Datasheet

Soft
Start
Control
Switch
Control
V
IS1
EN1
SW1
IS1
IN1
SS1
V
IN
Current
Limit
V
SS1
V
EN1
Time
C
IN
, MIN +
(1ń2)L
(
DI
L
)
2
V
(
RIPPLE
)
V
IN
[
(1ń2)L
ǒ
0.3 I
OUT
Ǔ
2
V
(
RIPPLE
)
V
IN
TPS75003
www.ti.com SBVS052I –OCTOBER 2004–REVISED AUGUST 2010
Figure 23. Soft-Start Circuitry
Figure 24. Soft-Start Timing Diagram
Input Capacitor C
IN1
, C
IN2
Selection (Buck Controllers)
It is good analog design practice to place input capacitors near the inputs of the device in order to ensure a low
impedance input supply. 10mF to 22mF of capacitance for each buck converter is adequate for most applications,
and should be placed within 100mils (0.01in, or 2.54mm) of the IN1 and IN2 pins to minimize the effects of
pulsed current switching noise on the soft-start circuitry during the first ~1V of output voltage ramp. Low ESR
capacitors also help to minimize noise on the supply line. The minimum value of capacitance can be estimated
using Equation 3:
(3)
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