2025-08-15 - reverse engineering of a garden dusk LED light

i recently came across a garden LED lamp, that's batter powered and self-charges via a solar panel… and it costed only 0.50€. that was interesting – how can you make something _that_ cheap and still make profit? and so i decided to take a look inside.

quick peek inside revealed there's really not much to it.

there are only 3 semiconductor parts: YX8051 LED driver, photovoltaic (PV) panel… and the LED itself. here's the schematics in KiCad.

it's basically copy-and-paste from the datasheet.

interestingly enough, the part that looks like a resistor is actually a conductor – the chip is acting as a boost-converter, too.

the way it operates is, when PV gets light, boost converter is off. up to 1.5V from the PV panel is then charging the battery. voltage on LED / conductor / chip junction is <1.5 there (conductor has ~6R of resistance for DC).

when PV panels gives under ~0.5V, boost converter kicks in, generating around 3V for the LED to start emitting light. it operates at 210kHz, at 50% PWM. enough to make it shine.

the design is therefor clearly using a dedicated silicon to pull all of it off. PCB is a trivial and 1-sided. BOM is minimal. a well optimized design. nevertheless i'm still flabbergasted it all fits into the 0.50€ budget – it's truly bonkers. happy times i guess… ;)