cheap 24 bit ADC

David B

I've been working with a project in which my propeller runs a 24 bit ADC, the ADS1210, fed through an 8 channel CMOS analog switch to provide 8 analog inputs, and have been very happy with it overall.

The problem I'm having is to get low noise per measurement, the conversion has to run very slowly. Also, as a sigma-delta converter, whenever the external switch channel is changed, the chip has to run a few dummy cycles to flush its buffers before it'll deliver a valid new measurement, slowing down the conversions even more.

So while the converter and switch work great, I'd like to be able to make multiple measurements faster. So I started looking into running multiple chips in parallel.

This chip is $24 at Digikey, and most other 24 bit ADCs are in that same price range, and my home hobbiest budget isn't about to buy a bunch more at that price.

But while I was browsing Digikey, I saw a listing for an ADC converter, the Nuvoton NAU7802, almost the same specifications - 24 bits, sigma-delta, etc., for two bucks! $2.20!

Has anyone heard of this chip? How can it sell for so cheap?

I ordered a few to play around with, to pass the time over the holidays.

kwinn

I have not used either chip, but from what I see in the data sheets the specs are not that far apart. Looks to me like using multiple NUA7802's will take care of most of your problems. No switching channels, no buffers to flush, and all channels read in parallel.