TL431 Shunt Regulator Resitor Values

Discussion in 'The Projects Forum' started by Baterka274, Jan 6, 2016.

  1. Baterka274

    Thread Starter New Member

    Oct 2, 2015
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    0
    Hello,
    I have got a circuit which works as high current shunt regulator and indicator of battery status (for stethoscope). Input voltage from battery is 9V and output voltage 5V. I have finished my indicator yet, but I am not sure about regulator and his values. Can you help me with values of resistors in this regulator (R16, R20, R22)? I use diode TL431 in this circuit.
    Thank you very much
    Tom
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    How about changing the title to something more descriptive. Like, "TL431 shunt regulator question"
     
  3. DickCappels

    Moderator

    Aug 21, 2008
    2,650
    632
    R16 and R22 need to be the same value for a 5 volt output. Each can be 10k ohms.

    As for R 20, how many milliamps is the load on your +5 volt output?
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
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    You really don't need VR2 to regulate the voltage for the led.
    You can just set the LED current with a resistor.
     
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    @ronv : He is using the left TL431 as a low voltage detector that lights on low battery voltage; not using it to regulate the current through the LED.

    @Baterka274 Dobry Den.
    Answer Dick's question about the load current...
     
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