To avoid an accidental large peak current, an internal cycle-by-cycle current limit is adopted. The low-side switch is turned off immediately as soon as the switch current touches the limit. The peak switch current limit can be set by a resistor at the ILIM pin to ground. The relationship between the current limit and the resistance depends on the status of the MODE pin.

When the MODE pin is floating, namely the TPS61088, is set to work in the PFM mode at light load, use Equation 3 to calculate the resistor value:

Equation 3.

where

• R_ILIM is the resistance between the ILIM pin and ground
• I_LIM is the switch peak current limit

When the resistor value is 100 kΩ, the typical current limit is 11.9 A.

When the MODE pin is connected to ground, namely the TPS61088 is set to work in forced PWM mode at light load, use Equation 4 to calculate the resistor value.

Equation 4.

When the resistor value is 100 kΩ, the typical current limit is 10.3 A.

Considering the device variation and the tolerance over temperature, the minimum current limit at the worst case can be 1.3 A lower than the value calculated by above equations.