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LMC6482: How to Terminate the Inverting Terminal of Unused Voltage follower with single supply -Opamp LMC6482

Part Number: LMC6482

Hi,

 

 I am using LMC6482 op-amp in a Voltage follower configuration (with inverting terminal connected to output ). What will be the voltage at the output when Non inverting terminal is pulled down with 10K resistor. I am using 3.3V single supply .

I have interfaced the output of this op amp LMC6482 to the input of ADC (Processors Internal ADC)

  • Hi Mohamed,

    In a single supply configuration, grounding the input is going to saturate the output due to the output swing limitations of the op-amp. For an unloaded LMC6482, the typical output will be around 100mV, but could be as high as 240mV across temperature.

    Regards,

    Zak Kaye
    Precision Amplifiers Applications 

  • In reply to Zak Kaye:

    Hi Zak Kaye,

    Thanks for your reply.

    I am using Dual Pack Opamp with 1 Opamp configured as Voltage follower and another Opamp as Voltage Follower with Inverting Terminal Pulled down with 10K.

    As per your Answer the Output of Opamp shall saturate (3V approx.). Is this can cause Opamp to damage ?(With 1 Opamp working and another Unused with above said configuration) due to increased current flow ?

    Thanks

  • In reply to Mohamed Shali:

    Mohamed,

    If you are pulling the non-inverting input of the buffer to ground with a 10kOhm resistor, then the output is going to saturate towards the negative supply (ground) and you could expect the output to be around 100mV. This will not cause damage, but it is generally better practice to terminate unused channels such that they are still operating within their linear region. Otherwise, the saturated channel of the IC may consume more than the specified current and is more likely to interfere with neighboring channels. If you have the space for it, I would suggest adding an additional resistor and instead biasing the input to mid-supply. Using large value resistors will minimize the current consumed in this divider.

    Regards,

    Zak Kaye
    Precision Amplifiers Applications