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OPA522

Other Parts Discussed in Thread: OPA552, OPA192, OPA564, OPA170

Good morning,

I used OPA552on my card with the following characteristics:

Vcc  9 to 25Vdc

Gain x10, non-inverting

Vin 0.5Vdc with Vout 5Vdc or Vin 1.25Vdc with Vout 12.5V or Vin 2Vdc with Vout 20Vdc 

Iout 200mA

The VCC changes along with the selection of the VIN.

I had no problems but rechecking the data sheet I understand the minimum Vin = V- + 2.5V .

If so should be the input is not polarized is then VOUT wrong .

What I did not understand?

Davide Gandolfi

  • Hello Davide,

    The OPA552 has a common-mode input voltage (CMV) range that extends from (V-) + 2.5 V to (V+) -2.5 V. This is the linear input voltage range. If your your V- supply is 0 volts, then the minimum CMV voltage that should be applied to the OPA552 non-inverting input is +2.5 V. If you apply an input voltage that is less than +2.5 V to the non-inverting input, the linearity of the amplifier circuit cannot be assured and the output signal may worsen as the input CMV is driven further towards 0 V.

    If you don't need the 200 mA output of the OPA552, there are other op amps that have a low-end CMV that goes down to 0 V. An example of this is OPA192:

    It doesn't deliver as much output current as the OPA552, but its CMV range extends from (V-) - 0.1 V to (V+) + 0.1 V.

    Regards, Thomas

    PA - Linear Applications Engineering

  • Hello Thomas,

     thank you for the answer.

    I use OPA552 like a precision voltage regulator for external sensors that my board acquires, like Weastone bridge, loop 4-20mA, extensimeter and more other.

    The OPA192 output current is very low for my application.

    I try to search the TI site for an alternative.

    Davide

  • Hello Davide,

    If you have room on your PC board, The OPA564 has a CMV range that extend from (V-) to (V+) - 3 V. It is rated with a 1.5 Amp dc output current; which is probably overkill for your application, but worth considering if you don't find another suitable high output current op amp.

    You can find the OPA564 datasheet here:

    Regards, Thomas

    PA - Linear Applications Engineering

  • Davide,
    Did you find an acceptable solution?
    ~Leonard
  • Hello Leonard,

    the bridge solution is OPA170 buffered with LT3092.

    This solution is temporary untill new board version.

    Thank for yuor interesting and sorry for my english

    Kind Regards

    Davide Gandolfi