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Original question:

OPA547: TO-220-7

OPA547: TO-220-7

user83215
Prodigy 80 points
Part Number: OPA547


trying to get the output to be -40V. How could I use the OPA547 to get this output using (V-) set to -48 and (V+) set to GND.

Thanks

  • 0
    TI__Guru* 93105 points

    Hi user83215,

    It should be doable with the OPA547. Please answer the following questions:

    1. What voltage level is the output load going to be referenced to i.e. -48 V, Ground (0 V), or some other voltage in between?
    2. What exactly is the output load?
    3. How much current does the OPA547 need to provide to the load?
    4. What input voltage do you intend to apply to the OPA547 input circuit?
    5. Are there any other things that need to be considered?

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 80 points
    Resistor load. current out max is 0.2A. reference would be to GND.(ground)
  • 0 in reply to user83215
    TI__Guru* 93105 points

    Hi user83215,

    I am not sure about exactly what you need from the OPA547 circuit, but based on the information you provided I developed the circuit shown below.

    The power supply provides -48 V relative to ground. V+ is at 0 V and V- is at -48 V. The resistive divider consisting of R1 and R2 divides the -48 V, to -40 V  which is applied to the OPA547 non-inverting input. The OPA547 is configured as a gain-of-one buffer (+1 V/V) so the output should be very close to -40 V. RL is connected to ground and the output current flows through it and is sunk to the -48 V Vs line through the OPA547 output. When the OPA547 output is at -40 V a 200-ohm RL results in an output current of 200 mA.

    I have attached my TINA Spice circuit in case you want to try some simulations.

    OPA547_ neg_sply_01.TSC

    Make sure you observe the OPA547 thermal considerations explained in the Applications Information, starting on datasheet Pg. 8.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    TI__Genius 11135 points
    user83215

    We haven't heard back from you so we assume this answered your questions. If you need more help just post another reply below.

    Thanks
    Dennis