Datasheet

TPS40400
SLUS930B –APRIL 2011– REVISED OCTOBER 2011 www.ti.com
Design Example 2: 12-V Input, 5-V Output, 5-A (max) Output Current
Design Example 2 Parameters
The following example illustrates the design process and component selection for a synchronous buck converter
using the TPS40400 controller. The design goal parameters are listed in Table 8.
Table 8. Design Example 2 Electrical Parameters
PARAMETER NOTES AND CONDITIONS MIN NOM MAX UNITS
INPUT CHARACTERISTICS
V
IN
Input voltage 8 12 14 V
I
IN
Input current V
IN
= 8 V, I
OUT
= 5 A 3.5 A
No load input current V
IN
= 12 V, I
OUT
= 0 A 60 mA
V
IN(start)
V
IN
start voltage 7 V
V
IN(stop)
V
IN
stop voltage 6 V
OUTPUT CHARACTERISTICS
V
OUT
Output voltage V
IN
= 12 V, I
OUT
= 5 A 4.75 5.00 5.25 V
Line regulation 8 ≤ V
IN
≤,14 V, I
OUT
= 5 A 0.5%
Load regulation V
IN
= 12 V, 0 A ≤ I
OUT
≤ 5 A 0.5%
Vout_ripple Output ripple voltage V
IN
= 12 V, I
OUT
= 5 A 50 mV
P-P
Iout Output current 8 ≤ V
IN
≤ 14 0 5 A
I
OCP
Output over current inception point V
IN
= 12 V 6.7 8.0 9.3 A
SS Soft-start time (default) 5 ms
Transient response
ΔI Load step 2 A ≤ I
OUT
≤ 5 A 3 A
Load slew rate 1 A/μS
Overshoot 500 mV
Settling time 50 μs
SYSTEM CHARACTERISTICS
f
SW
Switching frequency 300 kHz
η
PK
Peak efficiency V
IN
= 12 V, 0 A ≤ I
OUT
≤ 5 A 90%
η Full load efficiency V
IN
= 12 V, I
OUT
= 5 A 85%
T
OPER
Operating temperature range 8 ≤ V
IN
≤ 14 V, 0 A ≤ I
OUT
≤ 5 A –40 60 °C
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