ffddoo
Newbie level 6

Hi!
I'm designing an usb circuit using a FT232. The circuit gets it's power from the 5V USB power and uses 5V and 3.3V (through a 5V to 3.3V LDO). When the USB is in idle I have to swith power off, so I think the best option is a P channel MOSFET.
I've a signal PWREN from the FT232, it is HIGH when the usb is suspended and LOW when the USB is ok (power enable).
If all the power signals in my system were 5V I would use a P channel mosfet to swith it off, the source of the mosfet to the 5V power USB, the PWREN to the gate of the mosfet and the drain to the rest of the circuit.
The problem is that PWREN is a 3.3V signal so It will switch off the mosfet ever.
I'm trying to figure out different ways of triggering the mosfet but I don't find good enough any of them.
Any ideas please?
Thanks in advance
I'm designing an usb circuit using a FT232. The circuit gets it's power from the 5V USB power and uses 5V and 3.3V (through a 5V to 3.3V LDO). When the USB is in idle I have to swith power off, so I think the best option is a P channel MOSFET.
I've a signal PWREN from the FT232, it is HIGH when the usb is suspended and LOW when the USB is ok (power enable).
If all the power signals in my system were 5V I would use a P channel mosfet to swith it off, the source of the mosfet to the 5V power USB, the PWREN to the gate of the mosfet and the drain to the rest of the circuit.
The problem is that PWREN is a 3.3V signal so It will switch off the mosfet ever.
I'm trying to figure out different ways of triggering the mosfet but I don't find good enough any of them.
Any ideas please?
Thanks in advance