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DESIGN EXAMPLES
Example 1. A 5-V to 1.8-V DC-to-DC Converter Using a TPS40041
EN
EN
TPS40040 , TPS40041
SLUS700D – MARCH 2006 – REVISED DECEMBER 2007
The following example illustrates the design process and component selection for a 5-V to 1.8-V point-of-load
synchronous buck converter. The design goal parameters are given in the table below. A list of symbol definitions
is found at the end of this section.
Design Goal Parameters
SYMBOL PARAMETER TEST CONDITION MIN TYP MAX UNIT
V
IN
Input voltage 4.5 5.5 V
V
INripple
Input ripple I
OUT
= 6 A 75 mV
V
OUT
Output voltage I
OUT
= 0 A, V
IN
= 5 V 1.764 1.8 1.836 V
Line regulation V
IN
= 4.5 A to 5.5 V 0.5%
Load regulation I
OUT
= 0 A to 6 A 0.5%
V
RIPPLE
Output ripple I
OUT
= 6 A 36 mV
V
TRANS
Transient deviation I
OUT
= 1 A to 5 A, I
OUT
= 5 A to 1 A 50
I
OUT
Output current V
IN
= 4.5 V to 5.5 V 0 6 A
F
SW
Switching frequency 600 kHz
Size 1 In
2
For this example, the schematic shown in Figure 23 is used. The TPS40041, with F
SW
= 600 kHz, is selected to
reduce inductor and capacitor sizes.
Figure 23. TPS40041 Sample Schematic
Copyright © 2006 – 2007, Texas Instruments Incorporated 19
Product Folder Link(s): TPS40040 TPS40041