STCC5021 datasheet(20/37 Pages) STMICROELECTRONICS

20 / 37 page

Application information

STCC5011, STCC5021

20/37

DocID024660 Rev 6

Figure 10. Reset of CHARGING/ATTACH and 3-hour timer after EN -> 0 event

5.7

Power switch

Overcurrent conditions

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

and reduces the voltage accordingly. There are two overload conditions:

•

The first one occurs when a short-circuit or a partial short-circuit is already present

when the device is being powered up or enabled. The output voltage is held near zero

potential with respect to ground and the STCC50x1 device ramps the output current to

IOS until the overload condition is removed or the device starts thermal cycle.

•

The second condition is when a short-circuit, a partial short-circuit, or a transient

overload occurs while the device is already enabled and powered-on. The STCC50x1

device responds to the overcurrent condition within time tIOS. The current sense

amplifier is overdriven during this time and momentarily disables the internal current

limit MOSFET. It then recovers and ramps the output current to IOS. Similar to the

previous condition, it limits output current to IOS until the overload condition is removed

or thermal cycle starts.

Thermal protection

The STCC50x1 devices have an internal thermal sensing circuit which monitors the

operating temperature of the circuit. It disables power switch operation if die temperature

exceeds temperature threshold TSTOP, set at 150 °C. The thermal sensor has a hysteresis

of 20 °C. The switch turns on if the temperature has cooled down by 20 °C.

Undervoltage lockout

The UVLO circuit disables the circuit until the input voltage reaches the UVLO turn-on

threshold. Built-in hysteresis prevents unwanted on/off cycling due to input voltage drop

during turn-on.

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