LM2852X-2.5EVAL National Semiconductor, LM2852X-2.5EVAL Datasheet

LM2852X-2.5EVAL

Manufacturer Part Number

LM2852X-2.5EVAL

Description

BOARD EVAL LM2852X-2.5

Manufacturer

National Semiconductor

Series

PowerWise®, SIMPLE SWITCHER®r

Datasheets

1.LM2852YMXA-3.3NOPB.pdf (14 pages)

2.LM2852X-1.2EVAL.pdf (4 pages)

Specifications of LM2852X-2.5EVAL

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

2.5V

Current - Output

Voltage - Input

2.85 ~ 5.5V

Regulator Topology

Buck

Frequency - Switching

1.5MHz

Board Type

Fully Populated

Utilized Ic / Part

LM2852

Lead Free Status / RoHS Status

Not applicable / Not applicable

Power - Output

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LM2852X Demonstration

Board

Introduction

This application note describes the demonstration board for

the LM2852X. The LM2852 is a 2A buck regulator belonging

to National Semicondutor’s SIMPLE SYNCHRONOUS

family. The LM2852 input voltage can range from 2.85V to

5.5V. Output voltages are factory set from 0.8V to 3.3V in

100mV increments. On-chip type-three compensation facili-

tates simple, low component count power supply design.

Two frequency versions of the LM2852 are available: 500

kHz (LM2852Y) and 1500 kHz (LM2852X). The demonstra-

tion board for the LM2852X (1500 kHz version) is described

in this application note. A separate application note de-

scribes the LM2852Y. For detailed information regarding

component selection, consult the datasheet.

Three solder terminals are provided for connections to V

GND and V

nected to two PVIN pins and an AVIN pin. PVIN is the supply

connected to the output power switches; AVIN powers the

controller logic of the regulator. The demonstration board

includes filtering of the AVIN voltage using components R

and C

ground through the solder terminal via as well as vias under-

neath the exposed DAP of the LM2852.

Enable (EN)

The LM2852 enable pin is internally pulled up through a

large resistance. The demonstration board includes a via

connected to the EN line to facilitate soldering a jumper wire

if application of an enable signal is desired.

, GND and V

. The back side plane of the board is connected to

OUT

. The input voltage to the LM2852 is con-

OUT

AN201654

National Semiconductor

Application Note 1397

Thatcher Klumpp

September 2005

The demonstration board provides two capacitor footprints

for the input capacitance. The larger footprint holds the bulk

of the capacitance, for example 47 µF. Additional high fre-

quency filtering may also be accomplished by adding a

smaller capacitor – C

commonly used for high frequency filtering.

The soft-start capacitor is used to control the startup behav-

ior of the switching regulator. A 2.7 nF capacitor yields

approximately a 3 ms startup time.

Output Filter - L, and C

Since the LM2852 uses on-chip compensation, the output

filter component values must be restricted to a certain range.

The LM2852X is designed for ceramic output capacitors with

ESR values below 10 mΩ. The recommended inductance

and capacitance for standard input and output voltages are 1

µH and 10 µF.

and C

INX

. A 1 µF or 100 nF capacitor is

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Related parts for LM2852X-2.5EVAL

LM2852X-2.5EVAL Summary of contents

Page 1

... Two frequency versions of the LM2852 are available: 500 kHz (LM2852Y) and 1500 kHz (LM2852X). The demonstra- tion board for the LM2852X (1500 kHz version) is described in this application note. A separate application note de- scribes the LM2852Y. For detailed information regarding component selection, consult the datasheet ...

Page 2

... Board Schematic Bill of Materials for 1500 kHz Solution (LM2852X) ID Part Number U LM2852XMXA-x DO1608C-102 C GRM31MR61A106KE19 O C GRM31CR60J476M IN C GRM188R61A105K INX C VJ0603Y272KXXA SS R CRCW060310R0F F C GRM188R61A105K F 160-1026-02-05-00 www.national.com Type Size 2A Buck ETSSOP-14 Inductor Capacitor 1206 Capacitor 1206 Capacitor 0603 Capacitor 0603 Resistor 0603 ...

Page 3

... PCB Layouts: 835 (mil) X 850 (mil) Top Layer Efficiency Plot 20165402 LM2852X Typical Efficiency for 2.5V Output 3 20165403 Bottom Layer 20165404 www.national.com ...

Page 4

... 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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