Tool/software:
Hi team,
I have a question regarding the input voltage range of the OPA2187.
On page 7 of the datasheet, under “INPUT VOLTAGE RANGE,” the VCM (common-mode voltage) maximum is listed as (V+) - 2. Is this correct?
My understanding is that while this operational amplifier has a rail-to-rail output, its input is not rail-to-rail, resulting in a narrower input range. Is this understanding correct?
Best regards,
Tomo Akiyama
Hi Tomo-san,
On page 7 of the datasheet, under “INPUT VOLTAGE RANGE,” the VCM (common-mode voltage) maximum is listed as (V+) - 2. Is this correct?
Yes, this is correct. OPA2187 is RRO op amp, but not RRI type. The input Vcm is shown in the table below.
while this operational amplifier has a rail-to-rail output, its input is not rail-to-rail, resulting in a narrower input range.
Not all op amp applications require RRIO type. In this case, OPA2187 is RRO which it can swing output voltage close to supply rails. If the OPA2187 is configured with a gain (especially higher gains), then it is not necessary to use RRI op amp type.
If you are using the OPA2187 as a buffer, then there is certain input limitation per the input Vcm requirements, unless you increase the positive supply rail.
If you have other questions, please let us know.
Best,
Raymond
