I'm designing a simple board with a FitiPower FP6717 step-up converter chip (Datasheet) and a mechanical switch (SPDT) to enable or disable the output power. My design for the boost will be very close to the typical application circuit in the datasheet. What is the best practice in terms of switch location? Here are the two options I've narrowed it down to:
- Enable/disable the input power from a battery with a PFET at the input with the switch (VCC goes to the Vin pin of the FP6717):
- Enable/disable the input power by switching the EN pin on the FP6717 between GND and Vin:
Is there a "correct" answer to this? My gut tells me to put it on the EN pin, since there will be some non-zero power dissipated over the PFETs RDS(ON), which would decrease the overall efficiency from the battery to the output.