if you charge lipo batteries incorrectly there is a substantial fire risk, drawing power from the charging cct can lead to improper charging.
you might like this
http://ww1.microchip.com/downloads/e...tes/01149c.pdf
if you charge lipo batteries incorrectly there is a substantial fire risk, drawing power from the charging cct can lead to improper charging.
you might like this
http://ww1.microchip.com/downloads/e...tes/01149c.pdf
Warning I'm not a teacher
Thanks Richard,
That was really quick!!!
Yup, I think this is exactly what I'm looking for.
I should have thought about these chips since I sometimes use MCP73831 ones.
Thanks a lot again
Roger
"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
Thanks Sayser,
Unfortunately, 3.2V will be too low - anyway, thanks for the Li-FePo4 advice
BTW, going back to AN1149 and the choice of the P-Channel MOSFET, as I don't know if a FDN360P will do the job?
Any clue?
Roger
Consider this one: DMP3099L-7
I have my own charging circuit controlled by PIC with FVR.
Measure batt voltage by adc read on FVR to calculate the batt voltage.
If over 4.25V then cut the charge; if lower than 2.75V then suspend all operations.
All done within the pic.
You need an ppnTR-P-ch charging circuit; very simple.
"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
FVR is not at all accurate, so that 4.25... I doubt you are safe.
Ioannis
Last edited by Ioannis; - 19th May 2020 at 09:58.
Why is not not accurate?
I get 1.024V with 1x output.
And if the Vdd is 2,5V I still have 1.024V at my FVR output. I never encountered an accuracy issue.
But, if you have a high freq circuity on the same pcb, or even if your PWM module is running, then I agree, FVR can be disrupted.
Also, here is a simple circuit diagram for NPN-PCH charging. Assuming you are not charging the batt with high amps, LM317 would do the job. If not, change LM317 to a switching circuit to have higher efficiency and lower heat.
"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
Because according to Electrical Specs, the FVR may be from -8% to +6% for example on 16F1827.
I would not trust this to charge a LiPo battery at all!
Ioannis
Roger, the minus Vgth is correct. Consider it a different visual angle!
In P-channel or PNP transistor the voltages are the opposite of the N-channel or NPN transistors. Means that the voltage og the gate in respect to the source is negative. The key to understand here is the term "in respect".
Ioannis
If I may ask further,
The "most important" value to take care off is the "Gate Threshold Voltage"; right?
It has to be as low as possible...but how low and why?
I thought RDSon value is very important too. But in this case, where the current is somehow small, is this less important in choosing the "right" MOSFET?
Roger
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