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ADS42LB69: Device usage with single channel; datasheet is unclear

radar
Expert 3550 points
Part Number: ADS42LB69

Hello,

I am trying to use the ADS42LB69 in DDR mode, but with only a single channel.  THe datasheet seems unclear to me as to how to do this; I thought I could just use the CTRL pins to disable the unused channel; but this table has be confused.  From the device datasheet, page 43, it shows:

which seems to state that I CANNOT power down channel B in DDR mode?!?!?  So, if i want to use a single channel in DDR mode, am I forced to use channel B; because A is the only one you can power down?  That's not intuitive; and doesn't seem to jive with the rest of the datasheet that shows the two channels as basic mirrors of one another- is this table just hosed up?

  • 0
    TI__Guru* 91947 points

    Radar,

    I am checking with the design team regarding this.

    Regards,

    Jim 

  • 0 in reply to jim s
    TI__Guru* 91947 points

    Radar,

    Since channel B’s clock is used by some of blocks in Channel A in DDR mode only, channel B cannot be powered down in this mode.

    Regards,

    Jim

  • 0 in reply to jim s
    TI__Expert 3550 points

    Jim,

    Okay, I probably didn't ask my question clearly enough; your explanation tells me one thing- I need to have channel B not powered down in order to run DDR mode; but it didn't get to the core of what I was really trying to ask, which was really; if i want to use DDR mode AND only a single channel; what's the lowest power way to do that?  That is, do I put the input on channel A and still have to have B powered up because I need the clocking as your answer dictates; or since I have to have B powered up can I put the input on B and somehow not have to have A powered up, and thus that would be lower power?  The Table 6 in the datasheet seems to show that '10' for CTRL2:1 would have channel A in powerdown and yet (possibly?) still support DDR mode; since there seems to be no mention of powerdown restrictions on channel A?

    So that's it; I am only using a single channel- what's the lowest power way to get to a DDR mode in that configuration?

  • 0 in reply to radar
    TI__Guru* 91947 points

    Radar,

    Yes, you can power down CHA and use CHB in DDR mode.

    Regards,

    Jim