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Guard on ADG1402 analogue switch


Is pin 2 on your ADG1402 analogue switch internally connected or can it be used to guide a guard ring around pin1?

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  • I like it very much with the ADG1401/1402 that the one NC pin is pin 2 so it can be used for routing a guard ring around pin 1.

    I would have loved it, though, if the second NC pin would have been pin 7 instead of pin 5, so it would have been possible to route another guard ring over an NC pin for signal pin 8, too.

    It shouldn't have been too difficult to make the wirebonds for Vss and IN a little skewed and bond them to pins 6 and 5 instead of pins 7 and 6.

    Also, for layout routing it is always nice to have NC pins that are not at the end of the pin row, because you can use them for routing if the technology does not allow to route between adjacent package pins (depnding on pitch of the package pin and minimum track width and clearance of the PCB technology).
    NC pins at the end of the pin row are more or less useless.

    Maybe someone could communicate this to the IC designers.
    And also if there are input pins that may benefit from pull-ups, it might be nice to implement a (very) weak pull-up in the IC.
    Just the ADG1401/1402 are ICs that would profit from such an integrated pull-up.
    If they are used with higher positive supply voltages (like +12 or +15V), standard logic levels at IN lead to higher than necessary Idd (around 55µA), which are not that easily avoidable.
    With a weak pull-up of a few microamperes, an open collector or open drain transistor would be able to provide close to VDD at IN and the quiescent VDD current could be negligible.

    Just my 2 cent...