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ADS5294: ADS5294 SYNC pulse timing

Part Number: ADS5294

Hi,

Hi,

We are using a single ADS5294 and I am planning on using decimation  /2  or /4 ( possibly by 8)

Regarding the ADS5294 data sheet, Figure 60:"Synchronization pulse timing"

Q1: the data sheet refers to a single sync pulse, but Figure 60 shows a periodic sync pulse train. Which one is it, single SYNC pulse or a pulse train?

Q2.Figure 60 shows the sync pulse frequency as ADC_clock/ 2. Does Figure 60 refer to  "Decimate by 2"  case only or it is for all decimating cases /2, /4 ,/8. What would the sync pulse look like if I want decimation by 4 or by 8?

Q3: The rising edge of the SYNC pulse is shown to be between  -1ns < td  < tclk/2 in Figure 60. That would mean the sync pulse can not be a free running sync pulse train but it has to be synced to the ADC clock?

Thanks

  • Hi, 

    Thank you for your interest in ADS5294. My answers for your questions are - 

    Q1. SYNC is primarily a pulse. But it can also be a pulse train with a pulse repetition frequency depending on your application (say 1kHz or 10kHz). Figure 60 is a bit misleading, apologies. 

    Q2. Yes, Figure 60 will only work for decimate by 2. If you want to use decimate by 8, the time period of the pulse train must be greater than or equal to 8*tclk. 

    Q3. Yes, the SYNC pulse train must be synced to the ADC clock.

    Thanks,

    Karthik

  • Thanks Karthik.

    Q3': Regarding Q3: when the SYNC pulse is synchronized to the ADC clock, the SYNC rising edge  the condition " -1ns < td < tadc_clk/2"  should be met for all decimation factors /2, /4 /8 correct?

    Another related Question:

    Q4. you said 

    If you want to use decimate by 8, the time period of the pulse train must be greater than or equal to 8*tclk.

    Can I use this SYNC clock period for decimate by 8, to decimate by 2 and 4 as well or i have to have some sort of a sync pulse multiplexor to choose amongst 3 different sync pulse trains /2 , /4 and  /8?

    Thanks

  • You can use the SYNC pulse train used for decimate by8 for decimate by2 and decimate by4 as well. You don't need a multiplexer. 

    Regards,

    Karthik