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Topic: MCP4261 burnt after power on a little while by MEGA 2560 (Read 466 times) previous topic - next topic

laoadam

Tested a MCP4261 by MEGA2560, the MCP became hot after half hour, what's wrong?


MarkT

How can we follow that diagram?  You have two completely different pin outs in each of the diagrams.  Please try to draw comprehensible circuits, rather than make us
redraw them individually to figure out what's what!
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

laoadam

How can we follow that diagram?  You have two completely different pin outs in each of the diagrams.  Please try to draw comprehensible circuits, rather than make us
redraw them individually to figure out what's what!

Thank you MarkT,

I redraw and attached the picture. I don't know how to delete the old one. 

Southpark

Tested a MCP4261 by MEGA2560, the MCP became hot after half hour, what's wrong?
It will likely be helpful to describe the situation with more detail. Sure --- it got hot after half an hour. But it will be helpful for everybody to know the conditions of operation.

For example ----- was the system doing exactly the same thing as when you first started it up?

Or the system was performing some particular operations during that half an hour.

laoadam


WattsThat

If it kind of sort of works and it gets hot, you're drawing too much current through the wiper(s).

Without seeing what both pots are doing, your guess is better than any one else's since only you can see what they are connected to.
Vacuum tube guy in a solid state world

laoadam

If it kind of sort of works and it gets hot, you're drawing too much current through the wiper(s).

Without seeing what both pots are doing, your guess is better than any one else's since only you can see what they are connected to.
Do you know how to reset the MCP4261?

JCA79B

Hmmm, the 'ol carbide cranium. How   much   current   are   you   drawing   through   the   part   ?
The most intelligent people in the world are the ones who don't think of themselves as the most intelligent person in the world.

laoadam

Hmmm, the 'ol carbide cranium. How   much   current   are   you   drawing   through   the   part   ?
Didn't measure, the load is 4.7K + LED.

Southpark

Didn't measure, the load is 4.7K + LED.
It looks like it's hard for you to get a proper answer here until you show the full details. Your images that you posted showed none of what you mentioned above. So nobody can properly help you unless you first help yourself to describe the situation (the actual circuitry you used) with adequate detail - such as what you had done, and what code was used, and whether the system was actually doing what you wanted it to do for say 25 minutes (remained cool) ..... and then all of a sudden got hot. At the moment, you haven't provided enough information that allows anybody to trace your issue in an efficient way.

BJHenry

Didn't measure, the load is 4.7K + LED.
The maximum current through the wiper is 2.5mA, so the LED is likely drawing too much.

Southpark

The maximum current through the wiper is 2.5mA, so the LED is likely drawing too much.
BJ ..... is that a 5V system? Not sure what their connection is ... but 4.7 kohm across a bare 5V system would give around 1 milliamp? Still don't know what their set up is. Was just asking only.

BJHenry

BJ ..... is that a 5V system? Not sure what their connection is ... but 4.7 kohm across a bare 5V system would give around 1 milliamp? Still don't know what their set up is. Was just asking only.
That's a good point. Max VDD is +7V. I had assumed that the LED wouldn't be working with so little current and so the OP must have gotten the resistor value wrong.

TomGeorge

Hi,

Can you please post a copy of your complete circuit, in CAD or a picture of a hand drawn circuit in jpg, png?


What are you connecting the digital pot too?
Does it have more than 5V on it from the circuit you are trying to control?


Thanks.. Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

Southpark

That's a good point. Max VDD is +7V. I had assumed that the LED wouldn't be working with so little current and so the OP must have gotten the resistor value wrong.
Totally agree with you BJ.

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