DC Motor Drive L293D

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christinescoms

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I used L293D to run Stepper motor and i did it with Bipolar Stepper Motor successfully... Then i came to know that is Dual H-Bridge Ic that can run DC motor in both directions... then i connected as like the diagram... logic input of 5V and motor supply of 12V with 7805 and 7812 regualtor respectively from 12V 5Ah battery... but the problem is the IC heating very hot within secods... I am using 12v 300mA DC Geadred Motor... but L293D can drive upto 600mA per channel and peak of 1.2A... but dont know what is the mistak i did... pls help me with this.. and also the motor runs only on Low input not on high and even when enable pin is not High... pls check my diagram and make me where i made mistake...

**broken link removed**

150RPM 12V DC motors with Gearbox
6mm shaft diameter with internal hole
125gm weight
Same size motor available in various rpm
2kgcm torque
No-load current = 60 mA(Max), Load current = 300 mA(Max
 
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thanks in advance for any help
 
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You need a L297 in conjunction with dual H-bridge that gives you the ability to set the current limit, the H-Bridge requires sense resistors.
A 10 turn pot with resistor is used from 6v to GND on pin 15 is used to set the limit in conjunction with the sense 1 & 2 inputs.
The L293 is more suited to DC brushed motors.


 
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christinescoms said:
pls check my diagram and make me where i made mistake..
Click to expand...

No diagram?
What connections and drive waveforms (and frequency) are you using?
For the L293, you need to generate the non-overlapped PWM signals.

Have a look at the Double BTS7960 modules you can get on ebay etc., or those ICs themselves. They include the non-overlap timing so only need a single drive signal per half bridge, and include current sense which can be configured with a single resistor.
 
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Just to add to rjenkinsgb comments, modern processors have PWMs that can be configured with
"dead band" timing, here ph1 and ph2 are setup with 12 clocks of non overlap timing. :




This is to prevent in H bridge one vertical leg both top and bottom switches on shorting
out power rail in system.




Regards, Dana.
 
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