K10 Series ADC Internal Reference PPM?

[tomekkicaj]

Hello All,

I'm studying K10 Docs and I found no information as to the temp. stability of the internal 1,2V reference.

Does anyone know the PPM of the voltagere reference?

How good is the  ADC in K10 ? So far I've been using Sigma Delta MCP3425 and it worked very well.

Generally  ADCs built it microcontrollers (especially AVR)  are crap so i wonder how it looks with K10?

Thanks and regards

Tomasz

[tomekkicaj]

Thank you guys,

MCP3425 has int. ref of 2.048V ± 0.05%  , Integral Nonlinearity 10ppm FSR, Gain Error Drift of 15 ppm/°C.

The accuracy of the ref voltage is not that important to me as I calibrate the end system anyway.

My concern is the -20 to +80 temperature stability of the internal rev voltage which is not stated in the datasheet.

I wonder if I should stay with the proven MCP3425 or go for the internal ADC.
I'm measuring with 12bits 0-200mV signals at 5 samples/sec.

Regards

Tomasz

[egoodii]

It's not clear how the MCP3425 defines 0.05% and 15ppm/C -- looks to me like over temp the total conversion error runs from +0.15% to -0.3% (figure 2-6), which is much worse than the MAX6070B.

[Paul_Tian]

Hi, Tomek

After factory trimmed, the range of VREF is 1.1584V to 1.2376V.

Hope my reply can help you.

Best Regards

Paul

[egoodii]

To use your vernacular, 'crap', at +/-3.3%

I feed VrefH with a $1 REF3030AIDBZ, at 0.2% 65ppm/C.  The MAX6070B is nice too...

[Paul_Tian]

Hi, Earl

After trimmed, you can get 0.5mV accuracy. You can find VREF_TRIM register in our reference manual.

Hope my reply can help you.

Best Regards

Paul

[egoodii]

OK, but then 80mV drift across the temperature span.  Isn't that on the order of 500ppm/C?  And what about long-term-drift?