LM5025AEVAL National Semiconductor, LM5025AEVAL Datasheet

LM5025AEVAL

Manufacturer Part Number

LM5025AEVAL

Description

BOARD EVALUATION LM5025A

Manufacturer

National Semiconductor

Series

PowerWise®r

Datasheets

1.LM5025ASDNOPB.pdf (16 pages)

2.LM5025EVAL.pdf (14 pages)

3.LM5115EVAL.pdf (16 pages)

Specifications of LM5025AEVAL

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

3.3V

Current - Output

30A

Voltage - Input

36 ~ 72V

Regulator Topology

Buck

Frequency - Switching

230kHz

Board Type

Fully Populated

Utilized Ic / Part

LM5025A

Lead Free Status / RoHS Status

Not applicable / Not applicable

Power - Output

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LM5115/5025A Evaluation

Board

Introduction

The LM5115/LM5025A evaluation board provides the design

engineer with a secondary side post regulated (SSPR) out-

put from an existing Active Clamp Forward topology. Infor-

mation on the LM5025A active clamp evaluation board can

be found in Application Note AN-1345. Note that other types

of isolated power converters (e.g. push-pull, half-bridge, and

full-bridge) can be used in the place of the LM5025A active

clamp forward converter to drive the LM5115 AC evaluation

board.

The evaluation board specifications are:

• Input voltage: 36V to 72V, 48V nominal on LM5025A

• Output voltage Main: 3.3V nominal

• Output current Main: 0 to 30A

• Current limit Main: )30A

• Output voltage Secondary: 2V

• Output current Secondary: 0 to 9A

• Current limit Secondary: )9A

• Measured efficiency on secondary only: 98% at 36V,

• Load regulation: 2mV change from 1A-7A, 36V

• Size: 2.0 x 1.125 x 0.375 in.

The printed circuit board consists of 4 layers of 2 oz copper

on FR4 material, with a thickness of 0.050 in. It is designed

for continuous operation at rated load with a minimum airflow

of 200 LFPM.

Iload = 1A, 93% at 48V, Iload = 4A

72V

FIGURE 1. LM5025A Evaluation Board Top Side

AN201403

Vin

National Semiconductor

Application Note 1368

Neil Gutierrez & Kim Nelson

April 2005

Theory of Operation

The LM5115 controller contains all of the features necessary

to implement multiple output power converters utilizing the

Secondary Side Post Regulation (SSPR) technique. The

SSPR technique develops a highly efficient and well regu-

lated auxiliary output from the secondary side switching

waveform of an isolated power converter.

Synchronization of the LM5115 comes from the main pulsed

signal of the transformer secondary winding. Resistor R2

and R4 sense the pulsing signal to form an internal synchro-

nization signal and an internal current to charge the RAMP of

the LM5115. The LM5115 controls the buck power stage with

leading edge pulse width modulation (PWM) to hold off the

high side driver until the necessary volt*seconds is estab-

lished for regulation. Representative waveforms are shown

in Figure 4.

Bias to the part comes from a rectified pulse signal. Note that

the pulse signals vary from 6Vpp to 12Vpp, with Vin varying

from 36V to 72V, respectively. Therefore, the Vcc regulator

will not regulate at 7V until the peak to peak voltage is

slightly higher than 7.5V (accounting for the diode drop to the

bias). The intention was to show that with non-regulation on

Vcc the LM5115 is still capable of providing the secondary

voltage of 2V from the main 3.3V. Adaptive deadtime control

delays the top and bottom drivers to avoid shoot through

currents (Figure 7 & 8).

20140301

www.national.com

Related parts for LM5025AEVAL

LM5025AEVAL Summary of contents

Page 1

... The printed circuit board consists of 4 layers copper on FR4 material, with a thickness of 0.050 in designed for continuous operation at rated load with a minimum airflow of 200 LFPM. FIGURE 1. LM5025A Evaluation Board Top Side © 2005 National Semiconductor Corporation National Semiconductor Application Note 1368 Neil Gutierrez & Kim Nelson April 2005 ...

Page 2

Theory of Operation www.national.com (Continued) FIGURE 2. LM5025A Evaluation Board Bottom Side FIGURE 3. LM5115 Evaluation Board 2 20140302 20140303 ...

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Board Layout and Probing Figures 1-3 show the board layout, main components, and critical probe points for testing the LM5115 AC mode evalu- ation board in conjunction with the LM5025A board. The following notes should be considered prior to applying ...

Page 4

FIGURE 4. Representative Waveform FIGURE 5. System Efficiency vs. Load Current and V FIGURE 6. Adjusted Efficiency on secondary side vs. Load Current and V www.national.com 20140304 20140305 IN 20140306 IN FIGURE 9. Secondary Output Short Response 4 20140307 FIGURE ...

Page 5

FIGURE 10. Secondary Step Load Response 20140311 FIGURE 11. Cross Regulation Step Load 20140312 FIGURE 12. Startup Response FIGURE 13. Shutdown Response FIGURE 14. Secondary Ripple Voltage FIGURE 15. Output vs. Load Current & 20140313 20140314 20140315 ...

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FIGURE 16. Secondary Closed Loop Response 6 20140316 ...

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7 www.national.com ...

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www.national.com 8 ...

Page 9

Bill of Materials ITEM PART NUMBER C 1 C3216X7R1E105K C 2 C2012X7R1H104K C 3 C3216X7R1E105K C 4 C2012COG1H331K C 5 C2012X7R1H104K C2012COG1H223K C 8 C2012COG1H471K C4532X7SOG686M C 12 C4532X7SOG686M C ...

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PCB Layout(s) www.national.com 20140319 FIGURE 19. Top Silk Screen LM5115 10 ...

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PCB Layout(s) (Continued) FIGURE 20. Top Layer LM5115 11 20140320 www.national.com ...

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PCB Layout(s) (Continued) www.national.com 20140321 FIGURE 21. Layer 2 LM5115 12 ...

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PCB Layout(s) (Continued) 20140322 FIGURE 22. Layer 3 LM5115 13 www.national.com ...

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PCB Layout(s) (Continued) FIGURE 23. Bottom Layer LM5115, as Viewed from Top www.national.com 20140323 14 ...

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PCB Layout(s) (Continued) FIGURE 24. Bottom Silk Screen LM5115 15 20140324 www.national.com ...

Page 16

... BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...

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