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Start Up Time For Analog to Digital Converters (ADC)

Darren O'Connor
Prodigy 70 points
Other Parts Discussed in Thread: ADS5463-SP, ADS5444-SP

Hello,

I have a low power, high-speed application in which I need to sample at 250 MHz and want to conserve power by shutting off the voltage to my ADC until there is a signal of interest. I'm wondering, with the ADS5444-SP and the ADS5463-SP, how long after the proper voltages are applied for supply power that the ADC samples will be correct? If your answer includes the pipeline delay for the devices, please indicate this is the case. If these parts have a start up time beyond 100 nS, are there any other space qualified parts capable of 250 MHz sample rates that have faster start up times?

Thanks in advance,
Darren O'Connor
Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder
  • 0
    TI__Expert 8895 points

    Hi, Darren

    Though this is the same question for the similar question to previous one, please refer to my answer below. I'll discuss this issue with designer of this device and get back to you.

    ADS5463 has internal power-up time, 200us, from power supply and 3.5 clock cycles of data latency.  ADS5463 requires a sequence of power-up as below and also you can refer to the page 37 of datasheet for more information.

    - Power up both AVDD3 and DVDD3 at the same time (best scenario), or

    - Keep the voltage difference less than 0.8V between AVDD3 and DVDD3 during the power up (0.8V is not a hard specification - a smaller delta between supplies is safer).

    Thanks,

    KW

  • 0 in reply to KW Nam
    TI__Expert 8895 points

    Hi,

    When no power is applied, all of the references are off. The reference have large RC time constants for noise suppression, so these all have to charge up when power is reapplied. This takes up to 50us for the guaranteed SNR of sampled data.

    Thanks,

    KW