LM2650EVAL/NOPB National Semiconductor, LM2650EVAL/NOPB Datasheet

LM2650EVAL/NOPB

Manufacturer Part Number

LM2650EVAL/NOPB

Description

EVALUATION BOARD FOR LM2650X

Manufacturer

National Semiconductor

Datasheets

1.LM2650M-ADJNOPB.pdf (11 pages)

2.LM2650EVALNOPB.pdf (6 pages)

Specifications of LM2650EVAL/NOPB

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

1.5 ~ 16V

Current - Output

Voltage - Input

4.5 ~ 18V

Regulator Topology

Buck

Board Type

Fully Populated

Utilized Ic / Part

LM2650

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

Power - Output

Frequency - Switching

Other names

*LM2650EVAL
*LM2650EVAL/NOPB
LM2650EVAL

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Information About the

LM2650 Evaluation Board

Rev. 1

Introduction

A printed circuit board (PCB) has been developed. This

application note contains information about the board.

General Description

The LM2650 evaluation board is provided as a tool for

developing DC/DC converters based on the LM2650 IC. It is

configured for single-output, step-down DC/DC converters.

Figure 1 is a complete schematic of the board which can

accommodate up to 28 components including the LM2650.

Table 1 is a complete list of pads for placing components.

Note: Not all applications will require the placement of all 28

components. The number of components placed depends

on the requirements of the application and the use of fea-

tures like programmable soft-start. The LM2650 evaluation

board is intended to be a reusable tool on which many

different converters meeting the requirements of many dif-

ferent applications can be built. It is not intended to demon-

strate only one application of the LM2650.

Thermal Performance

The 24-lead SO package is a molded plastic package with a

solid copper lead frame. Most of the heat generated at the

die flows through the lead frame into the 3-ounce copper

planes on the board. The board then acts as a heat sink. The

junction-to-ambient thermal resistance of the packaged IC

mounted on the board has been measured to be 38˚C/W, 37

˚C/W, and 35 ˚C/W for the dissipation of 1.0W, 1.5W, and

FIGURE 1. The LM2650 Evaluation Board Rev. 1 Schematic

AN100011

National Semiconductor

Application Note 1071

Steven Hunt

October 1997

For convenience, a sample of the LM2650 and eight other

components have been assembled: a 0.1 µF capacitor at

each of C1, C2, C6, and CB, a 0.2 µF capacitor at CVDD, a

0.01 µF capacitor at CSS, a 24.9 kΩ resistor at R2, and a 0Ω

resistor at R4. Of the eight, the first seven are common to

many applications, and the last is simply a jumper grounding

the SYNC input. When the synchronization feature is not

being used, the SYNC input should be grounded.

Example Circuits

The components contained in Tables 2, 3, and 4 can be used

to build typical application circuits. As with the design of any

DC/DC converter, the design of these involved tradeoffs

between efficiency, size, and cost. The converters detailed in

Table 2 were designed with efficiency as the number one

criteria. Those detailed in Table 4 trade slightly higher switch-

ing losses for a much smaller inductor.

2.0W respectively. These measurements were made in still

air. The junction-to-ambient thermal resistance of the pack-

aged IC alone in still air is 78˚C/W. The board is 0.063’ thick

FR-4 material.

Art

Figure 2 through Figure 4 show the PCB art work.

www.national.com

10001105

Related parts for LM2650EVAL/NOPB

LM2650EVAL/NOPB Summary of contents

Page 1

... The board then acts as a heat sink. The junction-to-ambient thermal resistance of the packaged IC mounted on the board has been measured to be 38˚C/W, 37 ˚C/W, and 35 ˚C/W for the dissipation of 1.0W, 1.5W, and © 2002 National Semiconductor Corporation National Semiconductor Application Note 1071 Steven Hunt ...

Page 2

TABLE 1. A Complete List of Pads for Placing Components Label # U1 1 C1, C2, C3, and C10 CIN1 and CIN2 2 COUT1, COUT2, and COUT3 ...

Page 3

TABLE 2. Components for Two Typical 90 kHz Application Circuits (Continued) Sleep Resistors RSIA and RSIA = 33 kΩ, RSOA = 200 kΩ RSOA TABLE 3. Toroidal Inductors Using Cores from MICROMETALS, INC. Core # 15 µH T38 20 µH ...

Page 4

FIGURE 2. LM2650 Evaluation Board Top Silk Screen (Scale 1:1) FIGURE 3. LM2650 Evaluation Board Bottom Silk Screen (Scale 1:1) www.national.com 10001101 10001102 4 ...

Page 5

FIGURE 4. LM2650 Evaluation Board Component Side (Scale 1:1) FIGURE 5. LM2650 Evaluation Board Solder Side (Scale 1:1) 5 10001103 10001104 www.national.com ...

Page 6

... NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant ...

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