Bipolar Stepper Motor Driver heat problem

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nick703

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hello friends i want to create bipolar stepper motor driver.

then i have to choose pin compatible version of ic like A3979 and drv8818 from texas instruments.

now please give me a some hint how to design my pcb to remove heat of ic when current is exceed 2A.

then how to create surface area to remove heat of SSOP-28 pin package. is that required more hole or required more copper plane to remove heat please guide me .

below is the create simple top layer part in ic image.


please help me how to remove heat then do not required any heat sink . is that possible with top and bottom layer of pcb ?
 

Hi,

read the datasheet.
There is a section called "thermal information"
And there is a example board layout drawing.

Remove heat: You can´t change the disspated power, so you have to transmit the temperature on a large area of your PCB. Copper has a good thermal conductivity. Use thick copper on your PCB.
Use as much copper as you can. Maybe you can´t avoid an extra heatsink.

Hope this helps
Klaus
 

Check the ICs power dissipation & using thermal resistance (Theta ja), calculate the temperature raise. Add the temperature raise with ambient temperature & see it is not exceeding the maximum junction temperature of the IC. According to the thermal margin you get, you can decide whether a heat sink is necessary or not.
 

ok friends now i have a question A3977 and A3979 is pin compatible ok
now below is my circuit diagram of A3977 and i have a same configuration in A3979 . but this time my circuit doesn't work ? is that any additional setting required ? please suggest me .

and my A3977 based driver working completely but A3979 based driver not working why ? every thing diagram pcb and programming same but my this driver not working is that any component required to change ?
and also my A3977 is a PLCC 44 pin version and A3979 is TSSOP 28 pin package version ..

please kind me suggest best solution . in datasheet every thing same content of A3979 and A3977.
 

i have a further testing my board and i have found some solution when my stepper motor speed increase that time stepper motor miss the pulse and motor vibrate but in A3977 board i have a same speed applied but not any missing the pulse . so how i would to change any component of my stepper board please suggest me bro!!!!!
 

NICK did you fix thermal cooling problem with large ( >4sq in) copper heat sink to substrate of IC? or forced air?

What is purpose of Opto if In, Out share a common ground? Nothing?? convert bipolar pulses to unipolar?

Can you compare Schmitt trigger output signals?
 
hello Sunnyskyguy thanks for reply ,

yes i have large ground plane on TOP and BOTTOM part of my PCB to reduce heat . and now i have also use heat sink for ic cooling .
actually opto - coupler ic is the better solution instead of giving direct pulse . and yes this opto coupler ic also working in my A3977 board .
but this time only problem is motor some time not rotate as per my command .
 

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