Ways to test a switching IC like TOP266EG with a multimeter?

In summary, there is no recommended way to test a switching IC TOP266EG with a multimeter outside of its card circuit, even after uninstalling the component. The datasheet for the IC provides test circuits, but these require a more sophisticated setup. Additionally, the most common cause of failure for these ICs is a destroyed output MOSFET. However, it is not possible to determine if the IC is functioning properly with just an ohmmeter. It is also important to consider any potential misunderstandings about the IC and its circuit before assuming it is broken.
  • #1
cemtu
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TL;DR Summary
What are the ways to test a switching IC like TOP266EG with a multimeter?
What are the ways to test a switching IC TOP266EG with a multimeter?(measuring it outside of card circuit)(after uninstalling the component from the card)

Link to the datasheet: TOP266EG Datasheet(PDF) - Power Integrations, Inc. (alldatasheet.com)

Here is the DATASHEET picture:
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s6v62k4nbd791.jpg

TOP266EG IC HAS THE SAME APPEARENCE
 
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  • #2
What do you mean by "test"? You have a PC board with this circuitry on it and it's not working and you want to troubleshoot it? Or you have the loose IC and want to know some way to tell if it's okay or not?
 
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  • #3
berkeman said:
What do you mean by "test"? You have a PC board with this circuitry on it and it's not working and you want to troubleshoot it? Or you have the loose IC and want to know some way to tell if it's okay or not?
loose IC, yes

"Or you have the loose IC and want to know some way to tell if it's okay or not?"
this, yes.
 
  • #4
cemtu said:
loose IC, yes
Can you say more about *why* you want to do this? Just to practice probing some loose IC? Or is there a reason you are wanting to check out this particular IC?
 
  • #5
cemtu said:
What are the ways to test a switching IC TOP266EG with a multimeter?...after uninstalling the component from the card...
There is no way to 'test' it.
The problem is, that even when it's still installed the only real way to 'test' it is while it's on line voltage.
And that's not recommended if you are not somebody qualified.

ps.: if it's some repair attempt, then the most I would do is to check:
- the fuse: there will be a fuse somewhere
- that resistor connecting to 'V' pin.

Only measure when it's disconnected and already no remnant voltage present on the caps.
 
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  • #6
Short answer, no, not really. ICs with multiple functions require more sophisticated setups. That's why the data sheet will have test circuits in it. There's a reason the datasheet is 40 pages. BTW, thanks for that link, you get an A+ from me for question format!

A common way for these things to die is that the output MOSFET is destroyed. You may be able to test that with an ohmmeter if you can set up the IC* to either try to turn it on, and test for a low impedance, AND to try to turn it off and check for a high impedance. You won't be able to say it's OK, but if you are confident you are setting it up correctly for these tests, you could decide that it's broken.

For ICs like this, my experience is that the problems are usually some misunderstanding about the IC and/or the circuit that it is actually connected to. That, or it's obviously broken. If it has never been used, it should be safe to assume it's OK; these aren't that fragile.

* this would be in a special purpose low voltage test circuit that you make.
 

1. How do I test a switching IC like TOP266EG with a multimeter?

To test a switching IC like TOP266EG with a multimeter, you will need to follow these steps:

  • Set your multimeter to the diode testing mode.
  • Place the black probe on the ground pin of the IC and the red probe on the VCC pin.
  • The multimeter should display a voltage drop between 0.5V to 0.7V, indicating that the IC is functioning properly.
  • Next, place the red probe on the VCC pin and the black probe on the OUT pin.
  • The multimeter should display a voltage drop between 0.5V to 0.7V, indicating that the IC is switching correctly.

2. Can I test a switching IC like TOP266EG without removing it from the circuit?

Yes, you can test a switching IC like TOP266EG without removing it from the circuit. However, it is recommended to remove the IC from the circuit to get more accurate readings.

3. How do I know if my TOP266EG IC is damaged?

If your TOP266EG IC is damaged, you may notice the following symptoms:

  • The output voltage is not stable or is significantly lower than expected.
  • The IC is getting very hot.
  • The IC is not switching on and off as expected.
  • The IC is shorted or has an open circuit.

4. Can I use a multimeter to test all the pins of a TOP266EG IC?

Yes, you can use a multimeter to test all the pins of a TOP266EG IC. However, some pins may require specialized equipment or techniques to test, such as the feedback pin.

5. What readings should I expect when testing a TOP266EG IC with a multimeter?

The expected readings when testing a TOP266EG IC with a multimeter will vary depending on the specific test being performed. Generally, you should expect to see voltage drops between 0.5V to 0.7V when testing the diode function, and voltage readings between 0V to the specified output voltage when testing the switching function.

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