IRAUDAMP8 - INTERNATIONAL RECTIFIER

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IRAUDAMP8 REV 1.0

IRAUDAMP8

120W x 4 Channel Class D Audio Power Amplifier

Using the IRS2093M and IRF6665

By

Jun Honda, Yasushi Nishimura and Liwei Zheng

CAUTION:

International Rectifier suggests the following guidelines for safe operation and handling of

IRAUDAMP8 Demo board;

 Always wear safety glasses whenever operating Demo Board

 Avoid personal contact with exposed metal surfaces when operating Demo Board

 Turn off Demo Board when placing or removing measurement probes

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IRAUDAMP8 REV 1.0

TABLE OF CONTENTS PAGE

INTRODUCTION............................................................................................................................................... 3

SPECIFICATIONS ............................................................................................................................................ 3

CONNECTION SETUP ..................................................................................................................................... 5

CONNECTOR DESCRIPTION ......................................................................................................................... 5

TEST PROCEDURES....................................................................................................................................... 6

PERFORMANCE AND TEST GRAPHS .......................................................................................................... 7

CLIPPING CHARACTERISTICS.................................................................................................................... 10

EFFICIENCY................................................................................................................................................... 11

THERMAL CONSIDERATIONS..................................................................................................................... 11

THERMAL INTERFACE MATERIAL’S PRESSURE CONTROL ................................................................................. 12

POWER SUPPLY REJECTION RATIO (PSRR)............................................................................................ 14

SHORT CIRCUIT PROTECTION RESPONSE .............................................................................................. 15

IRAUDAMP8 OVERVIEW .............................................................................................................................. 16

FUNCTIONAL DESCRIPTIONS..................................................................................................................... 18

IRS2093 GATE DRIVER IC ............................................................................................................................ 18

SELF-OSCILLATING FREQUENCY .................................................................................................................... 19

ADJUSTMENTS OF SELF-OSCILLATING FREQUENCY ......................................................................................... 19

SELECTABLE DEAD-TIME................................................................................................................................20

PROTECTION SYSTEM OVERVIEW ............................................................................................................ 21

CLICK AND POP NOISE REDUCTION ......................................................................................................... 23

BUS PUMPING............................................................................................................................................... 23

INPUT SIGNAL AND GAIN SETTING ........................................................................................................... 25

GAIN SETTING............................................................................................................................................... 25

SCHEMATIC…………………………………………………………………………………………………………. .26

IRAUDAMP8 FABRICATION MATERIALS................................................................................................... 27

IRAUDAMP8 HARDWARE ............................................................................................................................ 30

IRAUDAMP8 PCB SPECIFICATIONS........................................................................................................... 31

REVISION CHANGES DESCRIPTIONS........................................................................................................ 34

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IRAUDAMP8 REV 1.0

Introduction

The IRAUDAMP8 Demo board is a reference design which uses only one IC (IRS2093M) to derive

appropriate input signals, amplify the audio input, and achieve a four-channel 120 W/ch (4Ω) half-bridge

Class D audio power amplifier. The reference design demonstrates how to use the IRS2093M Class D audio

controller and gate driver IC, implement protection circuits, and design an optimum PCB layout using

IRF6665 DirectFET MOSFETs. The reference design contains all the required housekeeping power supplies

for ease of use. The four-channel design is scalable, for power and number of channels.

Applications

 AV receivers

 Home theater systems

 Mini component stereos

 Powered speakers

 Sub-woofers

 Musical Instrument amplifiers

 Automotive after market amplifiers

Features

Output Power: 120W x 4 channels,

Residual Noise: 200V, IHF-A weighted, AES-17 filter

Distortion: 0.012% THD+N @ 60W, 4Ω

Efficiency: 90% @ 120W, 4Ω, 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

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 ±35V

Load Impedance 4Ω

Self-Oscillating Frequency 400kHz No input signal, Adjustable

Gain Setting 26.5dB 1Vrms input yields rated power

Electrical Data Typical Notes / Conditions

IR Devices Used IRS2093M Audio Controller and Gate-Driver,

IRF6665 DirectFET MOSFETs

Modulator Self-oscillating, second order sigma-delta modulation, analog input

Power Supply Range ± 25V to ±35V Bipolar power supply

Output Power CH1-4: (1% THD+N) 120W 1kHz

Output Power CH1-4: (10% THD+N) 170W 1kHz

Rated Load Impedance 8-4Ω Resistive load

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IRAUDAMP8 REV 1.0

Standby Supply Current ±100mA No input signal

Total Idle Power Consumption 7W No input signal

Channel Efficiency 90% Single-channel driven,

120W, 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

0.015%

0.006%

0.005%

0.015%

0.008%

0.012%

0.02%

1kHz, Single-channel driven

Dynamic Range 101dB 101dB A-weighted, AES-17 filter,

Single-channel operation

Residual Noise, 22Hz - 20kHzAES17 200V

200V

Self-oscillating – 400kHz

Damping Factor 2000 48 1kHz, relative to 4Ω load

Channel Separation 85dB

85dB

75dB

78dB

77dB

70dB

100Hz

1kHz

10kHz

Frequency Response : 20Hz-20kHz

: 20Hz-35kHz

N/A ±1dB

±3dB 1W, 4Ω - 8Ω Load

Thermal Performance Typical Notes / Conditions

Idling TC =30C

TPCB=42C

No signal input, TA=25C

4ch x 15W (1/8 rated power) TC =54C

TPCB=71C

Continuous, TA=25C

4ch x 120W (Rated power) TC =80C

TPCB=106C

At OTP shutdown @ 150 sec,

TA=25C

Physical Specifications

Dimensions 3.94”(L) x 2.83”(W) x 0.85”(H)

