LM25005EVAL National Semiconductor, LM25005EVAL Datasheet

LM25005EVAL

Manufacturer Part Number

LM25005EVAL

Description

BOARD EVALUATION LM25005

Manufacturer

National Semiconductor

Datasheets

1.LM25005MHNOPB.pdf (22 pages)

2.LM25005EVAL.pdf (6 pages)

Specifications of LM25005EVAL

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

Current - Output

2.5A

Voltage - Input

7 ~ 42V

Regulator Topology

Buck

Frequency - Switching

300kHz

Board Type

Fully Populated

Utilized Ic / Part

LM25005

Lead Free Status / RoHS Status

Not applicable / Not applicable

Power - Output

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LM25005 Evaluation Board

Introduction

The LM25005 evaluation board is designed to provide the

design engineer with a fully functional power converter based

on Emulated Current Mode Control to evaluate the LM25005

regulator IC. The evaluation board provides a 5V output with

a 2.5A current capability. The ultra-wide input voltage ranges

from 7V to 42V. The design operates at 300kHz, a good com-

promise between conversion efficiency and solution size. The

printed circuit board consists of 2 layers of 2 ounce copper on

FR4 material with a thickness of 0.06 inches. This application

note contains the evaluation board schematic, Bill-of-Materi-

als (BOM) and a quick setup procedure. Refer to the LM25005

datasheet for complete circuit design information.

Evaluation Board Schematic

Powering and Loading

Considerations

Read this entire page prior to attempting to power the evalu-

ation board.

QUICK SETUP PROCEDURE

Step 1: Set the power supply current limit to 3.5A. Turn off

the power supply. Connect the power supply to the Vin ter-

minals.

Step 2: Connect the load, with a 2.5A capability, to the Vout

terminals. Positive connection to J2 and negative connection

to J3.

Step 3: The SD pin should be left open for normal operation.

Step 4: Set Vin to 24V with no load applied. Vout should be

in regulation with a nominal 5V output.

Step 5: Slowly increase the load while monitoring the output

voltage, Vout should remain in regulation with a nominal 5V

output as the load is increased up to 2.5 Amps.

Step 6: Slowly sweep the input voltage from 7 to 42V, Vout

should remain in regulation with a nominal 5V output.

300441

National Semiconductor

Application Note 1749

Robert Bell

November 7, 2007

The performance of the evaluation board is as follows:

Input Range: 7 to 42V

Output Voltage: 5V

Output Current: 0 to 2.5A

Frequency of Operation: 300 KHz

Board Size: 2.75 X 1 X 0.4 inches

Load Regulation: 1%

Line Regulation: 0.1%

Over Current Limiting

Step 7: Temporally short the SD pin to GND to check the

shutdown function.

Step 8: Increase the load beyond the normal range to check

current limiting. The output current should limit at approxi-

mately 3.8A. The power supply (Vin source) current limit may

need to be increased for this step. Cooling is critical during

this step.

AIR FLOW

Prolonged operation with high input voltage at full power will

cause the thermal shutdown circuit within the regulator IC to

activate. A stand-alone fan with at lease 200 LFM should al-

ways be provided.

POWERING UP

Using the shutdown pin provided will allow powering up the

source supply with the current level set low. It is suggested

that the load be kept low during the first power up. Set the

current limit of the source supply to provide about 1.5 times

the anticipated wattage of the load. As you remove the con-

nection from the shutdown pin to ground, immediately check

for 5 volts at the output.

www.national.com

30044101

Related parts for LM25005EVAL

LM25005EVAL Summary of contents

Page 1

... Vout should remain in regulation with a nominal 5V output as the load is increased up to 2.5 Amps. Step 6: Slowly sweep the input voltage from 7 to 42V, Vout should remain in regulation with a nominal 5V output. © 2007 National Semiconductor Corporation National Semiconductor Application Note 1749 Robert Bell ...

Page 2

A quick efficiency check is the best way to confirm that ev- erything is operating properly. If something is amiss you can be reasonably sure that it will affect the efficiency adversely. Few parameters can be incorrect in a switching ...

Page 3

... DIODE, 60V, CENTRAL DIODE, 100V, IR (D1-ALT) INDUCTOR, COOPER NOT USED NOT USED RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR REGULATOR, NATIONAL SEMICONDUCTOR 3 Value 2.2µ, 100V 2.2µ, 100V 330p, 100V 0.01µ, 100V 0.01µ, 100V 0.022µ, 100V 0.47µ, 16V 22µ ...

Page 4

PCB Layout www.national.com Component Side Solder Side Silkscreen 4 30044105 30044106 30044107 ...

Page 5

Notes 5 www.national.com ...

Page 6

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock Conditioners www.national.com/timing Data Converters www.national.com/adc Displays www.national.com/displays Ethernet www.national.com/ethernet Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www ...

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