0
\$\begingroup\$

I recently purchased two L293D H-bridge Motor Controller from Adafruit (data sheet here), but after reading that the controller could only output a max of 600mA for a short time, I realized I had a problem. Due to the constraints of the Arduino that would be driving it, I can only get 600mA anyways, so I figured that I would need to use a DC-to-DC Step Up Converter to boost the voltage (therefore current) to run motors. However, I was worried that increasing the voltage after passing through the IC might damage it, and although I doubt it, better safe than sorry. Being two bucks a pop, would increasing the voltage after leaving the H-bridge, i.e., between the IC and the motors, damage the IC?

Forgive me if this is bad question, but I'm relatively new to electronics. :)

\$\endgroup\$
  • 1
    \$\begingroup\$ "so I figured that I would need to use a DC-to-DC Step Up Converter to boost the voltage (therefore current)" - You might want to check that assumption. A DC-DC converter can only put out less power than you put in. If you raise the voltage the current available will be less than the input current. Maybe you are talking about using a DC-DC converter from some source that can supply more current, but it's not clear from your question. \$\endgroup\$ – John D Jan 27 '16 at 23:36
  • \$\begingroup\$ A DC-DC converter can't create power from nothing. If it steps up the voltage, the current available is reduced. If the motors try to draw more current than it can supply, its voltage will drop. There is NO MAGIC, power can be wasted as heat, further reducing the power available. Calculate the power the motors need, and preferably post a link to the motors datasheet. It is likely that an L293D is the wrong place to start. \$\endgroup\$ – gbulmer Jan 28 '16 at 0:25
  • \$\begingroup\$ These motors are from an old drone(I think its this one), and the original battery used 3.7V and 500maH. This is the motor Sorry, I couldn't find datasheets \$\endgroup\$ – Enthurzan Jan 28 '16 at 1:08
1
\$\begingroup\$

The power (voltage times current) into a DC-DC converter is equal to the power out, plus a bit for inefficiencies and losses, so placing a DC-DC voltage step-up converter either between the Arduino and L293D, or between the L293D and the motors will increase the current drawn from the Arduino.

A DC-DC converter cannot create power - it can only get power from its input, and pass most of that power to its output.

\$\endgroup\$
  • \$\begingroup\$ So if I added a 1.5 V 2000mAh battery and my total of four motors drew a max of 4 amps, there's no way I could get that without increasing the size of the battery? \$\endgroup\$ – Enthurzan Jan 27 '16 at 23:42
  • 1
    \$\begingroup\$ Peter - Maybe the answer might read more clearly if it said something like "power (voltage times current) into a DC-DC converter is greater than the power out, some power is wasted because of inefficiencies and losses". Just a thought. \$\endgroup\$ – gbulmer Jan 28 '16 at 0:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.