TPS22950 datasheet(11/26 Pages) TI

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IOUT

ILIM

Time

VOUT

VIN

FLT

VFLT

TSD

TSDHYS

tLIM

Soft Short on

VOUT

Auto Restart

Into Short

Auto Restart

(Short Removed)

tD,FLT

Figure 8-1. Output Current Limit for Short Circuit Protection (tLIM)

When an overcurrent condition is detected, the device maintains a constant output current and reduces the

output voltage accordingly. Two possible overload conditions can occur.

The first condition is when a short circuit or partial short circuit is present on the output and the ON pin is

toggled high, turning the device on. The output voltage is held near zero potential with respect to ground and the

TPS22950 ramps the output current to ILIM. The TPS22950 device will limit the current to ILIM until the overload

condition is removed or the internal junction temperature of the device reaches thermal shutdown and the device

turns itself off. The device remains off until the junction temperature has lowered to TSDHYS, and the device will

turn itself back on. This will cycle until the overload condition is removed.

The second condition is when a short circuit, partial short circuit, or transient overload occurs after the device

has been fully powered on. The device responds to the overcurrent condition within time tLIM (see figure below),

and before this time the current is able to exceed ILIM. In the case of a fast transient, the current-sense amplifier

is overdriven and momentarily disables the internal power FET. The current-sense amplifier recovers and limits

the output current to ILIM. Similar to the previous case, the TPS22950 limits the current to ILIM until the overload

condition is removed or the internal junction temperature of the device reaches thermal shutdown and begins

thermally cycling on and off.

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TPS22950

SLVSFJ2 – DECEMBER 2020

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