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ADS7953: 1Msps @ 20MHz clock

Hans van de Laar
Prodigy 130 points
Part Number: ADS7953

Hi,

From the ADS7953, SLAS605C datasheet:

Looking at figure 1, device operation timing diagram.

After 14 clk cycles the acquisition phase is started. this is after 700ns @ 20MHz.

the acquisition phase has a minimum duration of 325ns. in total it takes 1.025us.

But at 1Msps I need to finish each sequence in 1us.

What I'm missing?

Regards, Hans

  • 0
    TI__Mastermind 25020 points

    Hello,

    The minimum acquisition time is 325ns.  Figure 1 shows that the acquisition time starts on the 14th SCLK rising edge, and the acquisition time does not end until the next frame at the next falling edge of CS. This time should be at least 6.5 SCLKs @ 20MHz. which is the 325

    The 14th clock is part of the acquisition time, thus it is 13* 50ns = 650ns

    This then gives 650ns (13 sclk cycles) + 325ns = 975ns, which means the device can meet the 1us cycle time.

    Regards

    Cynthia

  • 0 in reply to Cynthia
    Prodigy 130 points

    Clear. Thanks!