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OP07C: how to use it to amplify pyranometer?

Michele Toriello
Prodigy 10 points
Part Number: OP07C
Other Parts Discussed in Thread: OP07

Hi there,

i'd like to use the OP07 to amplify the analog signal from an Apogee pyranometer (https://www.apogeeinstruments.com/content/SP-110-manual.pdf ).

I want to use a single +5V power supply and i need a gain of 100.

I'm trying to use the non inverting configuration as reported in datasheet with RG=10k and RF=100k but the Vout of the op07 is fixed to around 4V.

Any suggestion?

Thank's in advance. 

  • 0
    TI__Mastermind 23050 points
    Hi Michele,

    I'm not sure what your input is and what your expected output should be, but I believe there are two issues here:

    1) The minimum supply voltage for the OP07 is specified at +/-3V. This means you need 6V minimum between the positive and negative supply for proper operation. On single supply, you actually need +6V to have guaranteed datasheet performance.

    2) The OP07 is not a rail-to-rail output device, meaning you cannot expect to get an output voltage equal to your supply voltage. In fact, even in rail-to-rail devices, the output can still never get all the way to the rail! There is always some voltage that must be dropped across the output transistor to maintain bias. For the OP07, the typical output swing limitation for no load is about 1.5V away from the rail.