[sdiy] converting a 10v p to p to a 0-5 volt signal

[Neil Johnson]

Hi,

Adam Schabtach wrote:
> Clipping at 5.1V isn't really good enough, though. The Absolute  
> Maximum
> Ratings for the ATmega microcontrollers I use specify an upper  
> limit of
> Vcc+0.5V on any pin.

I don't think you understand the problem you are trying to solve.   
Its not the voltage that is the problem - its the current that flows  
into/out of the pin when the applied voltage is large enough to turn  
on the internal ESD protection diodes.

A common and cheap input protection is a current limiting resistor  
(say 220ohms) followed by a diode to each rail (VDD, GND) just before  
the pin.  Beyond that you can go for resettable polysilicon fuses and  
schottky diode bridges if you want bullet-proof inputs (not  
mentioning filter capacitors, etc, for EMC .. but that's another tale).

Neil
--
http://www.njohnson.co.uk