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ADA4092-4 differential input voltage

Hello


Please let me know about overvoltage protection (OVP) of ADA4092-4.

Datasheet P. 6 tabel5 absolute maximum rating says below.
Input Voltage: Refer to the Input Overvoltage Protection section
Differential Input Voltage: ±VSY

What is the difference between input voltage and differential input voltage ?
Our customer asks if above means that OVP does not work when differential signal input is used,
because customer uses ADA4092-4 in below condition.

Operated condition
5V single supply
Input signa: 2.5V +-2.5V differential input

(-10~+10V overvoltage protection is needed )

Regards,
Terumasa

  • Hi Terumasa,

    What do you mean by +/- 2.5 differential input signal? What is your configuration? Can you show us your schematic?

    Best regards,

    Emman 

  • Hello Emman

    Schematic is attached.

    Customer makes instrumental amp using 3 amps of ADA4092-4

    Input signal is common 2.5V, signal +-2.5 (2.5V+-2.5V).

    Input is not differential input in attached circuit but  we do not know the difference of OVP  between input signal and differential input in Datasheet P. 6 tabel5 absolute maximum rating.

    So, we concern if table 5 means that OVP is not worked in any condition.

    Could you give me your advice difference betwen  input signal and differential input in Datasheet P. 6 tabel5 absolute maximum rating ?

    Regards,

    Terumasa

  • Hi Terumasa,


    The input voltage on the absolute maximum ratings table refers to the voltage on either one of the inputs ( +Vin, -Vin) while the Differential Input Voltage is the difference between the two inputs (+Vin minus the - Vin). Also according to the product owner of this part, The differential input voltage limits the maximum voltage between the two input pins so that they don't exceed the power rails. OVP does not apply to this. The OVP refers to the maximum voltage of any one input above the Vee supply.

    I am not totally sure if I understand your input signal but make sure that it is always within the input voltage range of the amplifier.

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    Best regards,

    Emman

  • Hi Terumasa,

    With your set up conditions, it clearly violates the absolute max rating for the differential input voltage stated on the datasheets and we really do not recommend that. However, based on figure 48 and 49, It shows that there is a differential protection diode and a series of 5 kohms resistors across its input. We are looking for a possibility that it may work, and maybe the datasheets just become too conservative. But I still need to confirm it to the designer or even measure it on the lab to verify this. This may take a one or two weeks but I will get back to you as soon as I can.

    Best regards,

    Emman

  • Hello Emman

    Thank you for your advice.

    Please let me confirm if my understanding is correct.

    For example, ADA4092-4 is used at below overvoltage input condition in attached voltage folower.

    Input: Overvoltage +15V

    Supply: SIngle 5V supply

    In this case, differential input voltage is +Vin -  -Vin = 15V -5V =10V.

    10V is above limitation of absolute maximum rate of differential input voltage  ( within +-Vsupply = 0~5V).

    So, Overvoltage above supply rail can not be protected in this case ?

    Is it correct ?

    Please let me know your advice

    Regards,

    Terumasa

  • Hello Emman

    Thank you for your prompt reply.

    I wait for your reply.

    Regards,

    Terumasa

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