LM5007EVAL/NOPB National Semiconductor, LM5007EVAL/NOPB Datasheet

LM5007EVAL/NOPB

Manufacturer Part Number

LM5007EVAL/NOPB

Description

EVALUATION BOARD FOR LM5007

Manufacturer

National Semiconductor

Datasheets

1.LM5007SDNOPB.pdf (12 pages)

2.LM5007EVALNOPB.pdf (6 pages)

Specifications of LM5007EVAL/NOPB

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

10V

Current - Output

400mA

Voltage - Input

12 ~ 75V

Regulator Topology

Buck

Board Type

Fully Populated

Utilized Ic / Part

LM5007

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

Power - Output

Frequency - Switching

Lead Free Status / Rohs Status

Compliant

Other names

*LM5007EVAL
*LM5007EVAL/NOPB
LM5007EVAL

Available stocks

Company

Part Number

Manufacturer

Quantity

Price

Company:

Bonase Electronics (HK) Co., Limited

Part Number:

LM5007EVAL/NOPB

Manufacturer:

National Semiconductor

Quantity:

135

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LM5007 Evaluation Board

Introduction

The LM5007 evaluation board is designed to provide the

design engineer with a fully functional step down switching

regulator to evaluate LM5007 regulator IC,in a typical envi-

ronment.

The performance of evaluation board is as follows:

• Input range: 12V to 75V

• Output voltage: 10V

• Output current: 400mA

• Measured efficiency: 90% at 300mA and V

• Board size: 31.9mm x 44.4mm

Theory Of Operation

The LM5007 Step down switching regulator features all of

the functions needed to implement low cost, efficient, Buck

bias regulators. This high voltage regulator contains an 80V,

0.7A N-channel Buck switch. The regulator is based on

hysteretic control scheme using an on-time inversely propor-

tional to input voltage (V

frequency to remain relatively constant with load and input

voltage voltage variations. The hysteretic control requires no

control loop compensation, while providing fast load tran-

sient response. Additional protection features include : Ther-

mal Shutdown, V

ty–cycle limiter. LM5007 can be used in numerous

applications to efficiently regulate step down higher voltage

inputs. This regulator is well suited for 48V telecom and the

new 42V automotive power bus ranges.

The LM5007 operates in discontinuous conduction mode at

light load currents or continuous conduction mode at heavier

load currents. In discontinuous conduction mode, current

through the output inductor starts at zero and ramps up to

the peak value during the buck switch on time, and then back

to zero during buck switch off time. In discontinuous conduc-

tion mode, the operating frequency can be relatively low and

will vary with load. Therefore at light loads the conversion

efficiency is maintained , since switching losses decrease

with reduction in switching frequency.

undervoltage lockout and maximum du-

). This feature allows the operating

AN200832

= 30V

National Semiconductor

Application Note 1298

Ravi Murugeshappa

January 2004

The evaluation board just needs one high voltage power-

supply (upto 75V and current rating of 1A). The maximum

output power is 4 watts. Either an electronic load or resistor

bank can be used for testing evaluation board.

Start-up Feature

There is no soft-start feature in LM5007, and it normally

comes up with full load current to supply the power de-

manded by the load within a short time.The LM5007 con-

tains an intelligent current limit OFF timer intended to reduce

the foldback characteristic inherent with fixed off-time over-

current protection. If the current in the Buck FET exceeds

725mA the present cycle is immediately terminated (cycle by

cycle current limit). Following the termination of the cycle a

non-resetable current limit off timer is initiated. The duration

of off time is a function of the external setting resistor (Rcl)

and the FB pin voltage. When FB pin voltage = 0V the

current limit off time is internally preset to 15µs. This condi-

tion occurs in short circuit operation when a maximum

amount of off time is required.

In cases of overload (not complete short circuit) the current

limit off time can be reduced as a function of the output

voltage (measured at the FB pin). Reducing the off time

during smaller overloads reduces the amount of foldback

and also reduces the initial start-up time.

Low Ripple Configuration

For applications where lower output voltage ripple is re-

quired the output load can be connected directly to the low

ESR output capacitor, as shown below. The evaluation board

is laid out in such a way that, user can use either (high ripple

or low ripple) options by simply shifting the output connector.

The series resistor (R) will degrade the load regulation how-

ever. Another technique for enhancing the ripple voltage at

the FB pin is to place a capacitor in parallel with the feedback

divider resistor R1. The addition of the capacitor reduces the

attenuation of the ripple voltage from the feedback divider.

www.national.com

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LM5007EVAL/NOPB Summary of contents

Page 1

... Therefore at light loads the conversion efficiency is maintained , since switching losses decrease with reduction in switching frequency. © 2004 National Semiconductor Corporation National Semiconductor Application Note 1298 Ravi Murugeshappa January 2004 The evaluation board just needs one high voltage power- supply (upto 75V and current rating of 1A) ...

Page 2

Low Ripple Configuration www.national.com (Continued) Evaluation Board Schematic Diagram 2 20083201 20083202 ...

Page 3

ITEM PART NUMBER C 1 C4532X7R2A105M C 2 C4532X7R1E156M C 3 C1206C104K5RAC C 4 C1206C103K5RAC C 5 C3216X7R2A104KT D 1 MURA110T3 L 1 SLF7045T-101MR60 CRCW12062003F R 2 CRCW12061003F R 3 CRCW12063011F R 4 CRCW12061001F R 5 CRCW12061R00F U ...

Page 4

Load Current vs Switching Frequency PCB Layouts www.national.com Input Voltage vs Switching Frequency 20083207 Top Layer 4 20083208 20083209 ...

Page 5

PCB Layouts (Continued) Silk Screen Bottom Layer 5 20083210 20083211 www.national.com ...

Page 6

... BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials 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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