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ADG4612 output problem

Dear Madam/Sir,

I am using the ADG4612 switch in my design. I connect Vdd to 3.3v and Vss to 0v

However I am getting false outputs in those two cases:

- when enable is off and Vin > Vdd+Vt I get an output equal to Vin/2 while i should get nothing

- when enable is on and Vin < Vdd+Vt it works fine however when Vin is higher, I get the same behavior as in case one.

Could you please help me with that issue.

Thank you in advance.

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  • Hi,

    When your analog input exceeds Vdd by about 1.2V the switch turns Off and there is a high impdeance across the switch.  The output is Open circuit so it should fall-off to GND.

    What load is connected to the switch output?

    Can you also test when EN is Off and Vin <Vdd to check if part is turning OFF correctly in Normal Mode?

    (It sounds like part is not fully off)

    Have you measured this problem on just one part? Can you try new parts?

    See the attached ciruit note, figure 6 shows scope plot of the part powered with Vdd=3.3V and a 6Vpp sine-wave applied to the input.

    http://www.analog.com/static/imported-files/application_notes/AN-1219.pdf

    Rgds,

    Theresa.

Reply
  • Hi,

    When your analog input exceeds Vdd by about 1.2V the switch turns Off and there is a high impdeance across the switch.  The output is Open circuit so it should fall-off to GND.

    What load is connected to the switch output?

    Can you also test when EN is Off and Vin <Vdd to check if part is turning OFF correctly in Normal Mode?

    (It sounds like part is not fully off)

    Have you measured this problem on just one part? Can you try new parts?

    See the attached ciruit note, figure 6 shows scope plot of the part powered with Vdd=3.3V and a 6Vpp sine-wave applied to the input.

    http://www.analog.com/static/imported-files/application_notes/AN-1219.pdf

    Rgds,

    Theresa.

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