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ADS4149: Question to Digital Interface

Part Number: ADS4149

Hi.

regarding ADS4149:

- In the data sheet pin 23 is marked "reserved". Is it ok if I connect it to GND?
- In my application I will use 4x ADCs, the ADCs are directly connected to the FPGA. What do I need the "Output Clock" for?
- For the input clock, "Figure 121" of the datasheet shows an AC coupling. 

I guess you would also need a 100 Ohm termination resistor, is it correct?

Thanks
Fred

  • Fred,

    You should not connect anything to pin 23.

    Output clock is used to help with clocking the data into the FPGA. The rising and falling edge of this clock is centered at the data valid time to provide the optimal setup and hold time in most cases. This clock can also be moved to assist with timing if needed. It is highly recommended to use this clock to latch the data.

    It is recommended to add a 100 Ohm termination resistor across the CLKP and CLKM signals. I would place this after the AC caps and as close as possible to the ADC clk pins.

    Regards,

    Jim