LM2674

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SNVS007F – SEPTEMBER 1998 – REVISED APRIL 2013

D1 - 3.3A, 50V Schottky Rectifier, IR 30WQ05F

L1 - 68

μH Sumida #RCR110D-680L

R1 - 1.5 k

Ω, 1%

For a 5V output, select R2 to be 4.75 k

Ω, 1%

Use a 1% resistor for best stability.

Figure 23. Standard Test Circuits and Layout Guides Adjustable Output Voltage Versions

LM2674 Series Buck Regulator Design Procedure (Fixed Output)

PROCEDURE (Fixed Output Voltage Version)

EXAMPLE (Fixed Output Voltage Version)

To simplify the buck regulator design procedure, Texas Instruments

is making available computer design software to be used with the

SIMPLE SWITCHERline of switching regulators.LM267X Made

operating systems.

Given:

Given:

1. Inductor Selection (L1)

1. Inductor Selection (L1)

A. Select the correct inductor value selection guide from Figure 25,

A. Use the inductor selection guide for the 5V version shown in

Figure 24 or Figure 26 (output voltages of 3.3V, 5V, or 12V

Figure 24.

respectively). For all other voltages, see the design procedure for the

adjustable version.

B. From the inductor value selection guide, identify the inductance

B. From the inductor value selection guide shown in Figure 24, the

region intersected by the Maximum Input Voltage line and the

inductance region intersected by the 12V horizontal line and the

Maximum Load Current line. Each region is identified by an

500mA vertical line is 47

μH, and the inductor code is L13.

inductance value and an inductor code (LXX).

C. Select an appropriate inductor from the four manufacturer's part

C. The inductance value required is 47

μH. From Table 1, go to the

numbers listed in Table 1. Each manufacturer makes a different style L13 line and choose an inductor part number from any of the four

of inductor to allow flexibility in meeting various design requirements. manufacturers shown. (In most instances, both through hole and

Listed below are some of the differentiating characteristics of each

surface mount inductors are available.)

manufacturer's inductors:

Schott: ferrite EP core inductors; these have very low leakage

magnetic fields to reduce electro-magnetic interference (EMI) and

are the lowest power loss inductors

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