IRS21844S from difference suppliers - slight differences

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hello to all the members.
I have a question.
I'm repairing an EMPHASER EA15000SPL (output mosfet and short ICs).
I replaced all the IRS21844S, but unfortunately I had 3 IRS21844S coming from Mouser and 1 IRS21844S coming from TME, all 4 chips are original and perfect, in fact I ran all the tests, and the signals are all ok, but I noticed that the 3 Mouser's IRS have a slightly lower output than TME's IRS (they all work perfectly even when installing mosfets).
I noticed this small difference only by looking at the waveform on the oscilloscope on the low side gates before install the fets.
I will make a small example by drawing by hand.
Have any of you ever used IRS chips of different suppliers?
I can assure you that all IRSs are original, even if they come from different suppliers.
 

Attachments

  • 20191116_094241.jpg
    20191116_094241.jpg
    223.1 KB · Views: 74
Ive always matched mine with the same date code in the amplifiers just to be safe. Then again Ive had atleast one fet from each driver blow usually.

If I were you I would find an identical amp and test that driver board in that amp to see if the results are the same.

Maybe something to do with the date code, shelf time, or humidity of the IRS21844S?

I am curious as well now.
 
Would you be concerned about the Mouser ICs if you would not have seen the waveforms from the other IC?

Do all of the ICs have the exact same supply voltage (measured directly across VCC and COM very near the IC (don't slip if measuring on the IC pins).
Actually I also installed the mosfets (only 2 per branch for each amplifier) using some test IRFP360LCs.
The amplifier worked well, the switching frequency was good (130khz, variable depending on the battery voltage) identical for all 4 amplifiers.
Then I removed the test mosfets to proceed with the installation of 16 new FDA24N40Fs, but first, I wanted to do a double test, so I got to where I am now.
Anyway, I installed the new mosfets, and the amp works flawlessly, so I assume there are no problems with that small difference in amplitude.
To answer your question, if I hadn't noticed this, I probably would have installed the mosfets directly, but it was good to see it, you know better than anyone else that these amplifiers are real nightmares even for a little nonsense.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.