Anyone have a favorite push on hold off power circuit that they would like to share?
I’ve got a “home made” project I’d like to use a power button instead of a switch. I’ve got one to try out that I’ve used before, I’ll post it when I find the schematic. Wondering if anyone has any suggestions?
Looking at one of these potentially or something similar. Preferably not BGA…
This should work? The reset pin would theoretically have some leakage over the 10k resistor and through the controller hopefully it wouldn’t be substantial? I might be able to increase the values of the resistor as well.
Updated to include a diode on the reset line…
Wouldn’t this work?
I’m missing ground fill and test points but this is the power circuit including usb and battery charger.
Decent topology it’s 1 layer although no ground fill or pinouts… but that’s for tomorrow.
If real estate and parts count are a concern, you may wish to consider just using a simple 6 or 8 pin microcontroller for this. It would probably only require the MCU a MOSFET, a couple of resistors (and of course, the button).
There are many different ones available, with the ATtiny4 being just one example (not necessarily the best choice).
ATTINY4 Summary
An advantage of using a microcontroller is that you can have all sorts of button sequences. For instance, you could require the button to be held for a few seconds to initiate power on and power off, to prevent accidental activation. You could have reset require a double click (or whatever), again to prevent accidental activation.
You also have spare pins that could be used to control other things, based on different button sequences. Or, these pins could be used for entirely separate functions, such as a low battery sense, indication and power down, or even just an inverter gate if you need one.
Very interesting concept. This is only a few extra more components and they are all easy to source and cheaper still.
I can’t exactly think of a reason for the multiple button presses but I do like the idea. A battery supervisor is clever though. Not sure the complexity is what I’m going for though.
Here is the circuit I’ve got on the test board, I’m going to make a few of them and put them for sale in the store (if they work)
