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PSoC 5, 3 & 1 MCU

Anonymous
Not applicable

I am trying to read a voltage(AC) value from a shunt resistor and I am supposed to do measurement very precise with high number of  decimals. I am using a 4m(ohm) shunt resistor and the voltage will be very low like microvolts level. First , I need to amplify it with PGA or OP-AMP then the signal move to the ADC. This is where I confuse ! How do I make 10.000+ measurements with ADC or any kind of component than PSoC5 contains. Thank you for your attention... 

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1 Solution
Bob_Marlowe
Expert II

Welcome in the forum!

   

The PSoC5's SAR has got 12 bit resolution and can easily handle >500 ksps.

   

The DelSig ADC reaches with 17 bit resolution up to 12000 sps (@16 bit >40ksps)

   

so this wil satisfy your needs and gives some room for filtering (averaging) noise.

   

What are you going to do with the results? When thinking of transmitting via an interface think of the needed bandwidth.

   

 

   

Bob

View solution in original post

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6 Replies
ETRO_SSN583
Esteemed Contributor

10,000 measurements at what resolution ? 20 bits, 18, 16, .....the DelSig has limitations of sampling

   

rate vs resolution. Are you seeking absolute accuracy or relative accuracy ? The SAR is capable of 1Msps

   

at 12 bits.

   

 

   

You will need to do CDS -

   

 

   

http://www.cypress.com/?rID=49159     AN66444 - PSoC® 3 and PSoC 5LP Correlated Double Sampling to Reduce Offset, Drift, and Low Frequency Noise

   

 

   

Consider also using the DFB for filtering.

   

 

   

Lastly at 4 mOhm you have some serious connection issues in terms of thermoelectric

   

generating connections -

   

 

   

https://www.dropbox.com/s/aq8pyz7d9oc8r5t/analog_digital_conversion.zip?dl=0

   

 

   

Regards, Dana.

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Anonymous
Not applicable

Thank you so much , I thought 12 bit or 16 bit resolution and I will check and try to apply them

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Bob_Marlowe
Expert II

Welcome in the forum!

   

The PSoC5's SAR has got 12 bit resolution and can easily handle >500 ksps.

   

The DelSig ADC reaches with 17 bit resolution up to 12000 sps (@16 bit >40ksps)

   

so this wil satisfy your needs and gives some room for filtering (averaging) noise.

   

What are you going to do with the results? When thinking of transmitting via an interface think of the needed bandwidth.

   

 

   

Bob

View solution in original post

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Anonymous
Not applicable

Thanks Bob , I thought 12 bit or 16 bit resolution. What I need to do is , I need to read the voltage value from shunt resistor and amplify it , convert it and make power consumption calculation.

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ETRO_SSN583
Esteemed Contributor

Additionally this handbook has many recommendations for low level noisy measurements.

   

 

   

http://info.tek.com/KI-Low-Level-Measurements-Handbook-LP.html

   

 

   

Are you measuring AC power line current ?

   

 

   

Regards, Dana.

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Anonymous
Not applicable

Thank you again Dana , Yes I am measuring AC power line current

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