input range of the FET input on the AD8033 / AD8034

Hi,

For the Input Range, the datasheet provides typical value only.
This typical value is characterization from number of samples and not being tested in final test for each part.
Basing from table 1 to table 3, the input range is typically from -Vs to (+Vs - 3V).

For the drift, the spec table is specified only @ 25 degC and not across temp.
We could not guarantee the same range at other operating temperature especially that the input voltage range is given only in typical value.

What is the supply range of your application and what range is your intended input?
Hence, the higher the supply range, the wider the input voltage range.

Also, is it to okay to share your application?
We might offer some parts that is more suitable.
We have some rail-to-rail input amplifiers that may accept wide range of input.

Thanks and regards!

This device is used in the analog input part of the instrument.
Although it is VS-3V, in the data sheet table 1, it is -5V to 2.2V (that is, VS-2.8V) under the condition of VS = ± 5V.
Is this a typo?

Since it was 2.2V, I am using it up to 2.0V considering the margin 0.2V, but I inquired because there were many 2.0V or less in the lot I purchased recently.

I made an inquiry to determine whether the specifications should be reviewed based on the yield.

(Since it is currently used in mass production, no other proposal is required.)

Hi,

Yes, it seems to be odd since 12V supply is upto 9V input and 5V supply is upto 2V input but maybe this is the typical range that been captured during characterization.
But again, this is only typical and not tested for each released part.
You may want to consider higher margin to ensure you are in the operating range.

Thanks and regards!

I understand that 2.2V is a typo error.

＞You may want to consider higher margin to ensure you are in the operating range

I inquired about Q1 and Q2, which I wonder how much margin should be secured.

Is there a reference value?

Or, in the shipping test, some parameters such as offset are measured with the common voltage at 〇〇.
Could you give me information such as that it is okay for the voltage above 〇〇 at room temperature?

Hi,

Since it is typical, we could not guarantee it. It may not the same from the other parts that you have on hand.

Theoretically, the FET input range should be -Vs to (+V - 3V).
In addition, from Input Drive section, page 16 of data sheet, the part can accept higher common mode, above from the specified FET Input Range.
The part has the feature of switching the input stage from FET to BJT (please see simplified schematic, figure 53) but please consider the change in performance especially on bias current and offset voltage when part is operating with BJT input (please refer to figure 32 and 35).

Hope this helps.

Thanks and regards!