100 mm (L) x 72 mm (W) x 21.5 mm(H)

Weight 0.140kgm

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IRAUDAMP8 REV 1.0

Connection Setup

Fig 1 Typical Test Setup

Connector Description

CH1 IN CN1 Analog input for CH1

CH2 IN CN1 Analog input for CH2

CH3 IN CN1 Analog input for CH3

CH4 IN CN1 Analog input for CH4

SUPPLY P1 Positive and negative supply (+B / -B)

CH1 OUT P2 Output for CH1

CH2 OUT P2 Output for CH2

CH3 OUT P3 Output for CH3

CH4 OUT P3 Output for CH4

250W,4ΩNon-inductive

CH1 CH2 CH3 CH4

IRS2093

CH2 CH1 +B GND -B CH4 CH3

Output

Input

G

DS1

35 V, 10 A DC supply

A

udio Si

g

nal Generato

r

Output

VR1

Frequency adjustor ,VCC INDICATOR

IRF6665

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IRAUDAMP8 REV 1.0

Test Procedures

Test Setup:

1. Connect 4-200 W dummy loads to 4 output connectors (P2 and P3 as shown on Fig 1)

and an Audio Precision analyzer (AP).

2. Connect the Audio Signal Generator to CN2 for CH1~CH4 respectively (AP).

3. Set up the dual power supply with voltages of ±35V; current limit to 10A.

4. TURN OFF the dual power supply before connecting to On of the unit under test (UUT).

5. Connect the dual power supply to P1. as shown on Fig 1

Power up:

6. Turn ON the dual power supply. The ±B supplies must be applied and removed at the

same time.

7. The Blue LED should turn ON immediately and stay ON

8. Quiescent current for the positive supply should be 100mA 10mA at +35V.

9. Quiescent current for the negative supply should be 115mA 10mA at –35V.

Switching Frequency test

10. With an Oscilloscope, monitor the switching waveform at test points VS1~VS4. Adjust VR1

to set the self oscillating frequency to 400 kHz  25 kHz.

Functionality Audio Tests:

11. Set the signal generator to 1kHz, 20 mVRMS output.

12. Connect the audio signal generator to CN2(Input of CH1,CH2,CH3,CH4)

13. Sweep the audio signal voltage from 15 mVRMS to 1 VRMS.

14. Monitor the output signals at P2/P3 with an oscilloscope. The waveform must be a non

distorted sinusoidal signal.

15. Observe that a 1 VRMS input generates an output voltage of 21.2 VRMS. The ratio,

R4A/(R3A), determines the voltage gain of IRAUDAMP8.

Test Setup using Audio Precision (Ap):

16. Use an unbalanced-floating signal from the generator outputs.

17. Use balanced inputs taken across output terminals, P2 and P3.

18. Connect Ap frame ground to GND at terminal P1.

19. Select the AES-17 filter(pull-down menu) for all the testing except frequency response.

20. Use a signal voltage sweep range from 15 mVRMS to 1 VRMS.

21. Run Ap test programs for all subsequent tests as shown in Fig 2- Fig 7below.

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IRAUDAMP8 REV 1.0

Performance and test graphs

0.001

10

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

%

100m 200200m 500m 1 2 5 10 20 50 100

W

CH1-Blue; CH2-Yellow; CH3-Red; CH4-Cyan

±B Supply = ±35V, 4 Ω Resistive Load

Fig 2 IRAUDAMP8, THD+N versus Power, Stereo, 4 Ω

.

-10

+4

-9

-8

-7

-6

-5

-4

-3

-2

-1

-0

+1

+2

+3

d

B

r

A

20 200k50 100 200 500 1k 2k 5k 10k 20k 50k 100k

Hz

T

CH1-Blue; CH2-Yellow; CH3-Red; CH4-Cyan

±B Supply = ±35V, 4 Ω Resistive Load

Fig 3 IRAUDAMP8, Frequency response

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IRAUDAMP8 REV 1.0

0.0001

100

0.0002

0.0005

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

%

20 20k50 100 200 500 1k 2k 5k 10k

Hz

Red CH1, 10W Output

Blue CH1, 50W Output

Fig 4 THD+N Ratio vs. Frequency

CH1-Blue; CH2-Yellow; CH3-Red; CH4-Cyan

Fig 5, 1V output Frequency Spectrum

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IRAUDAMP8 REV 1.0

CH1-Blue; CH2-Yellow; CH3-Red; CH4-Cyan

No signal, Self Oscillator @ 400kHz

Fig 6, IRAUDAMP8 Noise Floor

.

-120

+0

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

d

B

20 20k50 100 200 500 1k 2k 5k 10k

Hz

Red CH1 – CH2, 60W

Blue CH2 – CH1, 60W

Fig 7, Channel separation vs. frequency

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IRAUDAMP8 REV 1.0

Clipping characteristics

60W / 4, 1kHz, THD+N=0.012% 174W / 4, 1kHz, THD+N=10%

Measured Output and Distortion Waveforms

Fig 8 Clipping Characteristics

.

