ADS1205: Concern regarding the schematic

Neha Agarwal

Part Number: ADS1205

Hi,

I am working on developing a DCDC converter and I needed some help with the schematic for ADC part.

Could you please have a look at the schematic below and let me know if the ADS1205 can be operated in the way I have done.

Thanks,

Neha

over 3 years ago

0 Alexander Smith over 3 years ago

TI__Guru 60392 points

Hi Neha,

Can you please share some background as to why you selected this part and what the intention of the measurement is?

What do you plan to interface the output of the ADS1205 to?

The output voltage of your OPAMP is directly connected to ground, which will certainly cause problems.

0 Neha Agarwal over 3 years ago in reply to Alexander Smith

Prodigy 80 points

Hi Alexander
I chose the opamp to scale the output voltage to a value between 0 and 5V and so that the delta sigma modulator can convert it into digita; signal

The output from ADS1205 is sent to microcontroller
The output is connected to an RC filter, is that going to be a problem?

0 Alexander Smith over 3 years ago in reply to Neha Agarwal

TI__Guru 60392 points

Hi Neha,

Directly connecting the gain resistors of the OPA to 800V will likely cause issues and the output of the OPA is connected to AGND after the RC filter.

The ADS1205 produces a delta-sigma bit stream where the 1's and 0's density is proportional to the input voltage that is meant to be fed to a sigma delta filter module. Connection to an RC filter will not produce a high quality measurement.

Does your measurement have an isolation requirement? This may be needed to protect other circuitry or humans from being exposed to the 800V rail.

I recommend taking a look at our collateral for some circuit examples and more background on how to use these devices:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1164993/faq-isolated-data-converter-collateral-overview