I have a project that has as 3W (using 500mA) Led and an I2C sensor at the end of a cable, and I need 6 wires for it. (4 to the I2C sensor) and 2 for the led.

I’m using the PT4115 CC led driver CI, but LED- is not GND, so I need two wires from the driver to the led at the end of the cable.

But I want to use a 5 wire cable, to use standard micro USB 5 pin connectors to connect this cable to the control box.

I’m searching for another led driver PWM capable IC that has a common GND at the led cathode, so I can share the same GND pin I use for I2c, but so far no luck...

Does anyone know of any SOP pwm capable led driver ic for a 3W led that has a commom gnd?

Or a way to get around this, in a power efficient way?

My Vin for the led driver is a 7.4V battery, and an attiny85 at 5V controls it’s pwm and the i2c sensor (proximity sensor).

I actually did find and tested a CN5711 IC (but in a separate module, not in my circuit) that has a common GND, but it heats a lot at 500-600mA...

The PT4115 with the proper inductor stays cool with no need for heatsinks... my enclosure space is limited in hight, so a heatsink is a problem if needed...


  • \$\begingroup\$ Part "shopping" questions are off topic, and asking if a part to purchase exists is exactly that. Likely these are unusual as low-side switching is preferred. Realistically, abusing a USB connector for this is a bad idea because someone will forget and connect something standard USB, releasing the magic smoke. You'll also have trouble buying 5-wire micro USB cords, and hand assembling the plugs on cable will be hard to do robustly. \$\endgroup\$ – Chris Stratton Sep 6 '20 at 13:47
  • \$\begingroup\$ @ChrisStratton I'm sorry. I didn't know it wasn't allowed for parts advices. But it could be an alternative circuit, if possible,with pwm input. I'm actually using an 8pin Mini USB connector (those found in Nikon data cables) for this, so no problems in connecting an USB "normal" plug in it by accident. But I wanted to get to 5 wires in total because also I'd like to test some magnet pogo connectors. And the max number of magnetic pins I found so far, for a ready available male cable and female connector is 5 pins... \$\endgroup\$ – Rodrigo Sep 9 '20 at 12:35

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