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Marq
Joined: 06 Oct 2009 Posts: 9
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Is PIC spoiled easily? |
Posted: Fri Oct 09, 2009 8:25 pm |
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I have encountered some problems, when I am using a new PIC16F877 and try to program the coding onto it. At the first few times of trying it works just fine, but then the error come in like exp: rom error at 0x01. I am suspecting whether the PIC is spoiled already or the programmer itself got problem? And I experience heating on my PIC16F once before that where the PIC get warmer than normal. Can the PIC just be spoiled for one heating issue, and cannot be used anymore?
The programmer I am using is QL2006 from China manufacturer.
Can some help to enlighten my problem? |
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Ttelmah Guest
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Posted: Sat Oct 10, 2009 3:12 am |
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For what it is (a processor), the PIC is quite rugged. Often taking abuse yet surviving. _But_ it is not a 'power' device, and as such, the internal gates are _small_.
Now, a PIC, can generate some heat, yet be working 'in spec', and never give problems. You don't say which PIC is involved. There is a significant difference in the maximum power dissipation from some of the smaller devices, versus the larger ones. However the maximum dissipation of a typical 40pin PIC, is less than 1W. How much the package will heat from this, will depend on how the chip is mounted (soldered to a PCB, plugged into a socket, etc..). For instance, you can legitimately drive 10mA from each output pin on a 8bit port, and be completely 'in spec', with the device drawing perhaps 100mA, and the device probably dissipating over 1/4W. However do the same, with all the pins on a 40pin device, and the total current being drawn, and dissipation will be outside the spec.
You can destroy a PIC quite easily, by driving an overvoltage into a pin, while it s fed from a supply with significant load on it. Each pin is rated at 20mA for 'clamping', and driven like this, the chip will get warm, and die quite quickly. Here, the total dissipation may well be less than on the 'OK' example above, but because the power is all being driven through just one output gate, this can be easily destroyed.
Typically a chip in normnal use, may well feel fractionally warm, but if it ever gets really hot, something is wrong.
It is not clear from your posting whether the chip was getting hot when being programmed?.
Yes a chip can easily be destroyed in a few uSec, if significant current is driven into a pin where it shouldn't go.
Best Wishes |
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Marq
Joined: 06 Oct 2009 Posts: 9
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Posted: Sat Oct 10, 2009 9:05 pm |
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Thanks for the reply, i think my PIC burn out due to over voltage (it really get hot), it shouldn't be the problem with the programmer.
Because i am drawing voltage from the ac to dc adaptor at (9V setting) and through the voltage regulator and input it into my PIC. I am suspecting the problem are due to 9V setting too high and the capacitor value used for the LM7805 is 32 micro Farad (at the input pin). Anyone got any suggestion or changes that i should make to decrease the vulnerability of the PIC to overvoltage? |
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