LM27342MYEVAL National Semiconductor, LM27342MYEVAL Datasheet

LM27342MYEVAL

Manufacturer Part Number

LM27342MYEVAL

Description

Step-Down DC/DC Regulator Eval. Board

Manufacturer

National Semiconductor

Datasheet

1.LM27342MYEVAL.pdf (6 pages)

Specifications of LM27342MYEVAL

Silicon Manufacturer

National

Application Sub Type

Step Down Switching Regulator

Kit Application Type

Power Management - Voltage Regulator

Silicon Core Number

LM27342

Kit Contents

Board, Doc

Current page: 1 of 6
Download datasheet (508Kb)

LM27342 Demonstration

Board

Introduction

The LM27342 demonstration board is designed to provide the

power supply design engineer with a fully functional regulator

design which can be synchronized to an external clock be-

tween 1000 kHz and 2350 kHz. The evaluation board pro-

vides a 3.3V output with a 2A current capability. The wide

input voltage ranges from 5V to 20V. Without an external syn-

chronization signal, the design operates at 2000 kHz reducing

the solution size and keeping switching noise out of the AM

radio band. The printed circuit board consists of 4 layers of

copper on FR4 material. There is a ground plane on the in-

ternal layer directly beneath the LM27342, and a ground

plane on the bottom layer. The LM27342 is thermally tied to

the ground planes by thermal vias directly underneath the

Evaluation Board Schematic

Powering and Loading

Considerations

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

ation board.

QUICK START PROCEDURE

Step 1: Set the bench power supply current limit to 2A. Set

the power supply voltage to 12V. Turn off the power supply

output. Connect the power supply to the LM27342 demo

board. Positive connection to V

GND.

Step 2: Connect a load, as high as 2A, to the V

Positive connection to V

Step 3: Connect a signal generator to provide a synchroniza-

tion signal to the SYNC terminal. Positive connection to SYNC

and negative connection to GND.

Step 4: The EN pin should be left open for normal operation.

OUT

and negative connection to GND.

and negative connection to

300872

OUT

terminal.

National Semiconductor

Application Note 1929

Marc Davis-Marsh

November 20, 2008

device. The second internal layer is tied half to V

schematic, a quick setup procedure, and a Bill-of-Materials

(BOM). Refer to the LM27342 datasheet for complete circuit

design information.

The performance of the evaluation board is as follows:

Input Range: 5 to 20V

Output Voltage: 3.3V

Output Current: 0 to 2A

Frequency of Operation: 1000 kHz - 2350 kHz

Board Size: 1.1 X 1.3 inches

Step 5: Turn on the bench power supply with no load applied

to the LM27342. V

3.3V output.

Step 6: Slowly increase the load while monitoring the output

voltage, V

output as the load is increased up to 2 Amps.

Step 7: Slowly sweep the input voltage from 5 to 20V and

back to 12V, V

3.3V output.

Step 8: Turn on the signal generator, and synchronize the

LM27342 to a 3.3V square wave at 1 MHz. V

main in regulation with a nominal 3.3V output. Monitor SYNC

and SW to observe the synchronization behavior.

STARTING UP

The EN pin is tied to V

sistor allows the power supply design engineer to toggle EN

independently, if desired, and observe the start-up behavior

of the LM27342.

OUT

. This application note contains the evaluation board

OUT

should remain in regulation with a nominal 3.3V

OUT

should remain in regulation with a nominal

should be in regulation with a nominal

to simplify start-up. The pull-up re-

30087201

OUT

www.national.com

and half to

should re-

Related parts for LM27342MYEVAL

LM27342MYEVAL Summary of contents

Page 1

... Step 3: Connect a signal generator to provide a synchroniza- tion signal to the SYNC terminal. Positive connection to SYNC and negative connection to GND. Step 4: The EN pin should be left open for normal operation. © 2008 National Semiconductor Corporation National Semiconductor Application Note 1929 Marc Davis-Marsh November 20, 2008 device ...

Page 2

OVER CURRENT PROTECTION The evaluation board is configured with over-current protec- tion. The inductor current is limited to 4.0A (max). SYNCHRONIZATION A SYNC pin has been provided on the evaluation board. This pin can be used to synchronize the regulator ...

Page 3

... VOUT, EN, SYNC Test Point SW Miniature Test Point Bill of Materials Part Number LM27342 TMK325B7106MM-T C0603C104K8RACTU GRM32ER71A226KE20L GRM32ER71A226KE20L CMS06 CDRH5D18BHHPNP-2R7M MCR03EZPFX4300 MCR03EZPFX1870 MCR03EZPFX4701 MCR03EZPFX4701 160-2043-02-01-00 5000 3 Manufacturer National Semiconductor Taiyo Yuden Kemet Murata Murata Toshiba Sumida Rohm Rohm Rohm Rohm Cambion Keystone www.national.com ...

Page 4

PCB Layout Top Layer and Overlay Internal Layer 2 www.national.com 30087205 Internal Layer 1 30087207 4 30087206 30087208 Bottom Layer ...

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 and Timing www.national.com/timing Data Converters www.national.com/adc Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www ...

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