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ADG5404 cross talk?

hello,

ive some problem with my designed multiplexer card, i attach the schematic, see adg5404.jpg.

the address is set to 0:

if i switch +24V on out_1 and measure the results on out_mplex_1 and out_mplex_2,

now i get some heavy spark on the out_mplex_2, see osci_1.jpg.

the address is set to 1:

if i switch +24V on out_1 and measure the results on out_mplex_2 and out_mplex_3,

now i get some little spark on the out_mplex_3, see osci_2.jpg.

 

 

is this an design error?

why is the spark on out_mplex_2 such high?

some hints for me?

 

thanks a lot

attachments.zip
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  • Hi Nico,

    That's great that helped.  I think this would point towards the speed of the logic transition when using the 100k compared to the 10k affecting the charge injection mechanism.  The logic input is into a high impedance buffer with associated capacitance, see the equivalent circuit for the charge injection mechanism. If using pull up/down resistors I would typically use 10kohm resistors on our switch evaluation boards.

    Regards,

    Eric.


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  • Hi Nico,

    That's great that helped.  I think this would point towards the speed of the logic transition when using the 100k compared to the 10k affecting the charge injection mechanism.  The logic input is into a high impedance buffer with associated capacitance, see the equivalent circuit for the charge injection mechanism. If using pull up/down resistors I would typically use 10kohm resistors on our switch evaluation boards.

    Regards,

    Eric.


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