24V DC motor using a ULN2803A

[deperkin]

uln2803a circuit

I have attempted to use both a L6201 and an L6203 to drive a 24V DC motor for a project i am running out of time on...
Both have successfully let out all of the blue smoke trapped inside...
The L6201 is rated at 1.5A continuous current and the L6203 is rated at 4A...
I have checked the wiring and cannot seem to figure out why this motor (of which i cannot seem to find any good specs on) has burned both of these full bridges.
I have measured the current and only seem to see about 0.7A continuously while driving the motor.
Would a ULN2803A darlington help with this problem ???
any suggestions on how i can wire this up with a full bridge ???

THank you for all your help!

BR
deperkin

 

[pauloynski]

uln2803a

Have you placed a snubber network in parallel with th motor? Please pos your circuit.

 

[deperkin]

uln2803a motor

I read the datasheet closer and it does not look like the Darlington will handle the current anyways.
I am not sure why i keep smoking the L6203's...
Here is a schematic of how i have this wired right now...(see attached)

Also, the power supply (24V) says that the output is only 1A.


Thanks and best regards,

Deperkin

 

[pauloynski]

uln2803a examples

Take a look at this **broken link removed**

 

[deperkin]

uln2803a example

I have used the same wiring on the L6203 as well.
No snubber network, no...

i am not familiar with these... any chance you could sketch what you mean?
i will look it up now.

Thank you very much!

 

[pauloynski]

24v dc motor

The snubber is the RC circuit you´ll find placed in parallel with the motor. It is clearly shown in the examples you´ll find in the L8201-03 datasheet.

Added after 4 minutes:

Also, remember that under heavy load the current will increase a lot.

 

[deperkin]

microcontroller dc motor l6203

I read this, actually just before you posted the like... great source.
The only issue i have with this is that he is showing a 5.6A peak, when the chip being used in his example is rated at 5A peak.

I will have to try some calculations...
He does mention that the actual is usually much lower then the calculated.

I have to be careful now since i only have 1 more L6203 left and these are $13 each!!! my wife is getting, well, you can imagine...

In this example does the Resistor also need a high current rating or would any lil resistor work for this part of the circuit.

i think i only have some that go up to 1W...

thanks again! BIG help!

 

[pauloynski]

dc motor 45v/4a

The resistor is used only to charge and discharge the capacitor during comutations. Without making any calculation, a 1W type should be enough.

Added after 3 minutes:

OOOOOOps!! The example I´ve sent you shows a 2,3W resistor.

 

[deperkin]

l6203 dc motor microcontroller

Thank you once again!

looking at the datasheet again i see the snubber with a 10-ohm and 22-nf, which would limit the current peaks more...

You have been a mighty big help!

 

[pauloynski]

uln2803 dc motor

When switching inductive loads (like a motor, solenoid or relay) allways remember that you can´t stop current from flowing instantaneously. A path is necessary for it to change smoothly, otherwise it will react with large spikes (refer to the Maxwell´s laws).