Good day. I trust you are doing well? We are busy with a design where we wish to use the LM74700 for reverse current protection on the input.
Where I am a bit concerned is that TI suggests to choose (20 mV / ILoad(Nominal)) ≤ RDS(ON) ≤ ( 50 mV / ILoad(Nominal)).
Our typical nominal current is very low, ie <100mA in most cases, but once our various loads are switched on, this can go to 1A in some cases, and exceed 4A in others.
The absolute minimum vs max currents is thus vary wide, which make compliance to the suggested RDS range as per the above formula difficult. Which should we always comply to?
20mV accross Vds during nominal, minimum current operation? Thus, is it ok if we exceed 50mV significantly? However, choosing a mosfet with higher Rds to meet minimum 20mV drop, would mean that we go unnecessarily high on the Mosfet Rds, leading to unnecessary heat dissipation at our >4A conditions.
If on the other hand, we design for lowest Rds, to ensure minimum heat dissipation at high currents (even up to the mosfet max current rating), we will not meet minimum 20mV drop on very low current conditions such as MCU only running. Or can the LM74700 still adequately operate and ensure proper reverse protection even at much lower Vds drops than 20mV? I hope my question makes sense. I look forward to your feedback. Thanking you in advance. Regards, Kevin
