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| Regulator dies and takes whole circuit down with him |
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| iMo:
On that picture above I can see 100uF at the 1117 output.. |
| evansg:
I see, got the point now. Maybe this capacitor causes problems as the datasheet refers to 4.7uF ceramic. (as already mentioned here) I'll check to remove this capacitor and use another lower one. Thanks for the all the help guys! Appreciate it. |
| capt bullshot:
--- Quote from: evansg on October 25, 2019, 02:53:03 pm --- I do not think so as this happens always (based on customer reports) when they plug the socket in the DC IN. --- End quote --- This is a valuable hint to the (possible) root issue: Plugging the DC IN while the external power brick / battery is already turned on (how would one turn off a battery anyway?) can create an overvoltage spike on your input 12V rail. This spike can cause the regulator to internally break down and you know the rest of the story. There's an application note by former Linear Technology addressing this issue - https://www.analog.com/media/en/technical-documentation/application-notes/an88f.pdf TLDR: Add an electrolytic capacitor or any other suitable means to dampen the ringing (in parallel to the DC jack) and your issue will be gone. |
| DBecker:
Characterizing the damage as "explodes" suggests that it is a rapid event. Oscillations would lead to slower overheating which chars the package and board. A shorted package might later overheat, but a shattered package with minimal charring suggests an over-voltage event. That regulator should have a bipolar pass transistor. It should only take a few seconds to check that it doesn't show up as the parasitic diode of a MOSFET. |
| NiHaoMike:
If you don't actually need the low dropout, add a series resistor on the input to make a filter and current limiter. Or use a standard linear regulator like the 7805. |
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