Datasheet

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
CLK
5V
Restart
Comparator
Q
S
R
Drivers Off
Restart
Latch
SS
Current
Limit
To Output
Drivers
PWM
COMP
CS
RES
Voltage
Feedback
SS
Restart
Current
Source Logic
Drivers Off
SS
Logic
Current
Sense Circuit
C
RES
18 PA
100 PA
LM25037
Soft-start
1PA
+5V
+5V
8 PA
2.0V
0.25V
C
SS
100 mV
LM25037, LM25037-Q1
www.ti.com SNVS572D –JULY 2008–REVISED MARCH 2013
an overload by leaving the RES pin open circuit. In this configuration, the first detection of current limit
condition by the CS pin comparator will initiate a hiccup cycle with SS capacitor fully discharged and a
delayed restart.
3. Delayed Hiccup: Connecting a capacitor to the RES pin provides a programmed interval of cycle-by-cycle
limiting before initiating a hiccup mode restart, as previously described. The dual advantages of this
configuration are that a short term overload will not cause a hiccup mode restart but during extended
overload conditions, the average dissipation of the power converter will be very low.
4. Externally Controlled Hiccup: The RES pin can also be used as an input. By externally driving the pin to a
level greater than the 2.0V hiccup threshold, the controller will be forced into the delayed restart sequence.
For example, the external trigger for a delayed restart sequence could come from an over-temperature
protection circuit or an output over-voltage sensor
Figure 15. Current Limit Restart Circuit
Figure 16. Current Limit Restart Timing
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