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Single cell lipo protection circuit with replaceable battery design help

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vis321:
Hello,

I am currently working on a portable project which used a single cell lipo.

Without giving too much away, it's simple device that controls a few high power leds controlled though a esp32(via mosfets of course).

I need to implement battery protection circuit from over discharge and potential short circuit.

My battery is a tiny 3.8v LiHV (300 mah 45c), tested works fine.

I am boosting it to 5v via a TI tps61022rwur, that's all good, my device pulls MAX 3 ish amps for no more then 1-3 seconds (flash led).

I had a few issues when the battery gets low(empty), in software that I wrote for the esp, its measure the battery voltage and is supposed to shutdown the MCU when it gets low, still had issues when it was low battery. Instead I want to also implement a dedicated IC.

I came across a Ti BQ29700EVM-610 Eval board which uses a BQ29700 chip, the eval board work perfect for my application short circuit and UV protection work perfect. Was just going to copy the dev board schematic with same parts.

MAIN POINT:
Issues I ran into which was only mentioned on one page on the TI form and only on page 16, that unless that chip sees a charger first or V- is shorted to VSS temporarily it wont power on when I swap out a battery.... (for the first time when the chip gets powered).

Datasheet, http://www.ti.com/lit/ds/symlink/bq2970.pdf
Eval board datasheet, http://www.ti.com/lit/ug/sluuaz3/sluuaz3.pdf

That's no good for my application when switching batteries out.

Is there another chip someone can recommend for my power requirements? another idea I thought was to implement a one shot timer with a 555 that would briefly toggle the protection chip on (but it would need to work down to 3v...), am I going the wrong way about this?

If  V- is shorted to VSS the circuit works but then the protection does not kick in (must be in always reset mode)....

Marco:
Can't you just put a 100K resistor across the protection FETs?

amyk:
A standard DW01 circuit may suit your application.

vis321:
amyk, I would need it work work upto 4.35v lipo cells as we are using LiHV which can be charger to higher to 4.35v instead of regular 4.2v lipos.

Marco. do you mean across the gate of Q1 mosfet? This is the schematic of the dev board I am using, I did try a 100k ohm from TP4/Q1 gate/DOUT to BATT+ which of course did enable to output/ but that would disable all the protection from the output.


What if I was to implement a LMC555 as a one shot timer to trigger the protection on and the LMC555 would be low current enough not to kill the lipo as it would work with lower voltages ? thoughts?

amyk:
https://www.ic-fortune.com/upload/Download/DW01x-DS-17_EN_53550.pdf

They make a DW01F which is the 4.35v version.

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