3.7 V LI-ION Battery Charger

[panneerrajan]

Hi,
I have 3.7V /2100mAh Li-Ion Battery and have 5V/2A DC Adapter. I Need basic charging ciruit. The maximum charging VOLTAGE IS 4.3v

 

[kam1787]

http://www.ti.com/lit/an/snva520/snva520.pdf

http://cds.linear.com/docs/en/design-note/dn188f.pdf

http://www.instructables.com/id/USB-Li-ion-battery-charger/

 

[Externet]

Another way to do it is first measure the precise voltage outputted by your '5V' supply.
If around 4.9V better; if about 5.1V, not good.

Connect a selected 0.7V drop Si rectifier to the cell
(+4.9V)-------------|>|-----------------Cell (+)
That will drop voltage to 4.3V for charging. Measure cell voltage during charging, must not exceed the maximum.

Or, use a linear adjustable voltage regulator precisely set at ~4.25V.

 

[Audioguru]

Your Lithium battery cell will probably explode or catch on fire if you use a Mickey Mouse charging circuit. Use a proper Lithium battery charger IC instead.

 

[kam1787]

Your Lithium battery cell will probably explode or catch on fire if you use a Mickey Mouse charging circuit. Use a proper Lithium battery charger IC instead.

for a circuit look at https://www.linear.com/product/LTC4054-4.2