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Registered Member #580
Joined: Mon Mar 12 2007, 03:17PM
Location: Melbourne, Australia
Posts: 410
Does anyone else experience a higher failure rate of the UCC27321 and UCC37321 (non inverting) compared the the UCC27322 and UCC37322 (inverting) type?
Registered Member #580
Joined: Mon Mar 12 2007, 03:17PM
Location: Melbourne, Australia
Posts: 410
by x, i man 2 or 3. I have edited my post. it seems to be uneven failure rates even if it is the same load between the 2 types. Recently, i had one fail with no load at all. Brand new.
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
You might try digging through the archives, I remember that Matt B (member blackplasma) was pushing the ucc3232x chips to excessively high frequencies and decided that one of the chips was notably faster than the other.
If the resistor between the ucc and the gate is on the same order as the output impedance of the ucc chip it could be that the chip with a lower output impedance is working harder, and heating more. Or in the converse case if the gate resistor is large the chip with the higher output impedance will be dissipating more power due to ir losses and heating more.
Registered Member #1617
Joined: Fri Aug 01 2008, 07:31AM
Location: Adelaide, South Australia
Posts: 139
Hi, Do you use clamping diodes on the output of the chip? I've killed quite a few, then as soon as I put clamping diodes on the output, Ive never killed one (Although I now usually use the TC44xx ones)
Registered Member #235
Joined: Wed Feb 22 2006, 04:59PM
Location:
Posts: 80
I re-read the OP. The UCC37321 are the INVERTING type. UCC37322 are NON-inverting.
I have run with clamping diodes and without; I haven't noticed a failure trend.
However, I did have a bridge,2 pair in Push-Pull, of them fail similar to Avi. The UCC's had no logic input, just bus voltage and they quickly sizzled and popped. I am still boggled by this failure.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
maybe the non-inverting chip can "catch" positive feedback (e.g. with high impedance on the input), start oscillating at a very high frequency and kill itself?
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non inverting UCCx7321
