- CC CV regulation
- Multiple settings
- USB C power delivery 20v
- Reverse polarity battery protection
IP2721 negotiates voltage set by J2 (short 20v open 15v) and outputs it to VBUS_PD
Typycal LM358 based CC CV regulation circuit
| CC | CV |
|---|---|
 |
 |
Battery protection circuit works as SR latch with one of latching elements being P-MOS that outputs voltage to battery. One downside to using this schematic is that charger needs to be powered down in order to "delatch" protection circuit, otherwise it may not work if battery had been disconected and reconnected again. This issue will be fixed in upcomming REV-B.
Power on state. Circuit is delatched.
Connected battery starts to turn on transistor that turns on photocoupler. Circuit latches and starts charging battery, given it can provide 20ma of current and it sits above 1.5v.
Intended use is keychain charger to charge for example car battery form powerbank that is capable of PD output.
Or li-ion / li-pol cell (using different settings) for various use cases.
It is definitely better to have one of those boards lying arround in car or in backpack than not even tho it does not offer best charging performance.
CERN-OHL-P (CERN Open Hardware Licence Version 2 - Permissive)