey
75 P100ECT-ND R50, R75, R80, R90, R94
RES 100 OHM 1/4W 5% 1206
SMD 5 Digikey
76 P1.0KACT-ND
R51, R52, R76, R77, R104, R106,
R121, R138
RES 1.0K OHM 1/8W 5% 0805
SMD 8 Digikey
77 P200KACT-ND R58, R59
RES 200K OHM 1/8W 5% 0805
SMD 2 Digikey
78 P33KACT-ND R81
RES 33K OHM 1/8W 5% 0805
SMD 1 Digikey
79 P47KACT-ND
R83, R86, R93, R95, R96, R105,
R111, R123, R129, R139, R140
RES 47K OHM 1/8W 5% 0805
SMD 11 Digikey
80 P68KACT-ND R85, R97
RES 68K OHM 1/8W 5% 0805
SMD 2 Digikey
81 P4.7KACT-ND R89
RES 4.7K OHM 1/8W 5% 0805
SMD 1 Digikey
82 P100ACT-ND R98, R114, R131
RES 100 OHM 1/8W 5% 0805
SMD 3 Digikey
83 3362H-502LF-ND R100
POT 5.0K OHM 1/4" SQ CERM
SL ST 1 Digikey
84 P330ACT-ND R102
RES 330 OHM 1/8W 5% 0805
SMD 1 Digikey
85 P82KACT-ND R103
RES 82K OHM 1/8W 5% 0805
SMD 1 Digikey
86 P5.76KFCT-ND
R110, R113, R120, R124, R126,
R127
RES 5.76K OHM 1/4W 1% 1206
SMD 6 Digikey
87 P10ECT-ND R115
RES 10 OHM 1/4W 5% 1206
SMD 1 Digikey
88 P0.0ECT-ND R122, R128
RES ZERO OHM 1/4W 5% 1206
SMD 2 Digikey
89 P3G7103-ND R130
POT 10K OHM 9MM VERT
MET BUSHING 1 Digikey
90 RMCF1/100RCT-ND R141, R148, R151 RES 0.0 OHM 1/8W 0805 SMD 3 Digikey
91 P47.5KCCT-ND R144, R145, R146
RES 47.5K OHM 1/8W 1% 0805
SMD 3 Digikey
92 PT10XCT-ND R147, R149, R150 RES 10 OHM 1W 5% 2512 SMD 3 Digikey
93 open R152 0ohm for 1kw 1 Digikey
94 P0.0ACT-ND R153
RES 1.0K OHM 1/8W 5% 0805
SMD 1 Digikey
95 311-1.0KARCT-ND R154, R155
RES 1.0K OHM 1/8W 5% 0805
SMD 2 Digikey
96 open R156, R157 Bypass vol ctrl 2
97 EG1944-ND S1, S2
SWITCH SLIDE DP3T .2A
L=6MM 2 Digikey
98 P8010S-ND S3 6MM LIGHT TOUCH SW H=5 1 Digikey
99 LM5574MT-ND U2, U3, U4
IC REG BUCK 75V 0.5A 16-
TSSOP 3 Digikey
100
IRF7380 U5, U9 80V DUAL N MOSFET SO8 2 IR
www.irf.com Page 40 of 46
IRAUDAMP6 REV
1.0
101
AD825ARZ-ND U6, U11
IC AMP JFET HS GEN-PURP 8-
SOIC 2 Digikey
102
XN0121500LCT-ND U7, U10
TRANS ARRAY NPN/NPN
W/RES MINI5P 2 Digikey
103
296-1089-1-ND U8, U12
IC SINGLE INVERTER GATE
SOT23-5 2 Digikey
104
296-11643-1-ND U13
DUAL 4-BIT BINARY
COUNTERS 1 Digikey
105
300-8001-1-ND U14 OSCILLATOR 1.5440 MHZ SMT 1 Digikey
106
296-1194-1-ND U_1
IC HEX SCHMITT-TRIG INV
14-SOIC 1 Digikey
107
3310IR02 U_2 Stand-alone Controller 1 Tachyonix
108
598-1599-ND U_3
Amplifiers - Audio Stereo Digital
Volume Control 1 Digikey/Mouser
109
BZT52C15-7DICT-ND Z1
DIODE ZENER 15V 500MW
SOD-123 1 Digikey
