12/03/04

International Rectifier • 233 Kansas Street, El Segundo, CA 90245 USA

RREEFFEERREENNCCEE DDEESSIIGGNN IRDCiP2003A-C

IRDCiP2003A-C: 1MHz, 160A, Synchronous Buck Converter Using iP2003A

Overview This reference design is capable of delivering up to a current of 160A with the enclosed heatsink attached at an ambient temperature of 60ºC with 400LFM or an ambient temperature of 45ºC with 200LFM of airflow. Performance graphs and waveforms are provided in figures 1–9. The figures and table in pages 5 – 8 are provided as a reference design to enable engineers to very quickly and easily design a 4-phase converter. Refer to the data sheet for the controller listed in the bill of materials in order to optimize this design to your specific requirements. A variety of other controllers may also be used, but the design will require layout and control circuit modifications.

Demoboard Quick Start Guide Initial Settings: The output is set to 1.3V, but can be adjusted from 0.8V to 3.3V by changing the voltage divider values of R3 and R32 according to the following formula:

R3 = R32 = (24.9k x 0.8) / (VOUT - 0.8)

The switching frequency per phase is set to 1MHz with the frequency set resistor R4. This creates an effective output frequency of 4MHz. The graph in figure 11 shows the relationship between R4 and the switching frequency per phase. The frequency may be adjusted by changing R4 as indicated; however, extreme changes from the 1MHz set point may require redesigning the control loop and adjusting the values of input and output capacitors. Refer to the SOA graph in the iP2003A datasheet for maximum operating current at different conditions.

Procedure for Connecting and Powering Up Demoboard: 1. Apply input voltage across (+12V) across VIN and PGND. 2. Apply load across VOUT pads and PGND pads. 3. Adjust load to desired level. See recommendations below.

IRDCiP2003A-C Recommended Operating Conditions (refer to the iP2003A datasheet for maximum operating conditions) Input voltage: 5V - 12V1 Output voltage: 0.8 - 3.3V Switching Freq: 1MHz per phase, 4MHz effective output frequency. Output current: This reference design is capable of delivering up to 160A with the enclosed heatsink attached, at an

ambient temperature of 60ºC with 400LFM of airflow, or an ambient temperature of 45ºC with 200LFM of airflow.

1Note: If Vin = 5V, then connect Vin to test point TP3 and Terminal T1 and remove jumper J1. Refer to schematic for details. Additionally, the threshold of the POR circuit should be adjusted to allow the supply to sequence properly.

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0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

0 20 40 60 80 100 120 140 160Output Current (A)

Pow

er L

oss

(W)

70%

71%

72%

73%

74%

75%

76%

77%

78%

79%

80%

81%

82%

83%

84%

85%

86%

0 20 40 60 80 100 120 140 160Output Current (A)

Effic

ienc

y (%

)

Fig. 1: Power Loss vs. Current Fig. 2: Efficiency vs. Current

Fig. 3: Bode Plot

Fig. 4: Input Voltage Ripple Waveform Fig. 5: Output Voltage Ripple Waveform

VIN = 12V VOUT = 1.3V fSW = 1MHz TA = 25°C

VIN = 12V VOUT = 1.3V fSW = 1MHz TA = 25°C

VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 25°C

Ripple = 90mVp-p Ripple = 7.0mVp-p

Phase Margin = 61° Cross-Over Freq. = 106kHz

VIN = 12V, VOUT = 1.3V IOUT = 160A, fSW = 1MHz TA = 25°C

VIN = 12V, VOUT = 1.3V IOUT = 160A, fSW = 1MHz TA = 25°C

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98.0%

98.2%

98.4%

98.6%

98.8%

99.0%

99.2%

99.4%

99.6%

99.8%

100.0%

0 20 40 60 80 100 120 140 160

Output Current (A)

Out

put V

olta

ge A

ccur

acy

(%)

