H-Bridge motor control confusion....

Dec 18, 2006 3 Replies

I'm trying to build an H-bridge circuit to control a 12V DC, 2.5A motor from the DAC (0v~5v) output of an Atmel micro controller. I've looked at lots of designs of h-bridge, even tried doing some examples in Crocodile Technology. But things just don`t seem to work...



Can anyone help... open to any suggestions. I`m not thinking of trying a L298, but not 100% convinced!



Most H-bridge circuits are not driven with an analog signal. You would normally use a PWM drive to control your bridge. Have never used the L298 , but I'm sure you will need a "digital" , ie high and low signals to drive it. Does your micro have PWM outputs at all. Many do these days.Driving a motor with a linear controller is going to result in quite a lot of heat as well !!

You should decide on one approach or the other. H-bridges assume you are doing PWM. This is little or no reason to do the analog route for motor controllers lately.

Luhan

What exactly are you attempting to do with the motor? If you just want to turn it on and off and be able to drive in either direction, then a device such as the L298 will enable you to do that, accepting TTL level logic inputs and containing the necessary internal circuitry to generate the high side drive.

If you want progressive control of the motor, you will either need to implement a PWM system, or use a different output drive circuit that facilitates linear control. If you do require progressive motor control, you will almost certainly also require some feedback mechanism, unless your application is sufficiently crude that you can do it open loop.

T If it\'s not broken, don\'t fix it.

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