The C_TMR programs the over current protection delay (t_OC) and auto-retry time (t_RETRY). Once the voltage across CS+ and CS– exceeds the set point, the C_TMR starts charging with 80-µA pull-up current. After the C_TMR charges up to V_{(TMR_FLT)}, FLT asserts low providing warning on impending FET turn OFF. After C_TMR charges to V_{(TMR_OC)}, PD pulls low to SRC turning OFF the FET. Post this event, the auto-retry behavior starts. The C_TMR capacitor starts discharging with 2.5-uA pulldown current. After the voltage reaches V_{(TMR_LOW)} level, the capacitor starts charging with 2.5-uA pullup. After 32 charging-discharging cycles of C_TMR the FET turns ON back and FLT de-asserts

Use Equation 7 to calculate the C_TMR capacitor to be connected across TMR and GND.

Where, I_TMR is internal pull-up current of 80-µA, t_OC is desired overcurrent response time.

The fastest t_OC is < 6 µs with no C_TMR cap connected.

t_RETRY = 22.7 × 10⁶ × C_TMR

If the overcurrent pulse duration is below t_OC then the FET remains ON and C_TMR gets discharged using internal pull down switch.

Figure 8-9 Overcurrent Protection With Auto-Retry