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

RREEFFEERREENNCCEE DDEESSIIGGNN IRDCiP2021C-1

IRDCiP2021C-1: 500kHz, 40A, Single Output, Dual Phase Synchronous Buck Converter Featuring iP2021C and IR3623M

Overview This reference design is capable of delivering a continuous current of 40A, single output without heatsink at an ambient temperature of 45ºC and airflow of 200LFM. Fig. 4 – Fig. 16 provide performance graphs, thermal images, and waveforms. Fig. 1 – Fig. 3 are provided to engineers as design references for implementing an IR3623+iP2021C solution.

The components installed on this demoboard were selected based on operation at an input voltage of 12V (+/-10%), a switching frequency of 500kHz (+/-15%), and an output voltage of 1.2V. Major changes from these set points may require optimizing the control loop and/or adjusting the values of input/output filters in order to meet the user’s specific application requirements. Refer to iP2021C and IR3623 datasheets for more information.

IRDCiP2021C-1 Recommended Operating Conditions (refer to the iP2021C datasheet for maximum operating conditions)

Input voltage: 8.5V – 14.5V

Output voltage: 0.8 – 5V

Switching Freq: 500kHz

Output current: This reference design is capable of delivering a continuous current of 40A without heatsink at an ambient temperature of 45ºC and airflow of 200LFM.

Demoboard Quick Start Guide Initial Settings: VOUT is set to 1.2V, but can be adjusted from 0.8V to 5V by changing the values of R11 and R15 according to the following formula:

R11 = R15 = (10k * 0.8) / (VOUT - 0.8)

The switching frequency is set to 500kHz, but can be adjusted by changing the value of R26. See Fig. 4 for the relationship between R26 and the switching frequency.

8/13/2009

IRDCiP2021C-1 Power Up Procedure: 1. Apply input voltage across VIN and PGND.

2. Apply load across VOUT pads and PGND pads.

3. Toggle the SEQ (SW1) and EN (SW2) switches to the ON position.

4. Adjust load to desired level. See recommendations above.

www.irf.com 2

IRDCiP2021C-1

3 www.irf.com

Demoboard Schematic

Fig. 1 Schematic

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34

56

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C2

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16V

C5

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16V

C6

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16V

C3

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16V

C7

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R10

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R16

0

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open

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(500

kHz)

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C42

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C33

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C25

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R38 0 R48

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R49 0

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VOS1

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D-

VOS1

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59.0K

(600

kHz)

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3623

M

www.irf.com 4

IRDCiP2021C-1

Demoboard Component Placement

Fig. 2 Top Layer (Face View)

Fig. 3 Bottom Layer (Through View)

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IRDCiP2021C-1 Description of Test Points and Connectors

