Re: 24 Bit, dual channelADC, SPI Slave, 85 DegC (or more)
- From: "Bill Davy" <Bill@xxxxxxxxxxxxxxx>
- Date: Wed, 30 Sep 2009 11:32:12 +0100
"Mark Borgerson" <mborgerson@xxxxxxxxxxx> wrote in message
news:MPG.252bb61bb210a8fa98990f@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
In article <7iedi5F2vcad9U1@xxxxxxxxxxxxxxxxxx>, Bill@xxxxxxxxxxxxxxx
says...
Can anyone point me at something? Not going fast (480 samples/sec). Must
be
available immediately (going down an oil well just after Christmas).
TIA,
Bill
There are a number of things you need to watch out for, in addition to
the temperature specification:
Very few ADCs will give you 24 bits of noise free data at 480 samples/s.
multi-channel Delta-sigma ADCs often incur a significant timing penalty
when switching between channels. To collect two channels at
480samples/s you may actually have to use a sampling rate 3 to 5 times
higher to allow the internal digital filters to settle after switching
the multiplexer.
Your best bet might be to use two separate ADCs such as the CS5532.
That would allow you to avoid the timing penalty incurred when switching
channels.
Mark Borgerson
Hmmm, they seem to draw 500 mW (max) each! Also temperature range limited
to -40°C to +85°C. Still, I will point this device out.
Still, very interesting.
I've looked at how much time jitter is allowed to avoid disturbing LSB with
maximum swing. It's not very much! Perhaps the application really calls
for 17 bits. Still, I am only a programmer :-)
Bill
.
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- From: Bill Davy
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