LM20133EVAL National Semiconductor, LM20133EVAL Datasheet

LM20133EVAL

Manufacturer Part Number

LM20133EVAL

Description

BOARD EVAL 3A POWERWISE LM20133

Manufacturer

National Semiconductor

Series

PowerWise®r

Datasheets

1.LM20133MHNOPB.pdf (22 pages)

2.LM20133EVAL.pdf (8 pages)

Specifications of LM20133EVAL

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

LM20133

Lead Free Status / RoHS Status

Not applicable / Not applicable

Power - Output

Frequency - Switching

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LM20133 Evaluation Board

Introduction

The LM20133 is a full featured buck switching regulator ca-

pable of driving up to 3A 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

LM20133 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 LM20133, and the precision enable

pin can be used to easily sequence the LM20133 in applica-

tions with sequencing requirements. The LM20133 is avail-

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

enhanced thermal performance.

300326

FIGURE 1. Evaluation Board Schematic

National Semiconductor

Application Note 1688

Dennis Hudgins

October 30, 2007

The LM20133 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

LM20133 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

LM20133 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

30032601

www.national.com

Related parts for LM20133EVAL

LM20133EVAL Summary of contents

Page 1

... The LM20133 is avail- able in an eTSSOP-16 package with an exposed pad for enhanced thermal performance. © 2007 National Semiconductor Corporation National Semiconductor Application Note 1688 Dennis Hudgins October 30, 2007 The LM20133 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

... This terminal connects to the SYNC pin of the device. If this pin is left open the switching frequency will default to approximately 400kHz. The voltage on this pin should not exceed 5.5V during normal operation and has an absolute maximum voltage rating of 6V. 2 Qty Manufacturer 1 National Semiconductor 1 Murata 1 Murata 1 Murata ...

Page 3

Performance Characteristics Efficiency vs Load Load Regulation (V IN 30032615 = 5V) 0. Load Transient Response 30032617 Startup Waveform 30032620 3 Line Regulation (I = 3A) LOAD 30032616 (200 µs/DIV) 30032619 www.national.com ...

Page 4

Component Selection This section provides a walk-through of the design process of the LM20133 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 30032613 30032614 ...

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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