I'm using this particular motor driver IC to supply bi-directional current to a magnetic torque rod. I intend to control the Input A & B pins with my arduino uno, by using the PWM pins and varying the duty cycle. I also powered the IC with my arduino board and obviously got laughed at by my friends, I didn't know that arduino uno boards could only supply a maximum of around 200mA of current. So I'd like to ask:

  1. I am planning to power the IC with a DC power supply this time, I plan to give it a Vcc of 5V, how much source current should I supply to this IC?

  2. On the datasheet, I am not sure what the Sa and Sb (pins 1 and 4) pins are, the datasheet says they are driver output returns, but I have no idea what that means.



1 Answer 1


A 1 Amp supply would be appropriate for the chip. For the overall system, ... that depends on the "magnetic torque rod" and how you are driving it (on/off or PWM) you haven't told us anything about that.

You can simply connect the "Return" pins to ground.

Their purpose is to allow you to connect them to ground with a low value resistor (0.01 to 0.1 ohm) - then the voltage across that resistor tells you the actual current supplied to the load.

If you don't need to measure the current, then just connect them to ground.

  • \$\begingroup\$ Ah, if I go over one amp, would the chip blow? It takes at least 3 days to ship these chips over so I don't wanna waste them. Also, how does the voltage across the low value resistors at the return pins specify the current supplied to the load? I=V/R? \$\endgroup\$
    – John
    Oct 18, 2016 at 13:33
  • \$\begingroup\$ I'll edit the post and add more info on how I'm planning to control the torque rod. Sorry for the lack of info \$\endgroup\$
    – John
    Oct 18, 2016 at 13:33
  • \$\begingroup\$ yes - via Ohm's Law... \$\endgroup\$
    – user16324
    Oct 18, 2016 at 13:42

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