Red Trace: Total Distortion + Noise Voltage

Green Trace: Output Voltage

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IRAUDAMP8 REV 1.0

Efficiency

Fig 9 shows efficiency characteristics of the IRAUDAMP8. The high efficiency is achieved by

following major factors:

1) Low conduction loss due to the DirectFETs offering low RDS(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 IRS2093, avoiding cross-conduction

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 50 100 150

Output power (W)

Efficiency (%)

AMP8 35V 4ohms

Fig 9, IRAUDAMP8 4 ohms load Stereo, ±B supply = ±35V

Thermal Considerations

With this high efficiency, the IRAUDAMP8 design can handle one-eighth of the continuous rated

power, which is generally considered to be a normal operating condition for safety standards,

without additional heatsinks or forced air-cooling.

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IRAUDAMP8 REV 1.0

Thermal Interface Material’s Pressure Control

The pressure between DirectFET & TIM (Thermal Interface Material) 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 10 TIM Information

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IRAUDAMP8 REV 1.0

Check the TIM’s compression deflection with constant rate of strain (example as Fig.11) 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 IRF6665 is 0.6mm.

Fig 11 compression deflection with constant rate of strain

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IRAUDAMP8 REV 1.0

Power Supply Rejection Ratio (PSRR)

The IRAUDAMP8 obtains good power supply rejection ratio of -68 dB at 1kHz shown in Fig 12.

With this high PSRR, IRAUDAMP8 accepts any power supply topology when the supply voltages

fit between the min and max range.

ColorSweep Trace Line Style Thick Data Axis Comment

1 1 Red Solid 2 Anlr.Ampl Left

-90

+0

-80

-70

-60

-50

-40

-30

-20

-10

d

B

V

20 40k50 100 200 500 1k 2k 5k 10k 20k

Hz

Fig 12 Amp8 Power Supply Rejection Ratio (PSRR)

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IRAUDAMP8 REV 1.0

Short Circuit Protection Response

Figs 13-14 show over current protection reaction time of the IRAUDAMP8 in a short circuit event.

As soon as the IRS2093 detects an over current condition, it shuts down PWM. After one second,

the IRS2093 tries to resume the PWM. If the short circuit persists, the IRS2093 repeats try and fail

sequences until the short circuit is removed.

Short Circuit in Positive and Negative Load Current

Fig 13 Positive and Negative OCP Waveforms

.

OCP Waveforms Showing CSD Trip and Hiccup

Fig 14 OCP Response with Continuous Short Circuit

Load current

CSD

p

in

VS

p

in

Load current

CSD

p

in

VS

p

in

Load current

CSD

p

in

Load current

VS

p

in

CSD

p

in

VS

p

in

Load current

VS

p

in

Load current

VS

p

in

Positive OCP Negative OCP

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IRAUDAMP8 REV 1.0

IRAUDAMP8 Overview

The IRAUDAMP8 features a 4CH self-oscillating type PWM modulator for the smallest space,

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 IRAUDAMP8 self-oscillating topology consists of following essential functional blocks.

 Front-end integrator

 PWM comparator

 Level shifters

 Gate drivers and MOSFETs

 Output LPF

Integrator

Referring to Fig 15 below, the input operational amplifier of the IRS2093 forms a front-end second-

order integrator with R3, C2, C3, and R2. The integrator that receives a rectangular feedback

signal from the PWM output via R4 and audio input signal via R3 generates a quadratic carrier

signal at the COMP pin. The analog input signal shifts the average value of the quadratic

waveform such that the duty cycle varies according to the instantaneous voltage of the analog

input signal.

PWM Comparator

The carrier signal at the COMP pin is converted to a PWM signal by an internal comparator that

has a threshold at middle point between VAA and VSS. The comparator has no hysteresis in its

input threshold.

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.

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IRAUDAMP8 REV 1.0

Gate Drivers and DirectFETs

The received PWM signal is sent to the dead-time generation block where a programmable

amount of dead time is added into the PWM signal between the two gate output signals of LO and

HO to prevent potential cross conduction across the output power DirectFETs. The high-side level-

shifter shifts up the high-side gate drive signal out of the dead-time block.

Each channel of the IRS2093’s drives two DirectFETs, high- and low-sides, in the power stage

providing the amplified PWM waveform.

Output LPF

The amplified PWM output is reconstructed back to an analog signal by the output LC LPF.

Demodulation LC low-pass filter (LPF) formed by L1 and C13, 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.

Fig 15 Simplified Block Diagram of IRAUDAMP8 Class D Amplifier

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IRAUDAMP8 REV 1.0

Functional Descriptions

IRS2093 Gate Driver IC

The IRAUDAMP8 uses the IRS2093, a 4 Channel high-voltage (up to 200 V), high-speed power

MOSFET driver with internal dead-time and protection functions specifically designed for Class D

audio amplifier applications. These functions include OCP and UVP. The IRS2093 integrates bi-

directional over current protection for both high-side and low-side MOSFETs. The dead-time can

be selected for optimized performance according to the size of the MOSFET, minimizing dead-

time while preventing shoot-through. As a result, there is no gate-timing adjustment required

externally. Selectable dead-time through the DT pin voltage is an easy and reliable function which

requires only two external resistors, R12 and R13 as shown on Fig 16 or Fig 22 below.

The IRS2093 offers the following functions.

 PWM modulator

 Dead-time insertion

 Over current protection

 Under voltage protection

 Level shifters

Refer to IRS2093 datasheet and AN-1146 for more details.