Fig. 6: Output Voltage Accuracy vs. Current

Fig. 7: Power Up Waveform Fig. 8: Power Down Waveform

Fig. 9: Short Circuit Condition Waveform

VIN = 12V VOUT = 1.3V fSW = 1MHz TA = 25°C

VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 25°C

VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 25°C

Ch. 1: VIN 2V/div

Ch. 2: VOUT 0.5V/div

Ch. 1: VIN 2V/div

Ch. 2: VOUT 0.5V/div

Ch. 1: VOUT 1V/div

Ch. 2: IOUT 50A/div

VIN = 12V VOUT = 1.3V fSW = 1MHz TA = 25°C

Shortcircuit at start-up

Hiccups until short circuit is removed

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Board Temperature @ 1mm from edge of module:

TPCB (U2): 83.4°C TPCB (U3): 82.7°C TPCB (U4): 82.3°C TPCB (U5): 79.2°C

Board Temperature @ 1mm from edge of module:

TPCB (U2): 88.9°C TPCB (U3): 87.5°C TPCB (U4): 87.3°C TPCB (U5): 85.1°C

Fig. 10: Thermal Images With Board and Heatsink Temperatures

*>120.0°C

*<21.3°C

40.0

60.0

80.0

100.0

120.0

*>120.0°C

*<21.3°C

40.0

60.0

80.0

100.0

120.0

VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 45°C

Airflow = 200LFM

Max 70.7°C

Max 78.5°C

VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 60°C

Airflow = 400LFM

Airflow direction

Airflow direction

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Adjusting the Over-Current Limit R5, R7, R8, and R9 are the resistors used to adjust the over-current trip point. The trip point is a function of the controller and corresponds to the per phase output current indicated on the x-axis of Fig. 11. For example, selecting 3.65k resistors will set the trip point of each phase to 66A. (Note: Fig. 11 is based on iP2003A, TJ = 125°C. The trip point will be higher than expected if the reference board is cool and is being used for short circuit testing.)

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

3.5

3.6

3.7

43 45 47 49 51 53 55 57 59 61 63 65 67

Over-Current Trip Point (per Phase)

RIS

EN (k

Ω)

Fig. 11: RISEN vs. Current (per Phase)

10

100

100 1000

Output Frequency (kHz) (per Phase)

R4

(kΩ

)

Fig. 12: R4 vs. Frequency (per Phase)

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Fig. 13: Component Placement Top Layer

Heatsink Notes:

1) Always use the supplied Berquist Gap PadTM A3000 thermal interface material with heatsink. 2) Torque 5 x #2-56 machine screws to 15 +/-1 in-oz. 3) The heatsink is optimized for 400 LFM with unconfined airflow. Performance will improve with more airflow or confined

airflow. 4) Airflow direction should be parallel to fins for maximum performance.

Fig. 14: Heatsink Specification

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Fig. 15: Reference Design Schematic

