Datasheet

LM22674-ADJ
+
GND
+
VIN
EN
SW
BOOT
FB
GND
VIN 4.5V to 42V
C2
22 PF
C1
2.2 PF
EN
C3
10 nF
L1
39 PH
C4
22 PF
GND
R
FBT
1.54 k:
R
FBB
976:
D1
60V, 1A
VOUT 3.3V
100 1k 10k 100k 1M 10M
0
5
10
15
20
25
30
35
40
COMPENSATOR GAIN (dB)
FREQUENCY (Hz)
-ADJ
-5.0
LM22674
SNVS590L –SEPTEMBER 2008–REVISED APRIL 2013 www.ti.com
(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 14. 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 APPLICATION
Figure 15 shows an example of converting an input voltage range of 5.5V to 42V, to an output of 3.3v at 0.5A.
See the application note for the LM22671, AN-1895 (SNVA368), for more information.
Figure 15. Typical Buck Regulator Application
EXTERNAL COMPONENTS
The following guidelines should be used when designing a step-down (buck) converter with the LM22674.
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