ADG884 Threshold voltage on IN1/IN2

I selected the ADG884 to switch analog signals which have a 0-5V range (hence I'm powering it from the same 5V rail) using a logic signal that has a minimum high voltage of 2.5V as the ADG884 data sheet says that when powered from 5V the digital inputs only need 2.0V to switch.

So I've had 20 prototypes built, but none of them switch to the A inputs with a logic input of 2.5V (checked and verified using a scope and a DVM) - the B inputs are always routed to the D outputs.

So what's the problem? What am I missing/doing wrong?

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  • What I don't understand is that the ADG884 data sheet says the threshold voltage on the logic input is 2.4V maximum, but I'm applying 2.5V and it doesn't switch - so that suggests that either the data sheet is wrong or something strange is going on.

    I'm not switching the logic inputs dynamically so a scope shot would be really boring!

    The logic signals are driven from a device on a 3.3V rail so to apply anything more than 2.5V would mean cutting tracks - something I'm trying to avoid doing.

    I've requested some samples of the ADG787 to see if that behaves any differently.

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  • What I don't understand is that the ADG884 data sheet says the threshold voltage on the logic input is 2.4V maximum, but I'm applying 2.5V and it doesn't switch - so that suggests that either the data sheet is wrong or something strange is going on.

    I'm not switching the logic inputs dynamically so a scope shot would be really boring!

    The logic signals are driven from a device on a 3.3V rail so to apply anything more than 2.5V would mean cutting tracks - something I'm trying to avoid doing.

    I've requested some samples of the ADG787 to see if that behaves any differently.

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