Controlling a RS-360SH Motor Using a H-Bridge

Dear all,

I am currently trying to control a montor using my arduino and a h bridge. The problem I face is that the h bridge gets very hot and I think it is not safe to operate under such a condition. I am also pretty sure that I am doing some things wrong, but due to lack of experience, I would be very glad if someone could provide feedback/advice on my setup. To make things easier, I provide a sketch of my circuit and technical data of the components used.

Components used:
I use an external power supply which delivers 12V DC 1.4A. The h bridge is a L293D from Texas Instruments [1]. The motor I use is a RS360-SH [2]

Sketch of my setup:
The sketch attached to this post shows a motor M connected to the left part of the L293D. The power supply is used to power the L293D, the motor (via L293D) and the arduino. DP1 and DP2 are digital pins which I set to a fix value. This seems to work OK. the motor runs in one or the another direction.

My Questions:

  • Is it possible that the heat comes from the voltage applied to pin 16 of the L293D (VCC_1). I have seen in the datasheet, that the recommended voltage for pin 16 should be within a range of 4.5 - 7 V. In my case, 12 V are applied. Do I need to use a voltage regulator in this case? Is it better to apply a voltage of 5V or 7V to the circuit? Applying a higher voltage also means more current, which also means more heat? Is that correct?
  • I also think that the L293D is somewhat underdimensioned for my motor. The data sheet mentions a max. current of 600mA per channel, but my motor draws 2.2 - 4.7A. Is this another factor, which makes the L293 very hot? If yes, could you recommend a better h bridge for my motor? Actually I would like to avoid buying a full motor shield, because of costs. If possible I would like to simply use a h bridge.

As a side note: the motor will be not be running constantly. I will only use it to pump some water. This takes perhaps 5-10 seconds, once a day.

Thank you very much for your help. I really appreciate your help. If you need more information, please let me know.

Best regards,

External Links:

circuit.pdf (726 KB)

Vss is the logic supply voltage and should be the same as the Arduino, 5V, if connected to an Arduino operating at 5V. This should guarantee reliable recognition of the incoming logic signals.

The heat generated in the device is either just the output driver losses (they are very lossy), or could be due to operating the device with a motor attached, Vss (pin 16) powered but Vs (pin 8) unpowered. This should never be done as is causes internal protection components to take power from the logic supply direct to the motor.

This H-bridge chip is rated for a maximum of 0.6A, and peak pulses below 1.2A - if your motor takes 1.2A or more you are over-driving the chip and may damage it, Even if you only take 0.6A it will overheat if not properly cooled.

You should find out the stall current rating of your motor(s).