AVR-Chat

On Feb 13, 2005, at 5:13 AM, Valerij Avrealij wrote:

> When I in system program my tiny15 the current more than 200mA!!!
> The chip and 7805 are hot. I use Altera ByteBlaster programmer with 
> special PC software.
> Very interesting: when I connect swiched ON ISP the current is normal,
> when I OFF it and then ON the current more than 200mA
> How this problem can be solved?
> P.S. Using this ISP cable I successfull program mega8 chip.

The problem is that your 7805 isn't protected against "back feeding." 
Its trying to regulate its output which is being driven higher than its 
unpowered input by your ISP cable.

You need a different model of regulator, else insert a diode between 
the existing regulator and the ISP connector.

Or you could power your circuit by normal means when using the ISP. 
This will keep your 7805 happy.

--
David Kelly N4HHE, dkelly@HiWAAY.net
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Whom computers would destroy, they must first drive mad.