LM22676-ADJ

+

GND

+

VIN

EN

SW

BOOT

FB

GND

VIN 4.5V to 42V

C2

22 PF

C1

6.8 PF

EN

C3

10 nF

L1

8.2 PH

C4

120 PF

GND

1.54 k:

976:

D1

60V, 5A

VOUT 3.3V

100

1k

10k

100k

1M

10M

0

5

10

15

20

25

30

35

40

FREQUENCY (Hz)

-ADJ

-5.0

LM22676

LM22676-Q1

www.ti.com

SNVS587K – SEPTEMBER 2008 – REVISED APRIL 2013

(9)

The Q factor depends on the parasitic resistance of the power stage components and is not typically in the

control of the designer. Of course, loop compensation is only one consideration when selecting power stage

components; see the Application Information section for more details.

Figure 15. Compensator Gain

In general, hand calculations or simulations can only aid in selecting good power stage components. Good

design practice dictates that load and line transient testing should be done to verify the stability of the application.

Also, Bode plot measurements should be made to determine stability margins. Application note AN-1889

(SNVA364) shows how to perform a loop transfer function measurement with only an oscilloscope and function

generator.

Application Information

TYPICAL BUCK REGULATOR APPLICAION

Figure 16 shows an example of converting an input voltage range of 5.5V to 42V, to an output of 3.3v at 3A. See

the application note for the LM22670, AN-1885 (SNVA361), for more information.

Figure 16. Typical Buck Regulator Application

EXTERNAL COMPONENTS

The following guidelines should be used when designing a step-down (buck) converter with the LM22676.

Copyright © 2008–2013, Texas Instruments Incorporated

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Product Folder Links: LM22676 LM22676-Q1