The converter was designed such that the cycle-by-cycle limiting will begin once the output current reaches roughly 35 A. Given that the peak inductor current at maximum load current is 24.25 A, this provides about 45% margin before an overcurrent event is detected by the controller. The primary side current is being sensed at CS_ILIM, so the turns ratio must be accounted for when calculating the necessary value of the sense resistor. Likewise, a current sense transformer with turns ratio of 1:100 is used to step down the primary current. The following calcuations are used to arrive at the value of R_CS that translates to the desired output overcurrent level.

Equation 71.

Equation 72.

Equation 73.

Equation 74.

Based on the calculation, a 7.5-Ω resistor was selected for R_CS.