TPS1HC100-Q1 provides output short-circuit protection to ensure that the device prevents current flow in the event of a low impedance path to GND, removing the risk of damage or significant supply droop. The device is ensured to protect against short-circuit events regardless of the state of the ILIM pins and with up to 28-V supply at 125°C.

Figure 7-10 shows the behavior of the TPS1HC100-Q1 when the device is enabled into a short-circuit.

Figure 7-10 Enable into Short-Circuit Behavior (LATCH = 0)

Due to the low impedance path, the output current rapidly increases until it hits the current limit threshold. Due to the response time of the current limiting circuit, the measured maximum current can temporarily exceed the I_CL value defined as I_{CL_ENPS}, however, it settles to the current limit regulation value. The amount of deglitch timing between when the overload is recognized and when the system begins to react on it is about 2.5 μs.

In this state, high power is dissipated in the FET, so eventually the internal thermal protection temperature for the FET is reached and the device safely shuts down. Then, if LATCH pin is low, the part waits t_RETRY amount of time and turn back on, unless a T_ABS fault was triggered in which case it can AND the t_RETRY timer and the T_HYS temperature reduction.

Figure 7-11 shows the behavior of the TPS1HC100-Q1 when a short-circuit occurs when the device is in the on-state and already outputting current. When the internal pass FET is fully enabled, the current clamping settling time is slower so to ensure overshoot is limit. The device implements a fast-trip level at a level I_OVCR. When this fast-trip threshold is hit, the device immediately shuts off for a short period of time before quickly re-enabling and clamping the current to I_CL level after a brief transient overshoot to the higher peak current (I_{CL_ENPS}) level. The device then keeps the current clamped at the regulation current limit until the thermal shutdown temperature is hit and the device safely shuts off.

Figure 7-11 On-State Short-Circuit Behavior

Overload Behavior shows the behavior of the TPS1HC100-Q1 when there is a small change in impedance that sends the load current above the I_CL threshold. The current rises (commonly referred to as current creep) to I_{CL_LINPK} above the regulation level. Then the current limit regulation loop kicks in and the current drops to the I_CL value.

Figure 7-12 Overload Behavior (Current Creep)

In all of these cases, the internal thermal shutdown is safe to hit repetitively. There is no device risk or lifetime reliability concerns from repeatedly hitting this thermal shutdown level.