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ADS131E04: Disable External Clock Source

stenzer
Prodigy 210 points

Part Number: ADS131E04
Other Parts Discussed in Thread: ADS131A04

Hi,

I'm planning to to use ADS131A04 in a low power system. To minimize the power consumption I have to disable the external clock source. Are the ADC registers kept "save",  when the clock is disabled, after setting the ADC in Standby Mode (STANDBY) (keeping the ADC itself powered)?

Because if the registers have to be set agein after disableing/enabling the clock, I would save more energy by disabling the whole ADC.

BR

Stenzer

  • 0
    TI__Guru 68916 points
    Hello Stenzer,

    Thanks for your post.

    As long as power supplies remain enabled, the register settings will be saved when the device enters Standby Mode. You can also disable the external clock as well.

    Let me know if you have any other questions.

    Best Regards,
  • 0 in reply to Ryan Andrews
    Prodigy 210 points

    Hi Ryan,

    thank you for the reply, so it works as I expected.

    Are there any application notes regarding anti aliasing filters? I have to sample four DC values simultaneously, to achieve a low cut-off frequency large capacitance and resistance values (1st order LPF) are needed. I know large resistance values can be critical for a Delta-Sigma  ADC.

    BR

  • 0 in reply to stenzer
    TI__Guru 68916 points

    Hi Stenzer,

    For DC applications, it is not necessary that you make the cutoff of your antialiasing filter so low. Depending on the data rate and digital filter architecture, the ADC's bandwidth will already be significantly limited. The main goal of the antialiasing filter becomes to attenuate the higher out-of-band noise, especially near the ADC modulator frequency. The modulator frequency is where the digital filter returns to unity gain and allows for signals to alias into the passband.

    The cutoff for the antialising filter should be placed at least two decades before the modulator frequency. A first-order filter will provide -40dB attenuation in that case. If more attenuation is desired, you either need to decrease the cutoff frequency further, or use a higher-order filter. Make sure that the cutoff frequency you choose does not interfere with your signal bandwidth of interest.

    Below is a link to Part 1 of a three-part blog series that I wrote on antialiasing filters, as well as a training video in on aliasing in our Delta-Sigma ADCs training series. Enjoy!

    Best Regards,