PinePhone (Pro) Battery Charger Teardown

PinePhone Battery Charger

I recently picked up this little battery charger made specifically for the Samsung J7 battery used by the PinePhone (Pro). It features:

• A single USB-C port
• Red/green status LEDs

Yeah that’s about it. Very simple, but that’s good.

Seems to work just fine, but for shits and giggles I decided to break it open. I figured maybe this could be useful to someone making their own charger.

Outside

For lack of better photos, here’s the original product picture from Pine64:

PCB

This is the very simple PCB inside. It’s based around the MICRONE ME4057DSPG-N IC.

Here is a (somewhat poorly) translated copy of the datasheet.

The charging logic for this IC is as follows:

• Under 2.9V, trickle charge at ¹/₁₀ I_BAT
• CC to 4.35V
• CV at 4.35 until current falls to ¹/₁₀ I_BAT
• Off, showing (Green) STBY LED
• If voltage drops to 4.16V, charging is resumed from the CC stage

Schematic

From the datasheet, I_BAT = 1100/R_PROG, meaning the battery charging current is approx. 790mA or 0.26C of the original 3000mAh battery that comes with the PinePhone (Pro), and trickle & cutoff current is about 79mA.