Datasheet

DESIGN EXAMPLES
Example 1: Detailed Design of a 12-V to 5-V and 3.3-V Converter
DESIGN EXAMPLE 1 GENERAL DESCRIPTION
TPS55383 , , TPS55386
SLUS818 SEPTEMBER 2008 .........................................................................................................................................................................................
www.ti.com
The following example illustrates a design process and component selection for a 12-V to 5-V and 3.3-V dual
non-synchronous buck regulator using the TPS55386 converter. Design Example, and List of Materials is found
at the end of this section.
PARAMETER NOTES AND CONDITIONS MIN NOM MAX UNIT
INPUT CHARACTERISTICS
V
IN
Input Voltage 9.6 12.0 13.2 V
I
IN
Input Current V
IN
= Nom, I
OUT1
= I
OUT2
= Max 2.4 2.6 A
No Load Input Current V
IN
= Nom, I
OUT
= 0 A 12 20 mA
V
IN_UVLO
Input UVLO I
OUT
= Min to Max 4.0 4.2 4.4 V
OUTPUT CHARACTERISTICS
V
OUT1
Output Voltage 1 V
IN
= Nom, I
OUT
= Nom 4.80 5.0 5.20 V
V
OUT2
Output Voltage 2 V
IN
= Nom, I
OUT
= Nom 3.20 3.3 3.40 V
Line Regulation V
IN
= Min to Max 1%
Load Regulation I
OUT
= Min to Max 1%
V
OUT_ripple
Output Voltage Ripple V
IN
= Nom, I
OUT
= Max 50 mVpp
I
OUT1
Output Current 1 V
IN
= Min to Max 0 3.0 A
I
OUT2
Output Current 2 V
IN
= Min to Max 0 3.0 A
I
OCP1
Output Over Current Channel 1 V
IN
= Nom, VOUT = V
OUT1
5% 3.3 4.2 5.2 A
I
OCP2
Output Over Current Channel 2 V
IN
= Nom, VOUT = V
OUT2
5% 3.3 4.2 5.2 A
Transient Response
Δ Vout from load transient Δ I
OUT
= 1 A at 3 A/ µ s 200 mV
Settling Time To 1% of Vout 1 ms
SYSTEM CHARACTERISTICS
f
SW
Switching Frequency 500 600 700 kHz
η
pk
Peak Efficiency V
IN
= Nom, I
OUT1
= I
OUT2
93%
η Full Load Efficiency VI
N
= Nom, I
OUT1
= I
OUT2
= Max 86%
Top Operating Temperature Range V
IN
= Min to Max, I
OUT
= Min to Max 0 25 60 ° C
Figure 33. Design Example Schematic
30 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): TPS55383 TPS55386