Datasheet

STMPS2141, STMPS2151, STMPS2161, STMPS2171 Functional description
Doc ID 13793 Rev 6 9/37
3 Functional description
3.1 Fault blanking
The STMPS devices feature a 10 ms fault blanking. Fault blanking allows current limit faults,
including momentary short-circuit faults that occur when hot-swapping a capacitive load,
and also ensures that no fault is issued during power-up. When a load transient causes the
device to enter current limit, an internal counter starts. If the load fault persists beyond the
10 ms fault blanking timeout, the FAULT output asserts “low”. Load transient faults less than
10 ms (typ.) do not cause a FAULT output assertion. Only current limit faults are blanked.
Die overtemperature faults and input voltage drops below the UVLO threshold cause an
immediate fault output.
3.2 Overcurrent/overtemperature protection
In overcurrent or short-circuit condition, the switch limits the current at a value of about
120% of the rated current. If the temperature of the die goes above the limit value, the switch
turns off.
3.3 Fault conditions
In power switch applications, 4 types of fault conditions are common. These fault conditions
and the response of the STMPS21x1 power switches are described in Tabl e 3.
Table 3. Fault conditions
Fault Condition STMPS21x1 action
Short-circuit
Output shorted to GND via resistance
path of < 1 Ω, causing a rapid current
surge.
Reduces output voltage to reduce the
current. Asserts FAULT pin after
a blanking period
Overcurrent
Output connected to a load that sinks
current above threshold.
Reduces output voltage to reduce the
current. Asserts FAULT pin after
a blanking period.
Overheating
Temperature of junction exceeds 135 °C
due to any reason.
Turn OFF output until temperature falls
below 125 °C. Asserts FAULT pin
immediately.
Undervoltage
Input voltage drops below the UVLO
threshold.
Turn OFF output until input voltage rises
above the UVLO threshold plus
hysteresis. Asserts FAULT pin
immediately.