Re: [avr-gcc-list] AVR ADC

[Erik Christiansen]

On Tue, Apr 17, 2007 at 09:31:13PM +0200, Joerg Wunsch wrote:
> 
> Temperature and long-term stability are probably by an order of
> magnitude better than accuracy of the initial value.  Too bad they
> don't have any typical data to provide.

Yes, one can scour a lot of datasheets in search of more than the
most basic graphs.

The ATtiny15 datasheet is unusually useful in providing a "Bandgap
Voltage vs Vcc" graph, which shows 4 temperature points "on the 3rd
axis". It seems to show that temperature immunity is best above 5v,
where supply immunity is worst.

The badgap reference construction doesn't seem to be common to all
devices though? The ATtiny26's datasheet shows starkly different Vcc
curves.

The vestigial image, in my mind's eye, of an ageing graph, must have
been unrelated after all, because I can't seem to find it.

The graphs you mention, and similar for amplifier gain, would be very
useful for gauging an AVR's usefulness in all but the most basic
applications. (I'm putting in external amplifiers, because it doesn't
seem wise to trust the on-board ones in the absence of data.)

I wonder whether the PWM3 uses either of the above bandgap references???

Regards,
Erik