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ADS1271: CLK and SCLK relationship

Antonio Faggio
Expert 7890 points
Part Number: ADS1271
Other Parts Discussed in Thread: ADS127L11, ADS127L01

Hi,

My customer is dealing with the design of an acquisition card that uses the TI ADS1271 component.
Reading the datasheet it is reported that in the Frame Sync operating mode the CLK and SCLK must respect a specific relationship. Based on tables 10 and 11 it can be deduced that the frequency ratio must be 4 or 8 in the Low-Power mode we use. Looking at the ADS1271EVM eval board I realized that in Frame Sync mode the SCLK is a copy of CLK not respecting the timing described in the datasheet.
Is it possible to clarify if in the aforementioned mode we can use the ADC with the same signal on CLK and SCLK or is it necessary to respect the ratio of 4 or 8?
Thank you.,

Antonio

  • 0
    TI__Mastermind 46200 points

    Hello Antonio,

    In order to meet all datasheet specs, the customer should follow the requirements in Table 10, specifically t-SCLK=t-FRAME/64 for Low-Power mode.

    Many times, the EVM is developed before all specifications have been determined, and there are situations where the EVM may operate outside of the datasheet specifications.  We try to update the EVM operation in these cases, but this does not always occur.  I will do some additional research regarding this requirement and reply back with an update by end of business this week.

    The customer may also want to look at the latest generation ADC in this family, the ADS127L11.  This device has better performance, lower power, and can be operated using SPI to support data rates up to 1MSPS.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    TI__Mastermind 46200 points

    Hello Antonio,

    I discussed this with my colleagues.  The ADS1271 requires that t-SCLK=t-FRAME/64 for Low-Power mode when using Frame-Sync.  If you want to use SPI mode (which is the default mode for the ADS1271EVM), then f-SCLK can be set equal to f-CLK.

    As mentioned before, the customer may want to consider one of the newer generation products, such as the ADS127L11 (only supports SPI), or if frame-sync interface is preferred, then the ADS127L01 is also an option.

    Regards,
    Keith