Electronics > Beginners
1 button power on\off + UI button
ignislion:
Well I havent done yet! =)
First of all, I am very curious why I ever have seen only p-MOSFET, "positive side" power on schemes? N-mosfets have better performance and it seems to me that there is not so must difference on which side of load to operate.
I kinda draw some schema and going to test it on weekend. Maybe you can say to me why I am wrong before I going to waste time.
Another question is it ok to just connect external 5v power directly to the controller when the battery is charging?? Like in screenshot. I need to use LDO in between but overall is it OK to connect 5v after step-up? it has diode anyway so i thought it is going to work.
Here is all the schema I have at the time: https://easyeda.com/ignisilion/weather
ignislion:
As for the power switching circuit here is on what I am stopped:
Zero999:
In order for an N-MOSFET to switch the positive side, its gate voltage needs to be above its source voltage, which is connected to the load. If there's no higher voltage in the circuit, then it would need to be generated using some kind of boost converter, which is costly and increases complexity. It's just cheaper to use a P-MOSFET or an N-MOSFET and switch the negative side.
This sounds similar to another recent thread. Refer to the link below. It might be relevant.
https://www.eevblog.com/forum/beginners/push-button-power-circuit-for-arduino-trying-to-modify-it-for-12v-input/
ignislion:
Sorry, my message was badly composed. The stuff with VGS +/- is understood. My question was why i have seen so much pchannel high side switches other than nchannel low side? Because n mosfets have better rds on. It looks like i canr see something more
rstofer:
Probably because we don't want any voltage drop when pulling to ground.
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