Fig 16 System-level View of IRAUDAMP8

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IRAUDAMP8 REV 1.0

Self-Oscillating Frequency

Self-oscillating frequency is determined by the total delay time along the control loop of the

system; the propagation delay of the IRS2093, the DirectFETs switching speed, the time-constant

of front-end integrator (R2, R3, R4, C2, C3 ). Variations in +B and –B supply voltages also affect

the self-oscillating frequency.

The self-oscillating frequency changes with the duty ratio. The frequency is highest at idling. It

drops as duty cycle varies away from 50%.

Adjustments of Self-Oscillating Frequency

Use R2 to set different self-oscillating frequencies. 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 suggested to

either match the frequencies accurately, or have them separated by at least 25kHz. Under the

normal operating condition with no audio input signal, the switching-frequency is set around

400kHz in the IRAUDAMP8.

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IRAUDAMP8 REV 1.0

Selectable Dead-time

The dead-time of the IRS2093 is set based on the voltage applied to the DT pin. Fig 17 lists the

suggested component value for each programmable dead-time between 45 and 105 ns.

All the IRAUDAMP8 models use DT1 (45ns) dead-time.

Dead-time Mode R1 R2 DT/SD Voltage

DT1 <10k Open Vcc

DT2 5.6k 4.7k 0.46 x Vcc

DT3 8.2k 3.3k 0.29 x Vcc

DT4 Open <10k COM

Recommended Resistor Values for Dead Time Selection

Vcc 0.57 xVcc 0.36xVcc 0.23xVcc

105nS

85nS

65nS

45nS

VDT

Dead-time

Vcc

COM

DT

>0.5mA

R1

R2

IRS2093M

Fig 17 Dead-time Settings vs. VDT Voltage

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IRAUDAMP8 REV 1.0

Protection System Overview

The IRS2093 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 IRS2093 (Fig 18).

The external shutdown circuit will disable the output by pulling down CSD pins, (Fig 19). If the

fault condition persists, the protection circuit stays in shutdown until the fault is removed.

HT 1

OS

5

VT 3

GND 2

VCC

4

IC6

LM26CIM5-XHA

R51

22k

D51

4.7V

R52

15k

Q5

MMBT5551

R59

22k

Q3

MMBT5551

Q4

MMBT5551

R54

10k

R55

47k

R53

10k

R57

47k

R50

47k

R58

47k

Z3

39V

Z4

18V

OVP UVP

SD

R56

47k

R60

15k

GND

OTP

-B

Fig 18 DCP, OTP, UVP and OVP Protection Circuits

.

Fig 19 Simplified Functional Diagram of OCP

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IRAUDAMP8 REV 1.0

Over-Current Protection (OCP)

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 RDS(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

IRS2093 turns the outputs off and pulls CSD down to -VSS.

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 RDS(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 R15, R16 and R17 are used to program a threshold as shown in Fig 18.

An external reverse blocking diode D1 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 D1, the minimum

threshold which can be set for the high-side is 0.6V across the drain-to-source.

Over-Voltage Protection (OVP)

OVP is provided externally to the IRS2093. OVP shuts down the amplifier if the bus voltage

between GND and -B exceeds 39V. The threshold is determined by a Zener diode Z3. 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 IRS2093. 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 Z4.

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IRAUDAMP8 REV 1.0

Offset Null (DC Offset) Adjustment

The IRAUDAMP8 requires no output-offset adjustment. DC offsets are tested to be less than ±20

mV.

Over-Temperature Protection (OTP)

A Preset Thermostat IC, IC6 in Fig 17, is placed in close proximity to the heatsink which has 8

DirectFETs under it; and monitors heatsink temperature. If the heatsink temperature rises above

100 C, the OTP shuts down all 4 channels by pulling down the CSD pins of the IRS2093. OTP

recovers once the temperature has cooled down.

Click and POP Noise Reduction

Thanks to the click and pop elimination function built into the IRS2093, the IRAUDAMP8 does not

require any additional components for this function.

Power Supply Requirements

For convenience, the IRAUDAMP8 has all the necessary housekeeping power supplies onboard

and only requires a pair of symmetric power supplies. Or you can use it with the IRAUDPS1

reference design which is a 12 volt systems Audio Power Supply for automotive applications

designed to provide voltage rails (+B and –B) for Class D audio power amplifiers .

House Keeping Power Supply

The internally-generated housekeeping power supplies include ±5V for analog signal processing,

and +12V supply (VCC) referred to the negative supply rail -B for DirectFET gate drive. The gate

driver section of the IRS2093 uses VCC to drive gates of the DirectFETs. VCC is referenced to –B

(negative power supply). D2, R18 and C10 form a bootstrap floating supply for the HO gate driver.

Bus Pumping

When the IRAUDAMP8 is running in stereo mode, the bus pumping effect takes place with low

frequency, high output. Since the energy flowing in the Class D switching stage is bi-directional,

there is a period where the Class D amplifier feeds energy back to the power supply. The majority

of the energy flowing back to the supply is from the energy stored in the inductor in the output LPF.

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IRAUDAMP8 REV 1.0

Usually, the power supply has no way to absorb the energy coming back from the load.

Consequently the bus voltage is pumped up, creating bus voltage fluctuations.

Following conditions make bus pumping worse:

1. Lower output frequencies (bus-pumping duration is longer per half cycle)

2. Higher power output voltage and/or lower load impedance (more energy transfers between

supplies)

3. Smaller bus capacitance (the same energy will cause a larger voltage increase)

The OVP protects IRAUDAMP8 from failure in case of excessive bus pumping. One of the easiest

counter measures of bus pumping is to drive both of the channels in a stereo configuration 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 monitors only +B supply, assuming the bus pumping on the

supplies is symmetric in +B and -B supplies.

