Datasheet

t3 =
C
SS
x 4V
100 PA
= 40k x C
SS
t2 =
C
SS
x 1V
1 PA
= 1M x C
SS
t1 =
C
RES
x 2.0V
18 PA
= 111k x C
RES
RES
SS
OUTA
OUTB
0V
#1
V
5V
t1 t2
t
3
Current Limit Detected
at CS
1PA
Current Limit Persists
100
PA
2.0V
1.25V
STANDBY
0.45V
SHUTDOWN
VIN
5.0V
UVLO
R1
R2
22 PA
OFF
STANDBY
LM25037
LM25037, LM25037-Q1
SNVS572D –JULY 2008–REVISED MARCH 2013 www.ti.com
Figure 28. Remote Standby and Disable Control
HICCUP MODE CURRENT LIMIT RESTART (RES)
The basic operation of the hiccup mode current limit is described in the functional description. The delay time to
the initiation of a hiccup cycle is programmed by the selection of the RES pin capacitor C
RES
as illustrated in
Figure 29.
Figure 29. Hiccup Over-Load Restart Timing
In the case of continuous cycle-by-cycle current limit detection at the CS pin, the time required for C
RES
to reach
the 2.0V hiccup mode threshold is:
(8)
For example, if C
RES
= 0.01 µF the time t1 is approximately 2.0 ms. The cool down time, t2 is set by the soft-start
capacitor (C
SS
) and the internal 1 µA SS current source, and is equal to:
(9)
If C
SS
= 0.01 µF, t2 is ≊10 ms.
The soft-start time t3 is set by the internal 100 µA current source, and is equal to:
(10)
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