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Lipo circuit is working

A project log for ESP8266 (ESP-07/12) Dev Board

PCB for fast development with ESP-07 / ESP-12 with on board USB to Serial converter and on board lipo charge / protection circuit

alexAlex 05/30/2015 at 18:104 Comments

Just a quick Update: I soldered the lipo and switching regulator circuit (upper corner in picture) today. It works fine. Only minus is that i forget to make some load sharing circuit. So if charging the battery the esp itself also runs from the charge current.

Discussions

davedarko wrote 05/30/2015 at 19:03 point

The LM3671 is quite interesting! I googled around a bit to find something that is capable to convert LiPo voltages to 3.3V and only found a polulu module so far, the S7V8F3 https://www.pololu.com/product/2122

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davedarko wrote 05/30/2015 at 19:04 point

I was wondering at first, how you'd manage to run an ESP off of 4.2V safely...

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Alex wrote 05/30/2015 at 19:42 point

Yes the Version in the picture uses the LM3671 as step down for the battery voltage to 3.3V. But this is only one of two options. Instead also an AMS1117-3.3 (on the bottom of the PCB) can be used. but this is not very useful when powering from a battery because of the low efficiency. 

The module from pololu should be be also suitable in a similar case. A good way to find suitable voltage regulator ICs quickly is this small webtool from TI (http://www.ti.com/lsds/ti/analog/webench/overview.page). They do only list TI parts! 

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davedarko wrote 05/30/2015 at 19:52 point

The AMS1117-3.3 is only a drop-down and has a voltage dropout 1V - so LiPo is out of question there... you could use 2 of them or a 9V block. But I'm looking for a 3V - 4.2V to 3.3V thing ;) 

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