Blue: VS of CH3;Cyan: VS of CH2;Magenta: Voltage of +B;Green:Current of C13A

Fig 20 Auto-phase sync clock’s BUS Pumping when idling

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IRAUDAMP8 REV 1.0

Load Impedance

Each channel is optimized for a 4 Ω speaker load in half bridge.

Input Signal and Gain Setting

A proper input signal is an analog signal ranging from 20Hz to 20kHz with up to 3 VRMS 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, especially with greater than 8 Ω load impedances, and the LC

resonance can activate OCP.

The IRAUDAMP8 has an RC network called a Zobel network (R21 and C14) to damp the

resonance and prevent peaking frequency response with light loading impedance. (Fig 21)

Fig 21 Output Low Pass Filter and Zobel Network

Gain Setting

The ratio of resistors R4A~D/R1A~D in Fig 22 sets voltage gain. The IRAUDAMP8 has no on board volume

control. To change the voltage gain, change the input resistor term R1A~D. Changing R4A~D affects PWM

control loop design and may result poor audio performance.

www.irf.com Page 26 of 34

IRAUDAMP8 REV 1.0

R20B

22R

C4A

1nF,50V

C2A 2.2nF,50V

R2A 120R

R2B 120R

C3C

2.2nF,50V

C4C1nF,50V

C2D

2.2nF,50V

R7 10R

C6 4.7uF,10V

C7 4.7uF,10V

C2C

2.2nF,50V

R6 10R

R20A

22R

R9A

22R

R9B

22R

R9C

22R

R9D

22R

R20D

22R

R20C

22R

R21B

10R,1W

R21A

10R,1W

C13B

0.47uF, 400V

C13A

0.47uF, 400V

C13D0.47uF, 400V

C13C

0.47uF, 400V

C14B

0.1uF, 63V

C14A

0.1uF, 63V

CH3 OUTPUT

CH4 OUTPUT

CH2 OUTPUT

CH1 OUTPUT

R15C

10K R16C

3.9K

R17C

10K

R15D

10K

R16D

3.9K

R17D 10K

D1D 1N4148

D1C

1N4148

D2C1N4148 R18C

4.7R

R14B

4.7R

C9B

10uF,16V

R16A

3.9K

D1A 1N4148

R15A

10K

R17A 10K

D2B

1N4148 R18B

4.7R

R17B

10K

D1B

1N4148

R16B

3.9K

R15B 10K

R14A 4.7R

C9A

10uF,16V

R13 1K

R12 NC

R11 8.2K R10 2.2K

R4B

100K 1%

R4A

100K 1%

R2C

120R

R3C 4.7K

R1C 22K

R2D

120R

R1D 22K

R4C

100K 1%

R4D

100K 1%

C4D 1nF,50V

C3D

2.2nF,50V

R3A 4.7K

R1B 22K

R3B 4.7K

R1A 22K

C1A 100pF, 50V

R3D 4.7K

C3A 2.2nF,50V

C2B 2.2nF,50V C3B 2.2nF,50V

C4B

1nF,50V D2A 1N4148

R18A

4.7R

D2D

1N4148

R18D

4.7R

R21D

10R,1W

R21C

10R,1W

C14D

0.1uF, 63V

C14C

0.1uF, 63V

NC

3

NC

2

NC

1

CSD

48

GND

41

IN4

40

COMP4

39

IN3

38

VAA

43

NC

5

VS4 27

CSH4 30

NC 31

COMP2

45 LO2 16

VCC2 17

CSH3 23

VS3 26

VB2

8

HO4 28

VCC 33

COMP1

47

LO3 22

VREF 36

OCSET 35

LO1 15

LO4 21

VB3 24

HO3 25

COM2 20

NC 18

NC

6

COM 32

HO2

9

VS2

10

NC

4

VS1

11

HO1

12

VB1 13

CSH1 14

VB4 29

DT 34

IN2

44

IN1

46

CSH2

7

NC 19

COMP3

37

VSS

42

-B 0

IC1

MLQP48_4CH

C19A

0.1uF,100V

R19A

1R

R19D

1R

L1

22uH

L2

22uH

C19B

0.1uF,100V

R19B

1R

C19C

0.1uF,100V

R19C

1R

R22

10R

D3

1N4148

R22D

10K

R22C 10K

R22B 10K

Q1A

IRF6665

Q2A

IRF6665

Q1B

IRF6665

Q2B

IRF6665

Q2D

IRF6665

Q1C

IRF6665

Q2C

IRF6665

Q1D

IRF6665

C1B 100pF, 50V

C1C 100pF, 50V

C1D 100pF, 50V

GND

CSD

GND

D4

1N4148

C5A 10uF, 16V

C5B 10uF, 16V

C5C 10uF, 16V

C5D 10uF, 16V

R24B 2.2K

R24A 2.2K

R24D 2.2K

R24C 2.2K

R3

22k

C1

0.1uF,50V

VR1

10K

C40

N/A

C41

N/A

HT 1

OS

5

VT 3

GND 2

VCC

4

IC6

LM26CIM5-XHA

R51

22k

D51

4.7V

