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Original question:

ADS131M02: could customer use the clock from MCU as the clock source for ADS131M02?

ADS131M02: what differences are in different CLKIN

Allen Huang
Prodigy 60 points
Part Number: ADS131M02

HI,

At High-resolution mode, CLKIN frequency range can be 0.3~8.4MHz. But the Frequency of CLKIN for test conditions in datasheet are all 8.192MHz.

Pls describe what differences in below conditions:

1. CLKIN=8MHz

2. CLKIN=8.192MHz

Is it related with noise rejection?

Is it related with ADC conversion accuracy?

  • +1
    TI__Guru 57306 points

    Hello Allen,

    Thank you for your post. 

    Most of our characterization is conducted using nominal clock frequencies and data rates. When you scale the clock frequency, the modulator frequency and the output data rate will scale by the same factor. As the data rate reduces, you will also reduce the bandwidth of the digital low-pass filter. This can help improve the noise performance slightly, but the SNR and ENOB will remain largely the same.

    A more significant improvement in noise performance can be achieved by increase the oversampling ratio (OSR) because this increases the averaging in a delta-sigma converter.

    Reducing the clock frequency also has the effect of saving some current consumption. Not all circuitry inside our devices depend on a clock, so the power scaling is not as obvious as a SAR ADC.

    Best regards,

    Ryan