Trishool
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On 2001-10-27 22:40, MITSUKO wrote:
You could also use LTC1286 .
12 Bit serial AD with integrated s&h circuit .
Mitsuko
On 2001-10-29 11:22, Alexg wrote:
Hi,
Be very carefull with the board layout when doing 12 bit conversions. It is pretty hard to get more than efectivy 10 bits if you do not make a good ground plane, isolate as much as possible the digital and analog side of the circuit and have very solid power connections right under the AD converter. There are some nice application notes on the subject that are well worth reading. Do a google search and you will fing many. Microchip has a nice and simple one.
Best regards,
Alexg
On 2001-10-29 20:38, Trishool wrote:
when ever I read my temperature sensor I could read a difference of 2 degree C .What would you suggest is this a problem with the reference voltage applied ???.i have made the demo board for the time being but will consider your suggestions isolations I have already done should the reference to ADC and its VCC be seperated from the microcontroller also??
On 2001-10-29 23:59, Alexg wrote:
Usually the greatest noise generator are clock circuits and the microcontroller itself. If you have a single microcontroller and the AD converter use 2 different 78L05 regulator for each one !! They are cheap and in that way you will pretty much isolate the VCC noise. Use a HUGE ground plane for your analog circuit and another one for the digital part of the circuit. Do not make just one big ground plane. Connect the analog and digital grounds right under the AD or at the power supply. I prefer under the AD, but many different opnions there. Is your sensor stable enough to give you better than 2 C measurements ?? How fast do you need to measure ? If you do some readings and take use a moving average filter you might get better results because random noise tends to be cancelled. Many things to look at !! Check on the ones above and tell us how it goes. Do a search at microchip, they have a nice app note on 12 bits AD board layout.
Best regards,
Alexg
Hi
It would be good if the link is given here I searched but couldnt find any.
Regds
Ts
On 2001-10-30 17:14, johnyaya wrote:
Alexg - Not entirely true about single ground planes. Printed Circuit Design magazine ran an article about using ground planes with analog and digital circuits. Good reference article.
On 2001-10-31 15:56, Trishool wrote:
Alexg
Thanks The Article is really a worth reading and very Interesting.
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