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ADS1261: Reconstructing sine waves of 1k, 10k, & 1MHz.

Sebastian Carillo
Prodigy 10 points

Part Number: ADS1261EVM
Other Parts Discussed in Thread: ADS1261

Tool/software: TI C/C++ Compiler

Hello,

I got the ADS1261EVM board and I successfully downloaded and installed the required drives and program to operate the board. I am trying to input and reconstruct using the Delta Signal application the following:

 sine wave at different frequency (i.e 1k, 10k, 1M, etc.) at a relatively small amplitude (i.e 10mV VPP and 5mV VPP).

I connected the signal generator the following way:

The positive input ---> to AIN7/AIN5

The negative input ---> to AIN6/AIN4

and I configure the following registers:

Data Rate to 400SPS

MUXP AIN7

MUXN AIN6

PGA  GAIN 64 V/V

Everything else remains as default, but I can't get a proper reconstruction, and I keep getting a fault error "PGA Low Alarm" 

Can someone please help me accomplish a proper set up?

 

  • 0
    TI__Mastermind 44780 points

    Hi Sebastian,

    Welcome to the TI E2E Forums!

    What you're trying to do is okay, but do keep in mind that the ADS1261 has an integrated digital filter and depending on your configured data rate you may have issues trying to reconstruct waveforms with frequencies above a few kHz. Please see figures 56-61 in the datasheet for examples of the digital filter response.

    Regarding the "PGA Low Alarm", this sounds like an issue with the common-mode voltage of the signal that you are trying to apply to the ADC inputs. Please refer to Equation 5 of the datasheet, and utilize the ADS1261 Excel Calculator (found here: www.ti.com/.../sbac200) to ensure that your input signal amplitude and common-mode voltage will work. You will need to reference the signal generator to the same ground potential as the ADS1261EVM.