I'm trying to power the LN298 motor driver in order to use a 12V linear actuator. This motor driver comes with a 5V voltage regulator, so you can power a microcontroller with one power supply. The problem is that there is a 2V drop (if I supply 12V to the motor driver, only 10V is sent to the linear actuator) which makes the actuator move slower than I want it to move.

If I supply more than 12 V to the motor driver (rated for much more than 12V) the voltage regulator shuts off, so now I need another way to power my microcontroller.

I have looked into other voltage regulators, but I assume a voltage drop from 14V to 5V might create a lot of heat. I am currently learning about SEPICs and trying to find some that work for my application, which seems like the best solution I can come up with. Are there any better solutions out there?

Thank you so much!

Edit: The microcontroller I'm using is an Arduino Nano 33 BLE and I suspect the current draw to be around 25-100mA.

  • 2
    \$\begingroup\$ "I have looked into other voltage regulators but I assume a voltage drop from 14V to 5V might create a lot of heat.". For a linear regulator, that depends on the amount of current passing trough. If the microcontroller (couple mA tops) is all that is powered by the regulator then it won't dissipate much power at all. \$\endgroup\$ – Unimportant Dec 27 '20 at 0:10
  • \$\begingroup\$ You need to specify the amount of current you need at 5V. \$\endgroup\$ – Elliot Alderson Dec 27 '20 at 0:37
  • \$\begingroup\$ Yep. Specify load current, and if it's enough to care, configure a switched supply instead of a linear supply. \$\endgroup\$ – Reinderien Dec 27 '20 at 1:41
  • \$\begingroup\$ Thank you for these quick answers! I suspect the current draw for the Arduino Nano would be around 20-100mA. I'll try a usual 5V voltage regulator and see how hot it gets. Note that nano has a built in 5V to 3.3V regulator. \$\endgroup\$ – Ishaan Kohli Dec 27 '20 at 1:50
  • \$\begingroup\$ At 100mA a standard 7805 should be fine with a small heat sink. But when you can get a switch-mode DC/DC converter for a few $ on eBay... ebay.com/itm/… \$\endgroup\$ – Bruce Abbott Dec 27 '20 at 4:19

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