RES

SS

LO

HO

5V

t1

Current Limit Detected

at CS

2.5V

0V

+55 2A

+1 2A

t2

t3

1V

CLK

Q

S

R

Drivers Off

SS

PWM

COMP

CS

RES

LM5035

SS

Drivers Off

Voltage

Feedback

Current

Sense

Circuit

Restart

Comparator

Restart

Latch

2.5V

5V

Restart

Current

Source

Logic

SS

Logic

To Output

Drivers

Current

Limit

0.25V

Soft-start

100 mV

55 2A

55 2A

1 2A

22 2A

12 2A

LM5035

SNVS428H – JANUARY 2006 – REVISED OCTOBER 2015

www.ti.com

Feature Description (continued)

The overload-timer function is very versatile and can be configured for the following modes of protection:

Cycle-by-cycle only The hiccup mode can be completely disabled by connecting a zero to 50-k

Ω resistor from

the RES pin to AGND. In this configuration, the cycle-by-cycle protection will limit the output current

indefinitely and no hiccup sequences will occur.

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.

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.

Externally Controlled Hiccup The RES pin can also be used as an input. By externally driving the pin to a level

greater than the 2.5-V 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

overtemperature protection circuit or an output overvoltage sensor.

Figure 11. Current-Limit Restart Circuit

Figure 12. Current-Limit Restart Timing

14

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