Exploding driver chip
Tom540, Tue Dec 19 2006, 07:56AMToday when I was testing a board I had made and as I probed the power pins of a ucc37321 the chip exploded much like a mosfet does. I think I shorted an output pin to the +15 volt pin. I wonder if the 11,000uF worth of caps I have on the +15VDC line has anything to do with it. Still seems odd that the chip would try and put out enough power to send chunks of plastic into my face.
Re: Exploding driver chip
ragnar, Tue Dec 19 2006, 08:28AM
What usually happens to me with dying UCCs (I seem to be infamous for pushing them to stupid frequencies, stupid voltages and stupid powers) is smelly brown crap starts bubbling out a little pinhole or crack that forms above the output stage.
Because the outputs are so low impedance, it's easy to latch the chip by shorting one or other output to a rail. If he latches, he's as good as gone... Sometimes if you're quick, though, you can kill the power before they get too hot, and once they cool down again they're good to go.
I sand my multimeter probes down until they're sharp points to alleviate this issue, or solder sewing pins to them. =P
ragnar, Tue Dec 19 2006, 08:28AM
What usually happens to me with dying UCCs (I seem to be infamous for pushing them to stupid frequencies, stupid voltages and stupid powers) is smelly brown crap starts bubbling out a little pinhole or crack that forms above the output stage.
Because the outputs are so low impedance, it's easy to latch the chip by shorting one or other output to a rail. If he latches, he's as good as gone... Sometimes if you're quick, though, you can kill the power before they get too hot, and once they cool down again they're good to go.
I sand my multimeter probes down until they're sharp points to alleviate this issue, or solder sewing pins to them. =P
Re: Exploding driver chip
Bjørn, Tue Dec 19 2006, 08:42AM
That happens from time to time. Some MOSFET driver chips seems to fail in that way fairly often. I did the same once with a 7805 regulator that is supposed to be short circuit proof.
When you short pins there can be significant currents, sometimes these currents take paths through the silicon that is not intended and they can cause transistors to latch up and the chip can malfunction in any number of bad ways.
Bjørn, Tue Dec 19 2006, 08:42AM
That happens from time to time. Some MOSFET driver chips seems to fail in that way fairly often. I did the same once with a 7805 regulator that is supposed to be short circuit proof.
When you short pins there can be significant currents, sometimes these currents take paths through the silicon that is not intended and they can cause transistors to latch up and the chip can malfunction in any number of bad ways.
Re: Exploding driver chip
..., Tue Dec 19 2006, 03:22PM
But the absolute best way to kill a ucc is to be using it in a topology with no GDT's, (ucc connected directly to the fets) and then get a fet that decides to short out on you. I once had a ucc blow up so violently I thought that an electrolytic cap had exploded! The top 1/2 of the chip completly blew off, and I don't think that the die is doing too well.
..., Tue Dec 19 2006, 03:22PM
But the absolute best way to kill a ucc is to be using it in a topology with no GDT's, (ucc connected directly to the fets) and then get a fet that decides to short out on you. I once had a ucc blow up so violently I thought that an electrolytic cap had exploded! The top 1/2 of the chip completly blew off, and I don't think that the die is doing too well.
Re: Exploding driver chip
Avalanche, Tue Dec 19 2006, 04:49PM
I've never blown up a driver chip that badly
In fact so far I've only destroyed one pair of UCCs from the bulk buy, and they just failed with no spectacular result
I noticed the UCCs seem to have what looks like a little hole in them, this really fooled me at first when I was having some problems with a coil; "what? UCCs blown again? And I don't think I even ran the coil this time!"
Avalanche, Tue Dec 19 2006, 04:49PM
I've never blown up a driver chip that badly
In fact so far I've only destroyed one pair of UCCs from the bulk buy, and they just failed with no spectacular result
I noticed the UCCs seem to have what looks like a little hole in them, this really fooled me at first when I was having some problems with a coil; "what? UCCs blown again? And I don't think I even ran the coil this time!"
Re: Exploding driver chip
Andrea87, Tue Dec 19 2006, 05:59PM
place a fast 325 or 400mA fuse on the supply of each gate driver, it will save your gate drivers.
allways remember to decouple the output of the drivers with a 0.3 to 1µF cap, depending on the frequency. I've just blown some drivers with my induction heater, next time I'll be much more careful about it!
Andrea87, Tue Dec 19 2006, 05:59PM
place a fast 325 or 400mA fuse on the supply of each gate driver, it will save your gate drivers.
allways remember to decouple the output of the drivers with a 0.3 to 1µF cap, depending on the frequency. I've just blown some drivers with my induction heater, next time I'll be much more careful about it!
Re: Exploding driver chip
Tom540, Wed Dec 20 2006, 04:42AM
The chip didnt even have a gate drive transformer attached to it. I guess it must have latched low when my meter probe slipped and shorted the output to the +15V pin. I wonder if it could be pushed hard enough to do that driving a gate drive transformer? Honestly it's kinda of cool when the go violently instead of just heating up and fizzlling out.
Tom540, Wed Dec 20 2006, 04:42AM
The chip didnt even have a gate drive transformer attached to it. I guess it must have latched low when my meter probe slipped and shorted the output to the +15V pin. I wonder if it could be pushed hard enough to do that driving a gate drive transformer? Honestly it's kinda of cool when the go violently instead of just heating up and fizzlling out.
Re: Exploding driver chip
..., Wed Dec 20 2006, 05:02AM
If you do not put external diodes on the output they can 'latch up' and short out , and if you have enough filter caps on the board that can be decently spectacular ;)
..., Wed Dec 20 2006, 05:02AM
If you do not put external diodes on the output they can 'latch up' and short out , and if you have enough filter caps on the board that can be decently spectacular ;)
Re: Exploding driver chip
Colin 99, Thu Dec 21 2006, 03:10AM
Avalache,
The little hole is for the magic smoke to escape
I was building one of Dan McCulleys Plasmasonic boards and I had an inverting driver that was non-inverting. It took out two of my driver chips and I had to order more samples.
Shaun
Colin 99, Thu Dec 21 2006, 03:10AM
Avalache,
The little hole is for the magic smoke to escape
I was building one of Dan McCulleys Plasmasonic boards and I had an inverting driver that was non-inverting. It took out two of my driver chips and I had to order more samples.
Shaun
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