Mosfet choice

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loboris
Posts: 514
Joined: Wed Dec 21, 2016 7:40 pm

Re: Mosfet choice

Postby loboris » Thu Feb 15, 2018 8:58 am

Any of BSS123 will do.
The schematics looks ok. I would suggest adding a 10 - 100 nF capacitor to the ADC.

MCP1700 can provide max 250 mA, which may be insufficient for ESP32 when wifi is started.
Holtek's HT7833 can provide 500 mA (quiescent current of 4 uA) and could be a better choice, but it has a larger dropout voltage.
If using the the MCP1700 you should add 0.1 uF + 330 uF capacitor on the 3.3V near the ESP32 power pin, it should be sufficient to make it work.

You may also consider usin the LiFePO4 battery in which case no LDO is needed.

Azaelyus
Posts: 13
Joined: Tue Oct 24, 2017 7:38 pm

Re: Mosfet choice

Postby Azaelyus » Thu Feb 15, 2018 10:38 am

Im using 18650 http://lygte-info.dk/review/batteries20 ... %20UK.html

Thats why i want as low dropout as i can because the battery gives out about 3,5 v when it reaches 90% of its capacity. Thats why MCP1700 max 200 mV dropout is the best option for me.

Ok, i redraw my scheme and now it looks like this.

Image

Does it look better now?

EDIT: Cant find any suitable cap for me :( Any ideas? Should i use electrolytic?
Found this one: http://uk.farnell.com/murata/grm32er60j ... dp/1828817
Do u think 100 uF will be enough?

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