JAJSOG7 January 2024 TPS4810-Q1
ADVANCE INFORMATION
The CTMR programs the short-circuit protection delay (tSC) and auto-retry time (tRETRY). Once the voltage across CS+ and CS– exceeds the set point, the CTMR starts charging with 80μA pull-up current.
After CTMR charges to V(TMR_SC), G1PD pulls low to SRC and FLT asserts low providing warning on impending FET turn OFF. Post this event, the auto-retry behavior starts. The CTMR capacitor starts discharging with 2.5µA pulldown current. After the voltage reaches V(TMR_LOW) level, the capacitor starts charging with 2.2µA pullup. After 32 charging-discharging cycles of CTMR the FET turns ON back and FLT de-asserts.
The device retry time (tRETRY) is based on CTMR for the first time as per Equation 7 .
Use Equation 6 to calculate the CTMR capacitor to be connected across TMR and GND.
Where,
ITMR is internal pull-up current of 80μA.
tSC is desired short-circuit response time.
The fastest tSC is with no CTMR cap connected.
If the short-circuit pulse duration is below tSC then the FET remains ON and CTMR gets discharged using internal pull down switch.