Datasheet

TPS54290, TPS54291, TPS54292
SLUS973 –OCTOBER 2009 www.ti.com
DESIGN EXAMPLES
Design Example 1
The following example illustrates the design process and component selection for a 12-V to 5-V and 3.3-V dual
non-synchronous buck regulator using the TPS54291 converter. A definition of symbols used can be found in
Table 1 of the appendix
Table 1. Design Example Electrical Characteristics
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
INPUT CHARACTERSTICS
V
IN
Input voltage 8 12 14 V
I
IN
Input current V
IN
= Nom, I
OUT
= Max 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 4.2 4.4 V
OUTPUT CHARACTERSTICS
V
OUT1
Output voltage 1 V
IN
= Nom, I
OUT
= Nom 3.2 3.3 3.4 V
V
OUT2
Output voltage 2 V
IN
= Nom, I
OUT
= Nom 1.15 1.20 1.25 V
Line regulation VIN = Min to Max 1%
Load regulation I
OUT
= Min to Max 1%
V
OUT1(ripple)
Output1 voltage Ripple V
IN
= Nom, I
OUT1
= Max 50 mV
PP
V
OUT2(ripple)
Output2 voltage Ripple V
IN
= Nom, I
OUT2
= Max 24 mV
PP
I
OUT1
Output current 1 V
IN
= Min to Max 0 1.5 A
I
OUT2
Output current 2 V
IN
= Min to Max 0 2.5 A
I
OCP1
Output overcurrent Channel 1 V
IN
= Nom, V
OUT
= (V
OUT1
– 5%) 1.8 2.2 2.6 A
I
OCP2
Output overcurrent Channel 2 V
IN
= Nom, V
OUT
= (V
OUT2
– 5%) 3.2 3.8 4.6 A
TRANSIENT RESPONSE
ΔV
OUT
Change from load transient ΔI
OUT
= 1 A @ 3 µA/s 200 mV
Settling time to 1% of V
OUT
1 ms
SYSTEMS CHARACTERSTICS
f
SW
Switching frequency 500 600 700 kHz
η
PEAK
Peak efficiency V
IN
= Nom 90%
η Full load efficiency V
IN
= Nom, I
OUT
= Max 80%
T
OP
Operating temperature range V
IN
= Min to Max, I
OUT
= Min to Max 0 25 60 °C
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