need help with motor driver ICs

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abbas14

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hello everyone,
here is another question..
most of us must be aware of the well known motor driver IC L293D. it can drive a dc motor both unidirectionally as well as bidirectionally.
for unidirectional motion, only one logic input is required, whereas for bidirectional motion, two logic inputs are required. for bidirectional motion, it is quite obvious that one logic input has to be the logically inverted version of the second logic input (or vice versa). if both the inputs are logically same, the motor wouldn't simply run.
now, for driving a motor bidirectionally using only a single logic input (in order to save the microcontroller or microprocessor pins), a logical inverter gate can be used and two logic inputs can be generated from a single logic input. this is quite easy. but this also has a disadvantage of requiring an external hardware, thereby making the system bulky.
now, what i am trying to ask is isn't there any such ICs meant specifically for the purpose of driving a dc motor bidirectionally?? that is, that would have a NOT gate inbuilt into a single package, and would require only a single logic input for bidirectional motion, say 1 for FORWARD and 0 for BACKWARD???

can anyone help me with that???
 

look my friend abbas , donot look because you will not find and i will tell you why . because usually these drivers make variable speed control so they take PWM signal (which constantly switched ON and OFF) and it makes no sense to use only 1 pin for both directions , u need 1pin for direction (1 for 0 back) and 1pin for speed (PWM) . if no speed adjustment is required use relays instead .

I want to help you , so i will suggest something for you , if you want to save an IC (NOT gate) , make your own inverter using simply a transistor and resistor :**broken link removed**

1 last thing if you are designing this inverter and using high freqeuncy PWM make sure the npn transistor used is fast enough .

hope that helps

take care and welcome to edaboard
 


thank you very much for your help sir..
well, you have a point though. but relays will create a large EM disturbance and will interfere with the sensor readings, leading to sensor readings which are not correct. also they will acquire a lot of space and weight.
also, its not about saving on an IC, its about saving on size and weight. i intend to design the controlling board as compact and light weight as possible...
 

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