Programming the Overcurrent Protection Threshold – R_ILIM Selection

The R_ILIM sets the overcurrent protection (circuit breaker detection) threshold, whose value can be calculated using Equation 11.

Equation 11.

To set 10 A as overcurrent protection threshold, R_ILIM value is calculated to be 60 kΩ. Choose the closest available standard value: 60 kΩ, 1%.

Programming the Circuit Breaker Time – C_TMR Selection

For the design example under discussion, overcurrent transients are allowed for 1-ms duration. This blanking interval, T_OC (or circuit breaker interval, T_CB) can be set by selecting appropriate capacitor C_TMR from TMR pin to ground. The value of CTMR to set 1 ms for TOC can be calculated using Equation 12.

Equation 12.

Choose closest available standard value: 68 nF, 10%.

Programming Current Monitoring Output – R_IMON Selection

Voltage at IMON pin V_IMON is proportional to the output load current. This can be connected to an ADC of the downstream system for monitoring the operating condition and health of the system. The R_IMON must be selected based on the maximum load current and the input voltage range of the ADC used. R_IMON is set using Equation 13.

Equation 13.

For this application example, VIMON is selected to be 2.7 V at full load current of 5 A. RIMON value of 30.1 kΩ, 1% is selected.