I'm currently working on a project and have an underlying problem.
I want a motor driver (TB66121FNG) with an Arduino
address and so 2 DC motors (turn in both directions).
I had a circuit board made for this. When I tried this one out today, everything worked fine. However, when I unplugged the USB cable from the Arduino in order to operate the circuit via a 5V power supply, the motors stopped rotating. They just twitched slightly, as if they were barely getting any electricity.
I really connected all GROUNDs on the circuit board. And all components are also supplied with sufficient voltage (Arduino via Vin with 5V), VM from TB66121FNG also with 5V. The motors are also designed for 5V. Why does the circuit only work when it is connected to the laptop?
You will find my circuit in the appendix
Kind regards
Arduino over Vin with 5V
It's already a mistake… The Vin has a fixed voltage regulator behind the pine input and needs at least 7V so that the fixed voltage regulator can reliably deliver 5V. At 5V, maybe 3-4V will come out… And everything that is on the 5V pin will only get this 3-4V…