R52

15k

C10C

22uF, 16V

C10B

22uF, 16V

C10A

22uF, 16V

C10D

22uF, 16V

C8

10uF, 16V

VCC

1OUT 5

SET

3GND

2

DIT 4

IC2

LTC1799

R43

510R,1W

R44

510R,1W

C17B

1000uF,35V

C17A

1000uF,35V

C17C

0.1uF,50V

C17D

0.1uF,50V

R23B

100k

R23A

100k

1A

1

1B

2

2Y

3

GND

42A 5

2B 6

1Y 7

VCC 8

IC8

TC7W00FFCT-ND

L5 220uH

C32

2.2uF, 50V

C37

22uF, 16V

C33

0.1uF, 50V

C34

0.01uF, 25V

C35

2200pF,50V

C36

0.01uF, 50V

R39

100k

R40

100k

R42

3.3k

R32

1k

R41

120k

D7

R31

5.1k

DS1

Q1

FX491

Q2

MMBT5401

R38

10R

R37

47k

Z1

24V

Z2

15V

R36

5.1k

SW

1

BST

2

RCL

3

RTN

4

VIN 8

VCC 7

RON/SD 6

FB 5

IC9

LM5007

Q5

MMBT5551

R59

22k

Q3

MMBT5551

Q4

MMBT5551

R54

10k

R55

47k

R53

10k

R57

47k

R50

47k

R58

47k

Z3

39V

Z4

18V

OVP UVP

+B

GND

-B

R46

33k

1

2

3

4

5

6

7

8

CN1

CH1

GND

CH2

GND

CH3

GND

CH4

CH4 INPUT

CH3 INPUT

CH2 INPUT

CH1 INPUT

1

2

3

4

P2

1

2

3

4

P3

1

2

3

P1

+B

GND

-B

CH2 OUTPUT

CH1 OUTPUT

GND

CH3 OUTPUT

CH4 OUTPUT

GND

-5v

+5v

VCC

C12A 220pF

VSS

VAA -B

R22A

10K

C19D

0.1uF,100V

SD

R56

47k

CH2

CH1

R60

15k

C12B 220pF

C12C 220pF

C12D 220pF

Q8 ZX5T853

Q9

ZX5T953

R45

33k

Z5

5.6V

Z6

5.6V

R4 0R0 or N/A

R1

0R0 or N/A

GND GND

C61

0.01uF, 50V

R61 10k

R62 10k

For EMI

C62

0.01uF, 50V

R12A 47K

R12B 47K

R12C 47K

R12D 47K

Fig 22 IRAUDAMP8 Schematic

Schematic

www.irf.com Page 27 of 34

IRAUDAMP8 REV 1.0

IRAUDAMP8 Fabrication Materials

Table 1 IRAUDAMP8 Electrical Bill of Materials

Quantity Value Description Designator Part Number Vender

1 0.1uF,50V

CAP CER .1UF 50V 10% X7R

0603 C1 490-1519-1-ND

Murata Electronics

North America

4 100pF, 50V

CAP CERAMIC 100PF 50V

NP0 0603 C1A, C1B, C1C, C1D 399-1061-1-ND Kemet

9 2.2nF,50V

CAP CER 2200PF 50V 10%

X7R 0603

C2A, C2B, C2C, C2D,

C3A, C3B, C3C, C3D,

C35 490-1500-1-ND Murata Electronics

North America

4 1nF,50V CAP 1000PF 50V

CERAMICX7R 0603 C4A, C4B, C4C, C4D 399-1082-1-ND Kemet

4 10uF, 16V

CAP 10UF 16V HA ELECT

SMD C5A, C5B, C5C, C5D PCE4179CT-ND Panasonic - ECG

2 4.7uF,10V

CAP CERM 4.7UF 10V Y5V

0805 C6, C7 478-1429-1-ND AVX Corporation

1 10uF, 16V CAP CER 10UF 16V Y5V 1206 C8 490-3383-1-ND Murata Electronics

North America

2 10uF,16V CAP CER 10UF 16V Y5V 0805 C9A, C9B 490-3347-1-ND Murata Electronics

North America

5 22uF, 16V CAP CER 22UF 16V X7R 1210 C10A, C10B, C10C,

C10D, C37 445-3945-1-ND TDK Corporation

4 220pF CAP CER 220PF 50V 10%

X7R 0603 C12A, C12B, C12C,

C12D 490-1483-1-ND Murata Electronics

North America

4 0.47uF, 400V

CAP .47UF 400V METAL

POLYPRO C13A, C13B, C13C,

C13D 495-1315-ND EPCOS Inc

4 0.1uF, 63V

CAP FILM MKP .1UF 63VDC

2% C14A, C14B, C14C,

C14D BC2054-ND Vishay/BC

Components

2 1000uF,35V

CAP 1000UF 35V ELECT

SMG RAD C17A, C17B 565-1086-ND United Chemi-Con

2 0.1uF,50V

CAP .10UF 50V CERAMIC

X7R 1206 C17C, C17D 399-1249-1-ND Kemet

4 0.1uF,100V

CAP CER .10UF 100V X7R

10% 0805 C19A, C19B, C19C,

C19D 445-1418-1-ND TDK Corporation

1 2.2uF, 50V

CAP CER 2.2UF 50V X7R

1206 C32 490-3367-1-ND

Murata Electronics

North America

1 0.1uF, 50V

CAP CER .1UF 50V 10% X7R

0805 C33 490-1666-1-ND

Murata Electronics

