Please explain to me how this device uses PWM to limit current

JoeN:

Chagrin:
They're based on the PT4115 driver

Truly an interesting part. Just ordered a few. Not the modules, just the ICs. Too bad they require a high current 68uH inductor, otherwise it would have been actually cheap.

I will play with these when the ship it is on makes port.

Hey, I got these parts a few days ago finally. It took a vendor longer than usual to send the diodes. Thanks for the suggestion. The test rig so far is linked below.

Here is how it performs at 10V:

.25A into the blue LED.
.25A into the green LED.
.60A into the red LED!
.10A into a short. (magic!)
.16A into a 1 ohm resistor.
.21A into a 2 ohm resistor.
.25A into a 3 ohm resistor.
.36A into a 5 ohm resistor.
.50A into a 10 ohm resistor.

Current measured is total from the power supply, not through the load, so obviously the load is not getting all of this but is likely getting 90%+ based on what the datasheet says.

Does this sound right?