I am trying to find or design a power saver circuit for a portable device. I figured this would be a fairly common circuit, maybe I am just missing the keywords to search. Basically I need to shut all power if a signal is not pulled back to ground after 5 minutes. This signal is an active low, "device active" signal. I originally tried 555 as a delay off driving a P channel mosfet whose source is the Vout and drain is Vbat, but had no luck. Here are some parameters:
Vbat: battery voltage - 4.5 volts
Vout: Can go as low a 3.5 volts, this powers multiple modules/chips.
"device active" signal: 3.3V when not active, GND/LOW when active. Active signal on average is about 2-4 minutes. If the signal is not active for 5 minutes, shut all power down.
I've seen circuits using microcontrollers, but I figured there had to be an easier and cheaper way. Appreciate any suggestions.
Vbat: battery voltage - 4.5 volts
Vout: Can go as low a 3.5 volts, this powers multiple modules/chips.
"device active" signal: 3.3V when not active, GND/LOW when active. Active signal on average is about 2-4 minutes. If the signal is not active for 5 minutes, shut all power down.
I've seen circuits using microcontrollers, but I figured there had to be an easier and cheaper way. Appreciate any suggestions.