General > General Technical Chat
Why did my LT3042 die?
giosif:
Hi,
I bought one of those little boards found on eBay which use an LT3042 to provide low noise voltage supply.
I set the output voltage to 15V by changing Rset to 150 kOhms, fired it up and all looked good.
I then used it for about 1 hour or so, drawing around 50 mA from it.
During this time, I noticed the LT3042 IC was getting rather hot to the touch, but thought this might be normal.
After the 1 hour, though, the IC died and I am trying to understand the reason for that.
Looking at the datasheet for the IC (to the degree I can read & understand it), I don't think I've exceeded any of its operating parameters (except maybe for heat dissipation?).
Anyone has any ideas?
Of course, this being bought from eBay, that IC could be anything *but* an original LT part, so that is one possible explanation, but I'm trying to see if I might have overlooked something else.
Thanks!
2N3055:
What was the input?
giosif:
Sorry, forgot to mention that: input was 20V.
PeteH:
What did your wire harness look like?
Running the part at 20V when the abs max is 22V with default decoupling on the eval PCB is risky.
Does your load ever change in current?
The chip mounted on a fairly large PCB should be able to handle the ~300mW of loss but would get warm depending on the layout of the board.... Could get very hot if not done well.
Jay_Diddy_B:
giosif and the group,
Are you talking about a board like this one?
It has ceramic input capacitors. It doesn't have an electrolytic capacitor that will provide damping. Have a look at this application note. The application note explains why you need damping.
Link: https://www.analog.com/media/en/technical-documentation/application-notes/an88f.pdf
This is probably why the LT3042 failed.
Jay_Diddy_B
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