ADC with DIP?

Rayman

Anybody gotten Sigma-Delta ADC to work with the DIP version of the Prop?· (With through-hole components)

I'm pretty sure it won't work on a breadboard, but maybe on a custom PCB it could work?

Maybe dropping the operating frequency would help...

Mike Green

Dropping the frequency will help. Putting the feedback resistor and capacitors at the DIP pins, perhaps using surface mount parts for those will help. Even with the surface mount Propeller, the feedback resistor and capacitors have to be mounted as close as possible to the chip leads. There was someone who did get Sigma-Delta ADC working with through-hole components by dropping the clock frequency. Remember that you can get Sigma-Delta ADC to work even with a Stamp if you slow it down enough.

Leon

I've had it working with the DIL chip on a home-made PCB with a prototyping area using through-hole parts. The leads were as short as possible. I used the standard 80 MHz clock. I didn't check the performance in detail, I'd use a proper ADC for a serious application.

Leon

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Post Edited (Leon) : 10/8/2008 5:21:59 PM GMT

Ken Peterson

I have used Delta-Sigma ADC several times with many different configurations (including the DIP) and have not had as many problems as others seem to.· I see others have also gotten it to work without the caps - just using stray capacitance.· However, if you're going to be sloppy with your wiring don't expect a lot of precision or noise immunity. You get pretty much what you pay for. If you need 12-bit precision you're probably better off using a dedicated IC.

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Post Edited (Ken Peterson) : 10/9/2008 12:31:03 PM GMT

Rayman

Thanks Ken. It's good to hear that it can work...

I don't know if Parallax has shown photos of the wire bonding inside the DIP chip, but I'm assuming that adjacent pins run quasi-parallel into the chip. So, I'm going to use 5 pins nearest the center of the DIP and set 3 of them to ground to make transmission-lines with the 2 real pins being used...

Sapieha

Hi Rayman.

It is one thread that describe bonding inside for ADC posiblites

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Nothing is impossible, there are only different degrees of difficulty.
For every stupid question there is at least one intelligent answer.
Don't guess - ask instead.
If you don't ask you won't know.
If your gonna construct something, make it·as simple as·possible yet as versatile as posible.


Sapieha