LM20134EVAL National Semiconductor, LM20134EVAL Datasheet

LM20134EVAL

Manufacturer Part Number

LM20134EVAL

Description

BOARD EVAL 4A POWERWISE LM20134

Manufacturer

National Semiconductor

Series

PowerWise®r

Datasheets

1.LM20134MHNOPB.pdf (22 pages)

2.LM20134EVAL.pdf (8 pages)

Specifications of LM20134EVAL

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

1.2V

Current - Output

Voltage - Input

2.95 ~ 5.5V

Regulator Topology

Buck

Board Type

Fully Populated

Utilized Ic / Part

LM20134

Lead Free Status / RoHS Status

Not applicable / Not applicable

Power - Output

Frequency - Switching

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LM20134 Evaluation Board

Introduction

The LM20134 is a full featured buck switching regulator ca-

pable of driving up to 4A of load current. This device features

a clock synchronization input that allows the switching fre-

quency to be synchronized to an external clock source. The

flexibilty to synchronize the switching frequency from 500 kHz

to 1.5 MHz allows the size of the power stage components to

be reduced while still allowing for high efficiency. The

LM20134 is capable of converting an input voltage between

2.95V and 5.5V down to an output voltage as low as 0.8V.

Fault protection features include cycle-by-cycle current limit,

output power good, and output over-voltage protection. The

dual function soft-start/tracking pin can be used to control the

startup response of the LM20134, and the precision enable

pin can be used to easily sequence the LM20134 in applica-

tions with sequencing requirements. The LM20134 is avail-

able in an eTSSOP-16 package with an exposed pad for

enhanced thermal performance.

300327

FIGURE 1. Evaluation Board Schematic

National Semiconductor

Application Note 1689

Dennis Hudgins

October 30, 2007

The LM20134 evaluation board has been designed to bal-

ance overall solution size with the efficiency of the regulator.

The evaluation board measures just under 1.3” x 1.1” on a

two layer PCB, with all components placed on the top layer.

The power stage and compensation components of the

LM20134 evaluation board have been optimized for an input

voltage of 5V, but for testing purposes, the input can be varied

across the entire operating range. The output voltage of the

evaluation board is nominally 1.2V, but this voltage can be

easily changed by replacing one of the feedback resistors

LM20134 evaluation board has been designed to provide a

stable solution over the entire input and output voltage range

with a reasonable transient response. The EN pin must be

above 1.18V (typ) on the board to initiate switching. If the EN

function is not necessary, the EN pin should be externally tied

to V

FB1

or R

FB2

). The control loop compensation of the

30032701

www.national.com

Related parts for LM20134EVAL

LM20134EVAL Summary of contents

Page 1

... The LM20134 is avail- able in an eTSSOP-16 package with an exposed pad for enhanced thermal performance. © 2007 National Semiconductor Corporation National Semiconductor Application Note 1689 Dennis Hudgins October 30, 2007 The LM20134 evaluation board has been designed to bal- ance overall solution size with the efficiency of the regulator. The evaluation board measures just under 1.3” ...

Page 2

Bill of Materials Designator Description U1 Synchronous Buck Regulator C 100 µF, 1210, X5R, 6. µF, 0603, X5R, 6.3V BYP C 100 µF, 1210, X5R, 6.3V OUT L 1.5 µH, 8.1 mΩ 1Ω, 0603 ...

Page 3

Performance Characteristics Efficiency vs Load Load Regulation (V IN 30032715 = 5V) 0. Load Transient Response 30032717 Startup Waveform 30032720 3 Line Regulation (I = 4A) LOAD 30032716 (200 µs/DIV) 30032719 www.national.com ...

Page 4

Component Selection This section provides a walk-through of the design process of the LM20134 evaluation board. Unless otherwise indicated all equations assume units of Amps (A) for current, Farads (F) for capacitance, Henries (H) for inductance, and Volts (V) for ...

Page 5

C calculating the value for R as outlined in the next section Once the value known, resistor zero in the control loop ...

Page 6

PCB Layout www.national.com Top Layer Bottom Layer 6 30032713 30032714 ...

Page 7

Notes 7 www.national.com ...

Page 8

... 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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