HSADC accuracy

[lpcware]

Content originally posted in LPCWare by baum on Tue Jul 07 00:24:22 MST 2015
Hi,

I'm a student working on a project with the LPC4370. My current goal is to make the HSADC work precise, for measuring with a accuracy of 1mV. As it seems that I can't reach this goal, I was wondering if someone else has cracked this mark. If yes, I'd like to now following points:

- was it hard to get there?
- at witch samplerate does the HSADC work?
- are there more channels used or only one?
- do you use one ground plane for analog and digital signals, or are they separated?

looking forward for answers

greetings
baum

[lpcware]

Content originally posted in LPCWare by baum on Wed Jul 08 00:19:34 MST 2015
thanks for your reply rocketdawg.
I've been already thinking about your points. but I was hoping that the sampling depth won't be large as the application is time critical(it will be a digital PID controller).
Another point is, that the good measure equipment is broken and send in for service. I hope that the service guys won't spend to much time on it, so that I can spent deeper investigations in noise reduction.
for noise reduction, witch type of ground plane would you recommend for the LPC4370? One with splited digital and analog Ground or one with only one ground for digital and analog signals?
Maybe someone else has experience at that point. Until now I'm working with a splited one.

greetings
baum

[lpcware]

Content originally posted in LPCWare by rocketdawg on Tue Jul 07 15:21:57 MST 2015
a 12 bit ADC should be capable of better than 1mv, but the ADC does have "effective number of bits" at 10.4 @ 1Mhz sampling
BUT, you will have to have a very very stable:
Voltage Reference
Power Supply,
Effective decoupling to reduce noise,
and large sampling depth to average out noise.