The TPSM8281x is protected against overload and short circuit events. If the inductor current exceeds the current limit I_LIMH, the high-side MOSFET is turned off and the low-side MOSFET is turned on to ramp down the inductor current. The high-side MOSFET turns on again only if the current in the low-side MOSFET has decreased below the low-side current limit. Due to internal propagation delays, the actual current can exceed the static current limit. The dynamic current limit is given as:

where

• I_LIMH is the static current limit, as specified in the electrical characteristics
• L is the effective inductance (typically 470nH)
• V_L is the voltage across the inductor (V_IN - V_OUT)
• t_PD is the internal propagation delay of typically 50ns

The dynamic peak current is calculated as follows:

The low-side MOSFET also contains a negative current limit to prevent excessive current from flowing back through the inductor to the input. If the low-side sinking current limit is exceeded, the low-side MOSFET is turned off. In this scenario, both MOSFETs are off until the start of the next cycle. The negative current limit is only active in Forced PWM mode.