R6 499

1%

C1

560p

F

R1 20k 1

%

R224

.9k 1%

R340

.2k 1%

R4 20k 1

%

C2

10uF

C

15

100uF

C16

100uF

L1

0.3uH

L2

0.3uH

R53.6

5k 1% R7

3.65k

1%

+5V

C3

10uF

C4

10uF

ENA

VSW

1

VSW

2

C5

10uF

TP6

VSW

1

TP7

VSW

2

L3 0.3uH

VSW

3TP

8VS

W3

L4 0.3uH

VSW

4TP

9VS

W4

R93.6

5k 1%R8

3.65k

1%

VOUT

Vin

R10

0 R12 0

R13

0

R11

0

T6 PG

ND

T7 PGND

T8 PGND

TP5

PGOO

D

T5 VOUT

T4 VOUT

T3 VOUT

T1 VIN

TP21

VOUT

S

TP22

PGND

S

VOUT

S

R16

10k 1

%

R17

10k 1

%

R18

10k 1

%

C33

10uF

R19

10k 1

%

VOUT

S

PGND

S

VSEN

6

COMP3

PWM

416

PGOO

D2

ISEN

415

VCC

1

ISEN

114

DROOP4

PWM

113

FB5

PWM

212

FS/E

N7

ISEN

211

GND

8

ISEN

310

PWM

39

U1 ISL6

558C

B

R22

open

+5V

ENA

R24

open

+5V

ENA

R26

open

+5V

ENA

R28

open

R29

openR30

open

+5V

+5V

+5V

C25

15pF

C26

220p

F

Vin

+5V

C34

0.1uF

R31

24.9k

1% R32

40.2k

1%

PRDY

1

PRDY

2

PRDY

3

PRDY

4

C37

0.22u

F

23

1

D1 CMPD

3003

APR

DY3

C38

0.22u

F

PRDY

4

C35

0.22u

F PRDY

1

C36

0.22u

F

PRDY

2

C41

330u

FC

4033

0uF

C39

330u

FT2 PG

ND

23

1

D2 CMPD

3003

A

TP13

VINS

TP17

PGND

S

C42

100uF

C46

10uF

C47

open

R36

open

R35

0

C27

10uF

C28

10uF

Outp

ut2

Adj/Gnd 1

Inpu

t3

U6 LM11

17DT

X-5.0

TP2 A

TP1 B

C64

open

C17

100uF

C18

100uF

C43

100uF

C65

open

C19

100uF

C20

100uF

C44

100uF

C66

open

C21

100uF

C22

100uF

C45

100uF

C67

open

C56

open

C57

open

C48

2.2uF

C49

2.2uF

C6

10uF

C7

10uF

C8

10uF

Vin

C30

10uF

C58

open

C59

open

C50

2.2uF

C51

2.2uF

C9

10uF

C10

10uF

C11

10uF

Vin

C31

10uF

C60

open

C61

open

C52

2.2uF

C53

2.2uF

C12

10uF

C13

10uF

C14

10uF

Vin

C32

10uF

C62

open

C63

open

C54

2.2uF

C55

2.2uF

+5V

+5V

+5V

+5V

21

3D3 LM

431

R38

26.1k

1%

R39

11k 1

%

R37

110k

1%

R41

1k 1%

R40

301

Vin

+5V

ENA

ENA

TP4

PGND

TP3

+5V

J1 Jump

er

VDD

1

ENAB

LE2

PWM

3

PRDY

4

VIN

8

VSW

6

PGND

7PG

ND5

VSWS1 9

VSWS2 10

U2

IP20

03A

VDD

1

ENAB

LE2

PWM

3

PRDY

4

VIN

8

VSW

6

PGND

7PG

ND5

VSWS1 9

VSWS2 10

U3

IP20

03A

VDD

1

ENAB

LE2

PWM

3

PRDY

4

VIN

8

VSW

6

PGND

7PG

ND5

VSWS1 9

VSWS2 10

U4

IP20

03A

VDD

1

ENAB

LE2

PWM

3

PRDY

4

VIN

8

VSW

6

PGND

7PG

ND5

VSWS1 9

VSWS2 10

U5

IP20

03A

2 3

1Q

1IR

LML6

402

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Table 1: Reference Design Bill of Materials

Refer to the following application notes for detailed guidelines and suggestions when implementing iPOWIR Technology products: AN-1028: Recommended Design, Integration and Rework Guidelines for International Rectifier’s iPowIR Technology BGA and LGA and Packages This paper discusses optimization of the layout design for mounting iPowIR BGA and LGA packages on printed circuit boards, accounting for thermal and electrical performance and assembly considerations. Topics discussed includes PCB layout placement, and via interconnect suggestions, as well as soldering, pick and place, reflow, inspection, cleaning and reworking recommendations. AN-1030: Applying iPOWIR Products in Your Thermal Environment This paper explains how to use the Power Loss and SOA curves in the data sheet to validate if the operating conditions and thermal environment are within the Safe Operating Area of the iPOWIR product. AN-1047: Graphical solution for two branch heatsinking Safe Operating Area Detailed explanation of the dual axis SOA graph and how it is derived. Use of this design for any application should be fully verified by the customer. International Rectifier cannot guarantee suitability for your applications, and is not liable for any result of usage for such applications including, without limitation, personal or property damage or violation of third party intellectual property rights. IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105

TAC Fax: (310) 252-7903