How to protect ?

Big Dog

Hello, it is my first post.

I am using·754410 motor driver ( 5v as logic supply, 12v as motor supply) to drive··two·12V , 300mA geared motor ( 100mA @ no load ), control with basic stamp

I have put them together as datasheet said, and put fairly large heatsink.
It worked few hours, then suddenly the motor speed went down for a minute ,·then ·the motor did not move at all.

I changed the 754410, the system worked again for days, then the same problem occured

What happened exactly? Any Idea how to prevent that to happen again ? Or it just the quality of the 754410 ( different batch , different quality )?

Thanks

allanlane5

You didn't mention if you have a 'snubber' diode across the motor. Without one, when you turn off the motor, the 754410 will get a reverse-biased voltage surge, which can destroy it.

Mike Green

1) Do you have the protective diodes as shown in the datasheet?

2) The device should not be failing based on your description. None of the parameters are anywhere near the device's limits. There must be something about your setup that you have not described. Check your wiring. Check the actual current drawn by the motors (roughly ... just to make sure it's not significantly higher at times). How warm does the heatsink get (roughly)? Post the actual schematic of your setup.

Big Dog

Thanks for your comments, guys
I did not put any diodes as protections, please recommend which diode type is suitable for my appication

Mike Green

Any power diode rated at 25V or more and 1A or more. A typical diode is the 1N4001 rated at 50V and 1A.

Big Dog

Okay, Thanks Mike [noparse]:)[/noparse]
Have a good day......