110
MMSZ5263BT1OSCT-
ND Z2, Z3
DIODE ZENER 500MW 56V
SOD123 2 Digikey
111
BZT52C5V1-7DICT-ND Z4
DIODE ZENER 5.1V 500MW
SOD-123 1 Digikey
112
BZT52C15-FDICT-ND Z5, Z6
DIODE ZENER 500MW 15V
SOD123 2 Digikey
113
BZT52C18-FDICT-ND Z7
DIODE ZENER 500MW 18V
SOD123 1 Digikey
114
BZT52C36-7DICT-ND Z8
DIODE ZENER 36V 500MW
SOD-123 1 Digikey
115
MMSZ5268BT1GOSCT-
ND Z9
DIODE ZENER 82V 500MW
SOD-123 1 Digikey
116
BZT52C5V6-FDICT-ND Z10, Z12
DIODE ZENER 5.6V 500MW
SOD123 2 Digikey
Table 2 IRAUDAMP6 Daughter board’s Materials
No P/N Designator Description Quantity Vendor
1
445-2276-1-ND C1, C2, C3, C4
CAP CER 47000PF 100V X7R
10%0805 4 Digikey
2
PCC470CGCT-ND C5, C6
CAP 47PF 50V CERM CHIP 0805
SMD 2 Digikey
3
587-1329-1-ND C9, C10, C13, C14 CAP CER 2.2UF 25V X7R 1206 4 Digikey
4
399-3706-1-ND C11, C12
CAPACITOR TANT 10UF 16V
10% SMD 2 Digikey
5
445-1607-1-ND C15, C16
CAP CER 22UF 25V X7R 20%
1812 2 Digikey
6
445-2296-1-ND C17, C18
CAP CER .22UF 250V X7R 10%
1210 2 Digikey
7
445-2300-1-ND
C19, C20, C21, C22, C23, C24, C25,
C26
CAP CER .10UF 630V X7R 10%
1812 8 Digikey
8
B130LAW-FDICT-ND D2, D3
DIODE SCHOTTKY 1A 30V
SOD123 2 Digikey
9
1N4148WTPMSCT-ND D4, D5
DIODE SWITCH 100V 150MA
SOD123 2 Digikey
10
ES1D-FDICT-ND D6, D7
DIODE ULTRA FAST 1A 200V
SMA 2 Digikey
11
BAV21W-FDICT-ND D8, D9
DIODE SWITCH 200V 250MW
SOD123 2 Digikey
12
2011-03-ND J1, J2
CONN HEADER .100 DUAL STR
6POS 2 Digikey
13
2011-04-ND J3
CONN HEADER .100 DUAL STR
8POS 1 Digikey
14
MMBT5551-7DICT-ND Q1, Q4
TRANS 160V 350MW NPN SMD
SOT-23 2 Digikey
15
MMBT5401DICT-ND Q2, Q3
TRANS 150V 350MW PNP SMD
SOT-23 2 Digikey
16
IRF6785M Q5, Q6, Q7, Q8 DirectFET M-Case 4 IR
www.irf.com Page 41 of 46
IRAUDAMP6 REV
1.0
17
P100KACT-ND R1, R3, R5, R7, R9, R11
RES 100K OHM 1/8W 5% 0805
SMD 6 Digikey
18
P10KACT-ND R2, R8, R30, R31
RES 10K OHM 1/8W 5% 0805
SMD 4 Digikey
19
P1.0KACT-ND R4, R6
RES 1.0K OHM 1/8W 5% 0805
SMD 2 Digikey
20
RHM9.1KARCT-ND R12, R13
RES 9.1K OHM 1/8W 5% 0805
SMD 2 Digikey
21
P100ACT-ND R14, R15
RES 100 OHM 1/8W 5% 0805
SMD 2 Digikey
22
RHM18KERCT-ND R16, R17
RES 18K OHM 1/4W 5% 1206
SMD 2 Digikey
23
RHM1.2KARCT-ND R18, R20
RES 1.2K OHM 1/8W 5% 0805
SMD 2 Digikey
24
P8.2KACT-ND R19, R21
RES 8.2K OHM 1/8W 5% 0805
SMD 2 Digikey
25
P3.3KACT-ND R22, R23
RES 3.3K OHM 1/8W 5% 0805
SMD 2 Digikey
26
P4.7ACT-ND R24, R25
