ADS122C04: Circuit Design for Low Current [nA] & Low Voltage [uV] Precise/Accurate Measurement.

Arjun Singh

Part Number: ADS122C04
Other Parts Discussed in Thread: ADS131B02-Q1, ADS127L11, ADS1219

Hello everyone,

Can you please suggest set of 24 Bit high speed ADCs & DAC for low current & voltage measurement. I want precise & fast ADC for measuring current in nano Amperes (nA) & voltage in micro Volt (uV).

Necessary speed for data transfer for ADC & reading ADC data. It will be 24 Bit output stream of ADC & 16 Bit input stream for the DAC.

VREF of ADC can be from 2.5V to 5V max but 2.5V is preferable.

Schematic is shown above & since ADC is the bottleneck & speed is paramount, therefore please suggest the part numbers which can give me precise and accurate results.

I have gone through ADS122C04, , ADS1219, ADS127L10, ADS131B02-Q1, ADS127L11, these set of ICs already. Please suggest one.

Thanks & Regards
Arjun

over 2 years ago

0 Bob Benjamin over 2 years ago

TI__Guru** 113765 points

Hi Arjun,

Can you give a little more detail as to the requirements? You say you need 'speed', but just what does that mean? With higher speed the noise becomes higher and the resolution and precision is reduced. What voltage range is to be measured? Or another way to put this is what will the input voltage range be to the ADC? How small a voltage do you need to be able to measure (voltage value and not bits of resolution)?

Another question is with respect to communications interface. You have given both devices with SPI interface and with I2C interface. Which one is preferred?

Best regards,

Bob B

0 Arjun Singh over 2 years ago in reply to Bob Benjamin

Prodigy 20 points

Thanks for helping me out.

As per my requirement:

I have to measure current of the order of 1nA to 200uA with an accuracy of 0.5nA.

Voltage Measurement of the order of uV to 1V with an accuracy of 10uV.

I just wanted to know the best combination of 24 Bit ADC & 16 Bit DAC which are high speed so that the testing time do not increase.

Thanks & Regards

Arjun

+1 Bob Benjamin over 2 years ago in reply to Arjun Singh

TI__Guru** 113765 points

Hi Arjun,

As I'm only been given a block diagram I only see the voltage measurement. Do you also want to measure the current with the ADC? Also, you still haven't provided the information on how fast the measurement throughput requirement is?

Best regards,

Bob B

0 Arjun Singh over 2 years ago in reply to Bob Benjamin

Prodigy 20 points

Hello Bob,
Yes I will be measuring the current using ADC.
Data Rate > 2k-SPS will be good for my application.
I want 24 Bit ADC & 16 Bit DAC with I2C Interface.

Thanks & Regards
Arjun

0 Bob Benjamin over 2 years ago in reply to Arjun Singh

TI__Guru** 113765 points

Hi Arjun,

The only ADC with 2ksps output rate, I2C interface and is also 24-bit is the ADS122C04. I do not directly support the DAC devices, but you can start reviewing the available devices in the parametric search:

https://www.ti.com/data-converters/dac-circuit/precision/products.html#p84=16;24&p1918=I2C

You can start a new thread asking the DAC team for additional information on a specific device(s).

Best regards,

Bob B

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ADS122C04: Circuit Design for Low Current [nA] & Low Voltage [uV] Precise/Accurate Measurement.