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I want to build a tiny obstacle avoiding robot using a 3v coreless DC motor. I've been using L293D to control 5V motors and up, but I can't seem to find a motor controller that works with motors below 5V anywhere. I also have 3V Canon two-step motors, but I would much rather use the 3v coreless DC motor if possible:

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Do such a small motor-controllers exist or do I need to looking for a different solution? All I'm trying to do is have some kind of tiny component that will let me control both (or at least one) of the motors in both directions.

Normally I could use L293D, but it requires 5V inputs for the trigger pins as well, but my project will be using only 3.7v.

Thank you!

0x29a
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Normally I could use L293D, but it requires 5V inputs for the trigger pins as well, but my project will be using only 3.7v

The L293D has input logic levels of 2.3V for logic 1 so that shouldn't be a problem.

I want to build a tiny obstacle avoiding robot using a 3v coreless DC motor

The L293D is such an awful device that running it from 5V will probably only produce 3V at the motor terminals on light mechanical loads. If you read section 6.5 of the data sheet it tells you that with a motor current of 0.6 amps, the high voltage from the bridge will be Vcc2 - 1.4 V (3.6 volts typically) and the low output from the bridge will be +1.2 volts (typically) meaning that the voltage across the motor will be about 2.4 volts.

So if you want to use the L293D running from 5V (via a boost regulator from 3V to 5V) then you should be OK. Further information about L293D here

Or, use the DRV8836: -

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DRV8834 runs at 2.5 volts and can supply over 2 amps, whereas the 35 and 36 are limited to 1.5 amps.

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Andy aka
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  • Thank you very much for the answer! I can't accept it yet (time limit). I noticed that there are a lot of DRV8833 on ebay, but they're 1.5amps as well, but they come with the 'case'. Will the 0.5amps make a big difference? – 0x29a Oct 24 '16 at 10:02
  • oh maybe you just solved another problem of mine! I use L293D to control two 5V motors. For motors I feed it 7.4v and for triggers/enable pins I give it 5V, I don't have a multi-meter atm to measure output to the motors, but they seem kinda slow and the robot can barely drag it's own body (just two 3.7v li-ion batteries). Does that mean that my motors are actually not getting the full potential 5v? thank you! – 0x29a Oct 24 '16 at 10:02
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    1) "case"???? I don't know what that means - do you mean a heatsink is attached? Regards current, I can only say that they are capable of driving that much current and that current only passes if the motor demands that much current. 2) See the link in my answer for further reading on the L293D but they are pretty crappy and even with Vcc2 at 7.4 volts, under load the output will be below 5V across the motor. You can still up-vote I think!! – Andy aka Oct 24 '16 at 10:13
  • sorry, I mean they sell as a 'module' instead of the DRV8833 component itself, so it's a bit easier to attach to circuit board. – 0x29a Oct 24 '16 at 10:22