RESISTOR 4.7 OHM 1/8W 5%
0805 2 Digikey
27
P10ACT-ND R26, R27, R36, R37, R38, R39 RES 10 OHM 1/8W 5% 0805 SMD 6 Digikey
28
P33KACT-ND R28, R29
RES 33K OHM 1/8W 5% 0805
SMD 2 Digikey
29
RHM2.2KARCT-ND R32, R33
RES 2.2K OHM 1/8W 5% 0805
SMD 2 Digikey
30
RHM7.5KARCT-ND R34, R35
RES 7.5K OHM 1/8W 5% 0805
SMD 2 Digikey
31
P1.0PCT-ND R40, R41
RES 1.0 OHM 1/4W 5% 1206
SMD 2 Digikey
32
P0.0ACT-ND R42, R43
RES 0.0 OHM 1/8W 5% 0805
SMD 2 Digikey
33
594-2381-675-20907 Rp1, Rp2 Thermistors PTC Temp Prot. 100 C 2 Mouser
34
IRS20957S U1, U2 IC GATE DRIVER 2 IR
Table 3 IRAUDAMP6 Mechanical Bill of Materials
No P/N Description Quantity Vendor
1 BER229-ND THERMAL PAD 8"X16" .080" GP1500 Digikey
2
DCC5837U-
18B Heat Sink 57.9 x 36.8 x 17.8 1 Alpha Novatech Inc.
3 S001YZ1H PIP 3.175*8.5[TH] 4 Alpha Novatech Inc.
4 S001YJ1D Spring 4 Alpha Novatech Inc.
www.irf.com Page 42 of 46
IRAUDAMP6 REV
1.0
IRAUDAMP6 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.
Gerber Files Apertures Description:
All Gerber files stored in the attached CD-ROM were generated from Protel Altium Designer
Altium Designer 6. Each file name extension means the following:
1. .gtl Top copper, top side
2. .gbl Bottom copper, bottom side
3. .gto Top silk screen
4. .gbo Bottom silk screen
5. .gts Top Solder Mask
6. .gbs Bottom Solder Mask
7. .gko Keep Out,
8. .gm1 Mechanical1
9. .gd1 Drill Drawing
10. .gg1 Drill locations
11. .txt CNC data
12. .apr Apertures data
Additional files for assembly that may not be related with Gerber files:
13. .pcb PCB file
14. .bom Bill of materials
15. .cpl Components locations
16. .sch Schematic
17. .csv Pick and Place Components
18. .net Net List
19. .bak Back up files
20. .lib PCB libraries
www.irf.com Page 43 of 46
IRAUDAMP6 REV
1.0
Fig 25 IRAUDAMP6 Mother board PCB Top Overlay (Top View)
www.irf.com Page 44 of 46
IRAUDAMP6 REV
1.0
Fig 26 IRAUDAMP6 Mother board PCB Bottom Layer (Top View)
www.irf.com Page 45 of 46
IRAUDAMP6 REV
1.0
Fig 27 IRAUDAMP6 Daughter board PCB Top Overlay (Top View)
Fig 28 IRAUDAMP6 Daughter board PCB Bottom Layer (Top View)
www.irf.com Page 46 of 46
IRAUDAMP6 REV
1.0
Revision changes descriptions
Revision Changes description Date
Rev 1.0 Released May, 30 2010
WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105
Data and specifications subject to change without notice. 01/29/2009
