Current Source Plug

The Current Source Plug is a small board based on the AP8803 chip to provide a constant current to two sets of power LEDs of 350 mA or 700 mA. The two I/O pins can be used to turn the LEDs on or off, and for dimming via PWM. This plug uses a very efficient switch-down supply “buck” design - instead of converting surplus voltage to heat, as resistors would do.

Theoretically, each of the two channels can drive up to 5 power LEDs of 3W each @ 700 mA, when powered by the maximum 30V. In practice, this may generate too much heat for this small board if used without an extra heat sink. The design goal was to support 1..2 LEDs of up to 3W on each channel from a 12V input voltage. Higher is probably possible if the LED supply voltage only exceeds the LED’s own forward voltage by a few volts.

The terminal blocks used on this plug are heavy duty and detachable and use a standard 0.2" grid (5.08 mm). The two outputs have separate connectors. Note that they do not share a common pin.


There is a solder jumper for each channel, which can be shorted to increase the current output from 350 mA to 700 mA:

Header Pinouts

Design Info

Dimensions: 21.1 x 34.0 mm
CadSoft EAGLE design files: see below.
This plug can be operated at 5V as well as 3.3V.

This board uses the conventions of a JeePlug and can be used with the ports on a JeeNode. It can also be used with other boards and MCU’s, if you hook it up properly and adapt the interface code for it.

How to Get It

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