ATtiny15 fried.. Something wrong with my schematic ?

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extin
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Posted by extin: Fri. Jul 22, 2005 - 03:30 PM
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The board couldn't be more simple, but is it too simple ?
It's an sender for IR beam barrier. It would have cost the same to do it the analog way so I desided to use a ATtiny15 for it :)
The design worked fine for a few days but suddenly stopped. I checked what's wrong and found the tiny burning hot :(
Any advice ? Is it the design or did I just have an monday piece :)

The tiny is powered by an 4.5V battery.

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AVR Microcontrollers, megaAVR and tinyAVR
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KKP
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Posted by KKP: Fri. Jul 22, 2005 - 03:36 PM
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No decoupling whatsoever?

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glitch
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Posted by glitch: Fri. Jul 22, 2005 - 03:53 PM
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Schematically your LED is backwards, so if it did work, I assume you corrected this.

The bypass cap, while a good idea, is not likely going to be the cause of your problem. I suspect you have a short, or mis-connection, somewhere in your prototype.

Also be sure to enable the BOD on the AVR, strange things can start to happen when VCC drops too low. with that LED consuming ~20mA, your battery won't last too long.

Writing code is like having sex.... make one little mistake, and you're supporting it for life.

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extin
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Posted by extin: Fri. Jul 22, 2005 - 04:57 PM
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glitch wrote:
Schematically your LED is backwards, so if it did work, I assume you corrected this.

:oops: So it seems, the schema was drawn after making the proto. Proto works, well, worked :)

glitch wrote:
The bypass cap, while a good idea, is not likely going to be the cause of your problem. I suspect you have a short, or mis-connection, somewhere in your prototype.

Triple checked the board, it's only 5x8 holes in veroboard so nothing strange there. Think I'll add the cap just to be sure..

glitch wrote:
Also be sure to enable the BOD on the AVR, strange things can start to happen when VCC drops too low. with that LED consuming ~20mA, your battery won't last too long.

I will use 4.8V NiMH accu in the future.

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