RES

SS

OUTA

OUTB

0V

1V

5V

t1

t 2

t3

Current Limit Detected

at CS

12A

Current Limit Persists

100 2A

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

100 mV

SS

Logic

Current

Sense Circuit

18 2A

8 2A

100 2A

LM5037

Soft-start

12A

0.25V

+5V

+5V

2.0V

LM5037

SNVS578D – NOVEMBER 2008 – REVISED MAY 2015

www.ti.com

Device Functional Modes (continued)

7.4.1.1.2

Hiccup Only

The timer can be configured for immediate activation of a hiccup sequence upon detection of an overload by

leaving the RES pin open circuit. In this configuration, the first detection of current limit condition by the CS pin

comparator initiates a hiccup cycle with SS capacitor fully discharged and a delayed restart.

7.4.1.1.3

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 does not cause a hiccup mode restart but during extended overload conditions, the average dissipation

of the power converter remains very low.

7.4.1.2 Externally Controlled Hiccup

The RES pin can also be used as an input. The RES pin forces the device into a delayed restart sequence when

the pin rises to a level greater than the 2.0 V hiccup threshold. For example, an external trigger for a delayed

restart sequence may come from an over-temperature protection circuit or an output over-voltage sensor.

Figure 16. Current Limit Restart Circuit

Figure 17. Current Limit Restart Timing

18

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