The TPS6215x devices have protection against heavy-load and short-circuit events. At heavy loads, the current limit determines the maximum output current. If the current limit is reached, the high-side FET is turned off. Avoiding shoot-through current, then the low-side FET switches on to allow the inductor current to decrease. The low-side current limit is typically 1.2 A. The high-side FET turns on again only if the current in the low-side FET has decreased below the low-side current-limit threshold.

The output current of the device is limited by the current limit (see Section 7.5). Due to internal propagation delay, the actual current can exceed the static current limit during that time. The dynamic current limit is calculated as follows:

Equation 4.

where

• I_LIMF is the static current limit, specified in the Section 7.5
• V_L is the voltage across the inductor (V_IN – V_OUT)
• L is the inductor value
• t_PD is the internal propagation delay

The current limit can exceed static values, especially if the input voltage is high and the application uses very small inductances. Calculate the peak current in the dynamic high-side switch using the following equation:

Equation 5.