North America

1 0.01uF, 25V

CAP 10000PF 25V CERM X7R

0603 C34 PCC1763CT-ND Panasonic - E CG

1 0.01uF, 50V

CAP CER 10000PF 50V 20%

X7R 0603 C36 490-1511-1-ND

Murata Electronics

North America

2 0.01uF, 50V

CAP 10000PF 50V CERAMIC

X7R 0603 C61, C62 399-1091-1-ND Kemet

1 ED1520-ND

TERMINAL BLOCK 3.5MM

8POS PCB CN1 ED1520-ND

On Shore Technology

Inc

10 1N4148 DIODE SWITCH 100V

400MW SOD-123

D1A, D1B, D1C, D1D,

D2A, D2B, D2C, D2D,

D3, D4 1N4148W-FDICT-ND Diodes Inc

1 DIODE1 DIODE SCHOTTKY 100V

1.5A SMA D7 10MQ100NPBFCT-ND Vishay/Semiconductors

1 4.7V DIODE ZENER 500MW 4.7V

SOD123 D51 MMSZ4V7T1GOSCT-ND ON Semiconductor

1 Blue LED

LED BLUE CLEAR THIN

0805 SMD DS1 160-1645-1-ND Lite-On Inc

1 MLQP48_4CH 4ch Audio Class D Controller IC1 IR2093MPBF International Rectifier

1 LTC1799

IC OSCILLATOR RES SET

TSOT23-5 IC2 LTC1799CS5#TRMPBFCT-

ND Linear Technology

1 LM26CIM5-

XHA IC THERMOSTAT PRESET

SOT23-5 IC6 LM26CIM5-XHACT-ND

National

Semiconductor

1 TC7W00FFCT-

ND IC GATE NAND DUAL

2INPUT 8-SOP IC8 TC7W00FFCT-ND Toshiba

1 LM5007 IC REG SW STEP-DOWN 80V

8-LLP IC9 LM5007SDCT-ND

National

Semiconductor

www.irf.com Page 28 of 34

IRAUDAMP8 REV 1.0

2 22uH Fixed inductors for Digital

Audio Amplifier L1, L2 DAEPW-M185X TOKO

1 220uH POWER INDUCTOR 220UH

0.49A SMD L5 308-1538-1-ND Sumida Corporation

1 Header 3

CONN TERM BLOCK PCB

5.0MM 3POS P1 281-1415-ND Weidmuller

2 SP OUT TERMINAL BLOCK 3.5MM

4POS PCB P2, P3 ED1516-ND On Shore Technology

Inc

1 FX491 TRANS HP NPN 60V 1000MA

SOT-23 Q1 FMMT491CT-ND Zetex Inc

8 IRF6665 MOSFET N-CH 100V 4.2A

DIRECTFET Q1A, Q1B, Q1C, Q1D,

Q2A, Q2B, Q2C, Q2D IRF6665TRPBFCT-ND International Rectifier

1 MMBT5401

TRANS 150V 350MW PNP

SMD SOT-23 Q2 MMBT5401-FDICT-ND Diodes Inc

3 MMBT5551

TRANS NPN 160V 350MW

SMD SOT-23 Q3, Q4, Q5 MMBT5551-FDICT-ND Diodes Inc

1 ZX5T853

TRANSISTOR 4.5A 100V

SOT-89 Q8 ZX5T853ZCT-ND Zetex Inc

1 ZX5T953

TRANSISTOR PNP 3.5A 100V

SOT-89 Q9 ZX5T953ZCT-ND Zetex Inc

1 0R0 RES ZERO OHM 1/10W 5%

0603 SMD R1 P0.0GCT-ND Panasonic - ECG

7 22K RES 22K OHM 1/10W 5%

0603 SMD R1A, R1B, R1C, R1D,

R3, R51, R59 RHM22KGCT-ND Rohm

4 120R RES 120 OHM 1/10W 5% 0603

SMD R2A, R2B, R2C, R2D RHM120GCT-ND Rohm

4 4.7K RES 4.7K OHM 1/10W 5%

0603 SMD R3A, R3B, R3C, R3D RHM4.7KGCT-ND Rohm

4 100K 1%

RES 100K OHM 1/8W 1%

0805 SMD R4A, R4B, R4C, R4D RHM100KCRCT-ND Rohm

4 10R RES 10 OHM 1/10W 5% 0603

SMD R6, R7, R22, R38 RHM10GCT-ND Rohm

8 22R RES 22 OHM 1/10W 5% 0603

SMD

R9A, R9B, R9C, R9D,

R20A, R20B, R20C,

R20D RHM22GCT-ND Rohm

1 2.2K RES 2.2K OHM 1/10W 5%

0603 SMD R10 RHM2.2KGCT-ND Rohm

1 8.2K RES 8.2K OHM 1/10W 5%

0603 SMD R11 RHM8.2KGCT-ND Rohm

2 1K RES 1.0K OHM 1/10W 5%

0603 SMD R13, R32 RHM1.0KGCT-ND Rohm

6 4.7R RES 4.7 OHM 1/10W 5% 0603

SMD R14A, R14B, R18A,

R18B, R18C, R18D RHM4.7GCT-ND Rohm

16

10K RES 10K OHM 1/10W 5%

0603 SMD'

R15A, R15B, R15C,

R15D, R17A, R17B,

R17C, R17D, R22A,

R22B, R22C, R22D,

R53, R54, R61, R62

RHM10KGCT-ND Rohm

4 3.9K RES 3.9K OHM 1/10W 5%

0603 SMD R16A, R16B, R16C,

R16D RHM3.9KGCT-ND Rohm

4 1R RES 1.0 OHM 1/8W 5% 0805

SMD R19A, R19B, R19C,

R19D RHM1.0ARCT-ND Rohm

4 10R,1W RES 10 OHM 1W 1% 2512

SMD R21A, R21B, R21C,

