AD7822 questions

I am implementing the AD7822 into a circuit. I was wondering if anyone can shed some light on my questions below.

A) The data sheet says 2 MSPS. But by looking at the timing diagram on page 17, the only way I can see to get that sample rate is to not change channels. And only if t13 does not apply at all if the channel is not changed from one sample to the next. The AD7822 has only one channel, so am I correct in assuming t13 does not apply and the remaining constraint for RD low to CONVST is t8+t3?

B) Can I tie RD permanently low? The datasheet implies no in a round about way. I would prefer to not let the outputs go into tristated hi Z.

C) t10 is quite short (5ns). Has anyone had better luck in finding a latch with decent margin to use this device in stand alone mode?

Thanks

AdvRdr

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    •  Analog Employees 
    on Jul 15, 2011 8:34 AM

    Hi AdvRdr,

    A) Yes, the AD7822 is a 2MSPS ADC with only one channel. For this reason t13 does not apply - as it is only required to satisfy this timing when channel hopping.  Yes, the timing constraint from RD low to CONVST is t8+t3.

    B) Yes, RD can be tied permanently low.

    C) Is is possible for you to latch while EOC is low?

    Regards,

    ClaireL.

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  • 0
    •  Analog Employees 
    on Jul 15, 2011 8:34 AM

    Hi AdvRdr,

    A) Yes, the AD7822 is a 2MSPS ADC with only one channel. For this reason t13 does not apply - as it is only required to satisfy this timing when channel hopping.  Yes, the timing constraint from RD low to CONVST is t8+t3.

    B) Yes, RD can be tied permanently low.

    C) Is is possible for you to latch while EOC is low?

    Regards,

    ClaireL.

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