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Original question:

REF5020: Power management forum

REF5020: for shunt reference application

kiyo
Prodigy 10 points

Part Number: REF5020

Hi Team,

 I need + 2.95V relative to + 5V.

Therefore, I created a circuit by referring to the PDF below.(see figure.4)

https://www.ti.com/lit/eb/slyc147a/slyc147a.pdf

Based on this circuit, I performed transient analysis and DC analysis with PSPICE while changing the value of R1 and confirmed that the output became + 2.95V.

However, in order to confirm the characteristics when the power is turned on, I changed the power supply to Vpulse and performed transient analysis, but the result did not converge to + 2.95V.

I actually made a circuit of the real part and checked it, but it seems that the output voltage result changes depending on the resistance value of R1.

Am I doing something wrong?

best regards

 

  • 0
    TI__Intellectual 1735 points

    Hi Kiyo,

    I think the issue is here that there is an assumption that the voltage across the REF5020 will be 2V, where the thing here is that you are using it in a way that bypasses the internal gain structure of the bandgap reference voltage. This means that the voltage across it will be the bandgap voltage of 1.2V and not the 2V which is the gained up voltage.

    It appears based on your simulation vs tests, the simulation model is not provisioned for this sort of wiring.

    There are a couple things you can do:

    1. Stack up two of these parts if you are fine with 2.4V dropout.
    2. Do the circuit analysis based on the block diagram of the circuit below to determine if/how you can configure it for gain to 2V
    3. Use a shunt reference (https://www.ti.com/power-management/voltage-reference/shunt-voltage-reference/overview.html)

    Let me know what you think and I will try to help you along whichever of those options makes the most sense to you.

    -Tony

  • 0 in reply to Tony!
    Prodigy 10 points

    Hi Tony,
    thank you for reply.

    Stack up two of these parts if you are fine with 2.4V dropout.
    ->I need a reference voltage that follows the voltage of the 5V power supply, not the GND voltage.
    This configuration is most suitable for the circuit I am considering.

    Do the circuit analysis based on the block diagram of the circuit below to determine if/how you can configure it for gain to 2V
    ->It's difficult for me to determine from this block diagram
     
    Use a shunt reference (www.ti.com/.../overview.html)
    ->The shunt voltage reference  poorer temperature characteristics than the series voltage reference.

    I will consider if it can be solved in another way.

    Thank you Tony