ADA4092-4 differential input voltage

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.

We are also promoting this new tool for instrumentation amplifier. It may help you to see instantly your hexagonal plot (Common mode voltage vs Output voltage) which are dependent on your settings. It will also gives you a recommended Inamp products that are suited based on your requirements..

Here is the link: Instrumentation Amplifier Tool - Common Mode vs. Output Voltage (Diamond Plot)

We will appreciate if you could also give us feedbacks regarding this tool.

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