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OPA2670: Split Power Supply & Common Mode Range

Part Number: OPA2670

Hi,

I'm going to use OPA2670 with +6V and -6V supply. According to the "Pin Configuration" in the data sheet page 2, #4 pin is named "GND". 

 Q1 : In a case of -Vs=-6V, +Vs=+6V, is this "GND" pin voltage 0V generated by OP2670? 

 Q2 : If +Vs=+7V and -Vs=-5V, what voltage does the GND pin appear, 0V, +1V, or other voltage?

 Q3 : What Is the reference voltage of A0 and A1 ?  Does A0=1 mean (-6V+2)V or (GND pin voltage +2)V? 

 Q4 : Common Mode Input Range SPEC is described as +/-3.5V min. Is this common mode voltage referred to GND pin voltage? 

 Q5 : I need to use just one OPamp. I don't think all pins of other OPamp are left open. What should I do for other OPamp? 

  

  • Hello user552018,

    1 & 2) The GND pin is an input which you should supply to the OPA2670.
    3) Pins A0 and A1 are referenced to the GND pin, so GND+2V.
    4) The common mode input range is referenced by the mid-supply of the amp.
    5) It is recommended that you connect your unused amplifier in a buffer configuration, and connect your non-inverting pin to your mid-supply.

    Best,
    Hasan Babiker

  • Hi and welcome to E2E,

    1. No, 0V is not generated by OPA2670.
    2. It will appear as floating if it is not tied to ground.
    3. The latter. GND is the reference for the logic pins.
    4. No, it is not with respect to the GND pin. It is the maximum swing possible if the input is referenced to mid-supply, which is only ground for Vcc=Vee.
    5. You should configure it for unity gain to prevent the unused amplifier from oscillating. Use a feedback resistor of around 750 ohms.

    Best regards,

    Sean