M102v5-10: Calibrating a 10-bit equipment with 3.5 digit multimeter?

[technix]

My dummy load is finally working! M102v5-10 is a test load with 10 bit resolution but it requires a few calibration values (Vref from MC1403 voltage reference chip, Vdac_min and Vdac_max from TLC5615 10-bit DAC, as well as Rsense from the power sense resistor) stored in its on-board EEPROM to work. The best multimeter I have is a 3.5 digit Zhenxing DT-890.

Can I calibrate my M102v5 with this 3.5 digit multimeter, or should I go for a 4.5 digit multimeter or better? 10 bits is a range of 0 to 1023, covers slightly more ground than the 3.5 digit meter.

By the way, the internal calibration registers are 16 bits long.

[singapol]

My dummy load is finally working! M102v5-10 is a test load with 10 bit resolution but it requires a few calibration values (Vref from MC1403 voltage reference chip, Vdac_min and Vdac_max from TLC5615 10-bit DAC, as well as Rsense from the power sense resistor) stored in its on-board EEPROM to work. The best multimeter I have is a 3.5 digit Zhenxing DT-890.

Can I calibrate my M102v5 with this 3.5 digit multimeter, or should I go for a 4.5 digit multimeter or better? 10 bits is a range of 0 to 1023, covers slightly more ground than the 3.5 digit meter.

By the way, the internal calibration registers are 16 bits long.

It all depends on how accurate or stable your various cpmponents used in your circuit. Why not use a 3.5 digit meter averaging +/- 1% tolerance when MC1403 voltage reference accuracy is also 1%? Make sense...that's provided you have confidence in 3.5 digit meter calibration. See the multimeter article.
In practice one would use a higher accuracy meter to calibrate but since you don't have one or want to spend money 3.5 digit meter will have to do.

Look at the big picture now...you are using 10 bit dac, now to get true 10 bit accuracy or resolution is 1%
MC1403 suitable?. Temperature , non linearities in dac and quality of Vref influence results. So will you get 10 bit resolution with MC1403?. The temperature coefficient of MC1403 is typically 10 ppm to maximum 40ppm at 25 degree celcius. According to Walt Jung article: Getting the most of voltage reference, to get true 12 bit accuracy one would need a 5 ppm voltage reference so MC1403 is good for at best 9 bit to 8 bit resolution. See page 16.

So is 8 bit good enough for your application? Why not since it's a fun project. Even digital scopes use 8 bit adc. It really depends on what you want or designing for. Congratulation on your success.

MC1403 datasheet:
http://www.st.com/web/en/resource/technical/document/datasheet/CD00000870.pdf

Getting the most of voltage reference - Wat Jung:
http://waltjung.org/PDFs/Getting_the_Most_from_IC_Voltage_References.pdf

How to determine multimeter accuracy:
http://www.designworldonline.com/how-to-determine-digital-multimeter-accuracy/