STCC5011 Datasheet, PDF (20/37 Pages) STMicroelectronics – Constant current mode overcurrent protection

Application information
STCC5011, STCC5021
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
I_OS 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 t_IOS. 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 I_OS. Similar to the
previous condition, it limits output current to I_OS 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 T_STOP, 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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