LM2852Y-1.2EVAL National Semiconductor, LM2852Y-1.2EVAL Datasheet

LM2852Y-1.2EVAL

Manufacturer Part Number

LM2852Y-1.2EVAL

Description

BOARD EVAL LM2852Y-1.2

Manufacturer

National Semiconductor

Series

PowerWise®, SIMPLE SWITCHER®r

Datasheets

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

2.LM2852Y-1.2EVAL.pdf (4 pages)

Specifications of LM2852Y-1.2EVAL

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

1.2V

Current - Output

Voltage - Input

2.85 ~ 5.5V

Regulator Topology

Buck

Frequency - Switching

500kHz

Board Type

Fully Populated

Utilized Ic / Part

LM2852

Lead Free Status / RoHS Status

Not applicable / Not applicable

Power - Output

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LM2852 Evaluation Board

(500kHz version)

Introduction

This application note describes the evaluation board for the

LM2852Y. Three output voltage options are available; all

three come with the same bill of materials. The board may be

configured in multiple ways providing various enabling

schemes, split-rail operation and filtering options. The

LM2852 is a 2A step-down buck converter belonging to

National’s SIMPLE SYNCHRONOUS

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 facilitates low component

count power supply design. This evaluation board enables

the power supply designer to investigate various functional

configurations.

PVIN and AVIN

The input voltage to the LM2852 is connected 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 switcher. Since PVIN and AVIN are dedicated pins on the

chip, split rail operation is possible. For example, AVIN can

be set to 5V and PVIN to 3.3V. Jumper J

board is used to short together the AVIN and PVIN board

inputs.

Enable (EN)

The LM2852 enable pin is internally pulled up so that the part

is enabled anytime the input voltage exceeds the UVLO

threshold. The evaluation board includes an input for enable

so the user may set the voltage on the enable pin. Jumper J2

also may be used to short the enable pin to AVin. Resistor,

Rp may be used as a pull down resistor to set the enable

input to low.

family. The LM2852

AN201272

on the evaluation

National Semiconductor

Application Note 1343

Thatcher Klumpp

May 2005

Components C

AVIN input. Filtering AVIN may improve line and load regu-

lation by reducing interfering signals on AVIN. 10 Ω and 1 µF

are typical filter components for AVIN.

This evaluation board provides two capacitor footprints for

the C

capacitor, for example 47 µF. Additional high frequency fil-

tering may also be accomplished by adding a smaller ca-

pacitor – C

for high frequency filtering.

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

ior of the switching regulator. A 2.7 nF capacitor yields

approximately a 3 ms start up time.

Output Filter - L

Since the LM2852 uses on-chip compensation, the output

filter component values must be restricted to a certain range.

The datasheet includes a table and information on compo-

nent selection. Generally, the output capacitors must have

ESR values commonly found in Tantalum and non-Tantalum

solution, Niobium Oxide capacitors.

and R

and C

function. The larger footprint holds the bulk of the C

INX

. A 1 µF or 100 nF capacitor is commonly used

INX

and R

may be used to low-pass-filter the

, C

and C

www.national.com

Related parts for LM2852Y-1.2EVAL

LM2852Y-1.2EVAL Summary of contents

Page 1

... Introduction This application note describes the evaluation board for the LM2852Y. Three output voltage options are available; all three come with the same bill of materials. The board may be configured in multiple ways providing various enabling schemes, split-rail operation and filtering options. The LM2852 step-down buck converter belonging to National’ ...

Page 2

... Board Schematic Bill of Materials ID Part Number U LM2852YMXA-1.2, 1 LM2852YMXA-1.8 or LM2852YMXA-2.5 L DO3316P-153 1 C NOSD107M006R0100 O1 C Not Populated O2 C GRM32ER60J476ME20B IN C GRM21BR71C105KA01B INX C VJ0805Y272KXXA SS R CRCW060310R0F f C GRM21BR71C105KA01B f J CRCW06030R0F 1 J Not Populated 2 R Not Populated P www.national.com Type Size Parameters 2A Buck ETSSOP-14 Inductor 15 µH Capacitor 100 µ ...

Page 3

PCB Layouts Top Layer 20127202 20127204 Typical Efficiency for 2.5V Output 3 20127203 Bottom Layer 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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