Hi,
I am using CSD16570Q5BT as a reverse voltage protection FET. My application is 8V-1A and I need minimal resistance in the E-Fuse+FET. This MOSFET has 10-15nF Ciss. During turn-ON this does not affect my slew rate, but only delays the turn-ON slightly. When the TPS24750 fully enhances the MOSFET (13-15Vgs) there is ~200-250nC gate charge.
Datasheet suggests series resistor of at least 1kOhm to any external slew-limiting capacitor connected from TPS24750's gate pin to ground. I have 10nF-1kOhm at that pin. However I don't see a suggestion for series resistor going to the external MOSFET's gate. In the evaluation module's schematic (TPS24750EVM-546) TI does not use a series gate resistor either. I understand this resistor limits the current stress on TPS24750 during a turn-OFF case.
- Why is there a suggestion for series resistor to external capacitor and not also for other capacitive loads on that pin, while a following FET can also have considerable capacitance? Do I need a series resistor to the GATE of CSD16570Q5BT?
- Datasheet suggests MOSFET "Gate Clamp Diode" for applications with >14V input voltage. In an 8V application the Gate voltage can reach +23V. I think I don't need extra clamping diode since TPS24750 already clamps VCC to Gate at 13-15V. And if my input dies, the maximum load stress is 8V. Would you agree that I don't need clamping diodes since my application is below 14V, or is there a risk that in a hard short circuit case the gate-to-source of my MOSFET can see +23V stress?
Kind regards,
Zeki