Maker Pro
Maker Pro

IC heating up!!

paddy

Sep 11, 2012
81
Joined
Sep 11, 2012
Messages
81
You still haven't given us a full and detailed introduction to your situation. In other words, tell us the FULL STORY. I can't ask the right questions because I don't know what to ask. You need to start from the beginning and explain the whole situation.

I'll try one more time to work from your partial information.

You said the board is new to you, and you found the problem during testing. Why are you testing these boards? Are you working for the company that manufactures them? Can you get a full schematic diagram? Why are there so many design errors on the board?

We have identified several design errors with this board:

1. 40106 pin 2 (output) fighting with the output from the 4071;
2. 40106 input pins for unused devices were not grounded;
3. 555 pin 7 should have a current limiting resistor;
4. 40106 pin 3 should have a current limiting resistor.

You have been patching the boards to fix these errors, right?

What is your role? Are you testing these boards as part of a production process?

You say with these corrections the heating is reduced but is "not completely resolved". How hot are the ICs getting now? Can you measure their temperatures?

The current consumption figures you've given are reasonable for both ICs. The 555 is supposed to draw some current. At 8 mA and 12V it will be dissipating about 0.1W which could cause a temperature rise of as much as 10 degrees Celsius above ambient. That would be normal and acceptable. The 40106 should not be warmer than ambient temperature.

As you mentioned, I am working in a company which manufactures these boards and I am testing the functionality of these boards.I just observed the heating of these IC's while testing and I am just trying to figure out the reason for this.

The temperature of IC 40106 is 40 degrees Celsius and IC 555 is 34 degrees Celsius.

thanks,
paddy
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
Joined
Nov 28, 2011
Messages
8,393
OK. If only one gate (pins 3 and 4) of the 40106 is used, exactly as shown in your schematic, and the inputs of the others are all grounded and the outputs are not connected, and the power supply is a clean 12V, I can't see any reason why the 40106 would be getting warm.
 
Top