High Current (18v25CS) Drivers and V+ Supply Error

I made what seems to be a fundamentally incorrect assumption and I wonder if others have found out the hard way.

My project employs a high current 12vdc supply for a slow speed high torque motor. I read the tech details describing the hook-up and specs for the 18v25CS driver and thought that the small V+ on the logic side of the board was for a separate 5v supply since I did not see any regulator chip on the board for a digital 5v supply. So I am testing the driver with both a separate 5vdc and 12vdc supplies and finding that my Arduino (Moteino with FTDI USB adpater) is going bonkers (overvoltage). I then do the simple check of finding that small logic-side V+ pin and large V+ load side pad are one and the same !!!

I don’t know about anyone else but it would be nice to have pointed this out on the technical webpage. I am lucky that my Moteino V+ input can tolerate the overvoltage but I could have blow out my PC’s USB with the overvoltage.


I am sorry you had problems powering your motor driver. In general, you should expect pins with the same name to be connected to the same electrical node, and we express in multiple places on the 18v25 CS high-power motor driver product page that the V+ pin is the main motor power supply connection and that the smaller V+ pad on the logic side of the board allows access to monitor the motor’s power supply.

I am happy to hear that all of your components still seem to be functional; making connections based solely on assumptions is a very easy way to damage electronics like this!

- Jeremy