R21D PT10AECT-ND Panasonic - ECG

4 100k RES 100K OHM 1/10W 5%

0603 SMD R23A, R23B, R39, R40 RHM100KGCT-ND Rohm

4 2.2K RES 2.2K OHM 1/8W 5% 0805

SMD R24A, R24B, R24C,

R24D RHM2.2KARCT-ND Rohm

1 5.1k RES 5.1K OHM 1/8W 5% 0805

SMD R31 RHM5.1KARCT-ND Rohm

1 5.1k RES 5.1K OHM 1/10W 5%

0603 SMD R36 RHM5.1KGCT-ND Rohm

6 47k RES 47K OHM 1/10W 5%

0603 SMD R37, R50, R55, R56,

R57, R58 RHM47KGCT-ND Rohm

1 120k RES 120K OHM 1/10W 5%

0603 SMD R41 RHM120KGCT-ND Rohm

1 3.3k RES 3.3K OHM 1/10W 5%

0603 SMD R42 RHM3.3KGCT-ND Rohm

www.irf.com Page 29 of 34

IRAUDAMP8 REV 1.0

2 510R,1W

RES 510 OHM 1W 5% 2512

SMD R43, R44 PT510XCT-ND Panasonic - ECG

2 33k RES 33K OHM 1/10W 5%

0603 SMD R45, R46 RHM33KGCT-ND Rohm

2 15k RES 15K OHM 1/10W 5%

0603 SMD R52, R60 RHM15KGCT-ND Rohm

1 10K POT 10K OHM 3MM CERM

SQ TOP SMD VR1 ST32ETB103CT-ND Copal Electronics Inc

1 24V DIODE ZENER 500MW 24V

SOD123 Z1 BZT52C24-FDICT-ND Diodes Inc

1 15V DIODE ZENER 500MW 15V

SOD123 Z2 BZT52C15-FDICT-ND Diodes Inc

1 39V DIODE ZENER 39V 500MW

SOD-123 Z3 BZT52C39-FDICT-ND Diodes Inc

1 18V DIODE ZENER 500MW 18V

SOD123 Z4 BZT52C18-FDICT-ND Diodes Inc

2 5.6V DIODE ZENER 500MW 5.6V

SOD123 Z5, Z6 MMSZ5V6T1GOSCT-ND ON Semiconductor

Table 2 IRAUDAMP8 Mechanical Bill of Materials

Quantity Value Description Designator Digikey

P/N Vendor

7 Washer #4 SS WASHER LOCK

INTERNAL #4 SS

Lock washer 1, Lock washer 2,

Lock washer 3, Lock washer 4,

Lock washer 5, Lock washer 6

Lock washer 7

H729-

ND

Building

Fasteners

1 PCB

Print Circuit Board

IRAUDAM8M_Rev

3.0 .PCB

PCB 1 Custom

7 Screw 4-

40X5/16

SCREW MACHINE

PHILLIPS 4-40X5/16

Screw 1, Screw 2, Screw 3,

Screw 4, Screw 5, Screw 6,

Screw 7,

H343-

ND

Building

Fasteners

4 Stand off 0.5" STANDOFF HEX 4-

40THR .500"L ALUM

Stand Off 1, Stand Off 2, Stand

Off 3, Stand Off 4

1893K-

ND

Keystone

Electro-

nics

1/16 AAVID 4880G

THERMAL PAD .080" 4X4"

GAPPAD thermal pad under heatsink BER164-

ND

Therm-

alloy

www.irf.com Page 30 of 34

IRAUDAMP8 REV 1.0

IRAUDAMP8 Hardware

4.5 4.5

33

10827 27

12 14

1.6

6

10.5

16

6

12

IRAUDAMP8 Heat Spreader

All thread holes are 4-40 X 8mm dip ,minimum

Note:

All dimensions are in millimeters

Tolerances are ±0.1mm

Material:ALUMINUM

Fig 23 Heat Spreader

.

Fig 24 Hardware Assemblies

Screw

H343-ND

Screws

H343-ND

Stand Off 3

1893K-ND

Screw

Stand Off 4

1893K-ND

Lock washers

H729-ND

Lock washer

Stand Off 1

1893K-ND

Stand Off 2

1893K-ND

Lock washer

Screw

H343-ND

Lock washer

Screw

H343-ND

Lock washer

Screw

H343-ND

Lock washer

Screw

Thermal Pad

Th l d

www.irf.com Page 31 of 34

IRAUDAMP8 REV 1.0

IRAUDAMP8 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 32 of 34

IRAUDAMP8 REV 1.0

Fig 25 IRAUDAMP8 PCB Top Overlay (Top View)

www.irf.com Page 33 of 34

IRAUDAMP8 REV 1.0

Fig 26 IRAUDAMP8 PCB Bottom Layer (Top View)

www.irf.com Page 34 of 34

IRAUDAMP8 REV 1.0

Revision changes descriptions

Revision Changes description Date

Rev 1.0 Released Jan, 08th 2009

Rev 1.1 ROHS Compliant (BOM Updated) May,29th 2009

WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105

Data and specifications subject to change without notice. 01/29/2009