Lpc2000

Hello Rob,

I will be interfacing to various hall effect sensors.
Absolute accuracy doesn't really have much to do with my selecting a 
24bit A/D though.  I will only need a voltage measurement accuracy on 
the order of 0.1%.  In the past I have used various high resolution 
sigma-delta converters and have never achieved 24bit noise free 
resolution, but I have had designs which have routinely achieved say 
19-20 bit resolution at low data rates.

My real reason for using a sigma-delta A/D is the inherent linearity, 
and wide dynamic range.  In other words I may at times have to 
measure a change of 0.1Gauss in the presence of a 10kGauss field even 
though I can't hope to have an absolute accuracy of 0.1G out of 10kG 
(0.001%) with a hall effect sensor.

Jeff

--- In lpc2000@yahoogroups.com, Robert Adsett <subscriptions@a...> 
wrote:
> At 05:24 PM 1/28/05 +0000, you wrote:
> >I have not used any of the LPCxxx devices before.  I am considering
> >using an LPC2138 in an application which must read data from an
> >ADS1271 24bit A/D using an SPI interface.
> 
> 
> Actually, I have another question.  As a matter of curiosity what 
kind of 
> source do you have that's 24 bit's accurate?  And what are you 
using for a 
> reference?  (24 bits implies something like 1 part in 10,000,000.  
or 0.2 
> microvolts in 5V)
> 
> Robert
> 
> " 'Freedom' has no meaning of itself.  There are always 
restrictions,
> be they legal, genetic, or physical.  If you don't believe me, try 
to
> chew a radio signal. "
> 
>                          Kelvin Throop, III