ADC10 Vs SD16?

[jsolarski 94]

What would the advantage or disadvantage to using the sigma-delta ADC versus the normal ADC on the msp430 chips?

 

I have read and researched the sigma delta and the regular adc and couldn't find a reason to use one over the other.

Just a general question, i do not have a project or application in mind.

[juani_c 66]

I personally prefer the ADC10, Its has more stable readings than the SD16.

[gatesphere 45]

If you're looking for precision, the SD16 wins out simply because it's 16 bits versus 10. However, I've only ever worked with the ADC10.

[NJC 17]

I know my response comes a bit late, but I have worked with both quite extensively in multiple applications.

 

The biggest difference is what gatesphere mentioned, the vertical resolution (how many bit's the ADC is) is much larger with the SD16. There are many applications where 10 bits is not enough (for example, an EEG). The other major differentiating factor is speed, the ADC10 is significantly faster than the SD16; if I remember correctly the SD16 in the F2013 has a maximum sample speed of about 4kHz. Remember that the Sigma Delta ADCs oversample the signal by multiple orders of magnitude and then does something called "digital decimation" to get the 16 bit output. This is a bit complicated to understand, but all the end user needs to know is that the Nyquist frequency is very different for SD16s than it is for the ADC10.

 

Basic moral of the story, if you need speed choose the ADC10, if you need vertical precision use the SD16.

 

Hope that helps.

[jsolarski 94]

@NJC A late answer is better then no answer.

That helped a little, and the the conclusion that i came to is sd_16 is complicated but very precise and slow. The ADC10 is fast and easy setup but with less precision. My suggestion is to use the ADC10 when possible and use the SD_16 only when you need the accuracy and precision of 16 bits with oversampling.

 

Maybe after i get finished with my current projects i will do a side by side comparison of them.

[bluehash 1,581]

sd_16 is complicated but very precise and slow

I know setup is complicated, but the TI's released GRACE, that might help you setup.

[jsolarski 94]

im looking forward to trying grace out as long ans my CCS for linux works like it should

with this new OS (pclinux) i have no idea what i may have to setup

[NJC 17]

Yeah, the setup is definitely the hardest part. I'm excited to see how well GRACE works, I only found out about it from here yesterday.

 

Also, I forgot to mention one thing. Another HUGE difference between the two ADCs is that the SD16s reference voltage is a true reference voltage which allows for differential inputs. That is a huge benefit if you have a sensor which provides a differential output. What this means is that if your sensor outputs a negative voltage, the SD16 would make your life easier.

[bluehash 1,581]

That is a huge benefit if you have a sensor which provides a differential output. What this means is that if your sensor outputs a negative voltage, the SD16 would make your life easier.

Very handy in brushless motor control, where phase currents go negative. I'm not sure the MSP430 has the horsepower to do it.

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