1. Jumpers

Jumper Pin Name Description

SW1 EN Board Enable ( switch Up = On ) - Vin pin on top Off, Down =

SW2 SEQ Sequence ( switch Up = Off, Down = On ) - Vin pin on top

2. Points ctors Test /Conne

Test Point Pin Name Description

T1 / T2 VIN / P Vin supply voltage GND

T ense P2 / TP28 VIN / PGND Vin supply voltage s

T3 / T5 / T7 VOUT1 / PGND / PGND to DC load Channel 1 Output, connect

TP35 / TP33 VOUT1 / PGND Channel 1 Output sense

TP21 / TP37 VSW1 / PGND Channel 1 switch node / PGND test points

TP9 EN1 Channel 1 Enable test point

TP11 PWM1 Channel 1 PWM test point

TP19 CC1 Channel 1 error amplifier output

TP25 FB1 Channel 1 error amplifier non-inverting input

T4 T2 / PGND / PGND / T6 / T9 VOU Channel 2 Output, connect to DC load

TP36 / TP34 VOUT2 / PGND Channel 2 Output sense

TP22 / TP38 VSW2 / PGND Channel 2 switch node / PGND test points

TP10 EN2 Channel 2 Enable test point

TP12 PWM2 Channel 2 PWM test point

TP20 CC2 Channel 2 error amplifier output

TP26 FB2 Channel 2 error amplifier non-inverting input

TP7 / TP8 / PGND le VDD Supply voltage for IRU3623 and iPOWIR modu

TP23 SYNC External frequency synchronization input

TP17 TRACK1 if not used Channel 1 tracking input, pull-up to Vout3

TP18 TRACK2 Track2 test point

TP15 PGOOD1 Channel 1 Power good test point

TP16 PGOOD2 Channel 2 Power good test point

TP13 SS1 Channel 1 Soft start test point

TP14 SS2 Channel 2 Soft start test point

TP24 FAULT Fault monitor test point

3. points ement Test for Efficiency Measur

Test Point Pin Name Description

TP1 / TP4 +VINS 1 Channel 1 Vin sense for eff rement 1 / -VOUTS iciency measu

TP3 / TP4 +VOUTS1 / -VOUTS1 nt Channel 1 Output sense for efficiency measureme

TP27 / TP6 +VINS2 / -VOUTS2 Channel 2 Vin sense for efficiency measurement

TP5 / TP6 +VOUTS2 / -VOUTS2 nt Channel 2 Output sense for efficiency measureme

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IRDCiP2021C-1

Test Results

Fig. 4 Relationship Between Switching Frequency and R2

6

Fig. 5 Power Up Sequence (C3: EN, C1: SS1, C4: VOUT)

Fig. 6 Power Down Sequence (C3: EN, C1: SS1, C4: VOUT)

VIN = 12V, VOUT = 1.2V, Iout = 40A, fsw = 500 kHz

VIN = 12V, VOUT = 1.2V, Iout = 40A, fsw = 500 kHz

7 www.irf.com

IRDCiP2021C-1

g. 7 Hiccup Mode Over Current Protection (C1: SS1, C4: Iout, C3: VOUT)

VIN = 12V, VOUT = 1.2V, fsw = 500 kHz

Fi

Fi

g. 8 Hiccup Mode Over Current Protection (C1: SS1, C4: Iout, C3: VOUT)

VIN = 12V, VOUT = 1.2V, fsw = 500 kHz

Fig. 9 Deadtime and Ringing on Switch Node

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IRDCiP2021C-1

Fig. 2)

Fig. 10 Output Voltage DC Ripple

Vp-p = 20 mV

out sw

Fig. 11 Output Voltage DC Ripple

12 Load Transient Response (C1: VOUT – AC, C2: Iout divided by

VIN = 12V, VOUT = 1.2V, I = 20A, f = 500 kHz

VIN = 12V, VOUT = 1.2V, Iout = 20A, fsw = 500 kHz

VIN = 12V, VOUT = 1.2V, Iout = 0-40A, 0.5A/µs, Hfsw = 500 k z

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IRDCiP2021C-1

Fig. 13 Bode Plot (VIN = 12V, VOUT = 1.2V, Iout = 20A) Current Sharing Accuracy The accuracy of current sharing is tested by measuring the DC voltage across the two inductors at the following operating conditions: VIN = 12V; VOUT = 1.2V; Iout = 10 – 40A. The test results are shown below:

Table 1 Inductor DC Voltages at Different Currents for Single Output Configuration

Iout (A) VL1 (mV) VL2 (mV)

fc = 65 kHz PM = 49

10 1.5 1.9 20 3.4 3.8 30 5.5 5.8 40 7.5 7.9

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IRDCiP2021C-1

VIN = 12V, VOUT = 1.2V, 200LFM, fsw = 500kHz, No Heatsink

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0 5 10 15 20 25 30 35 40

Load Current (A)

Po

wer

Lo

ss (

W)

45CRoom Temperature

Fig. 14 Power Loss

VIN = 12V, VOUT = 1.2V, 200LFM, fsw = 500kHz, No Heatsink

72%

74%

76%

78%

80%

82%

84%

86%

88%

90%

92%

0 5 10 15 20 25 30 35 40

Load Current (A)

Eff

icie

ncy

45C

Room Temperature

Fig. 15 Efficiency

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IRDCiP2021C-1

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IRDCiP2021C-1

www.irf.com 12

Fig. 16 Thermal Image: Iout = 40A, VIN = 12V, VOUT = 1.2V, TA = 45oC, fsw = 500kHz, 200LFM, No Heatsink, Maximum IC Temperature = 94.2oC

Refer to the following application notes for detailed guidelines and suggestions when implementing iPOWIR Technology products: AN-1043: Stabilize the Buck Converter with Transconductance Amplifier This paper explains how to design the voltage compensation network for Buck Converters with Transconductance Amplifier. The design methods and equations for Type II and Type III compensation are given. 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 include 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. Internation l Rectifier cannot guarantee suitability for your applications, and is not liable for any result of usage for such applications including, without limitation, erty 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

a

personal or prop