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Description: The TL431 is a three−terminal programmable shunt regulator diode. This monolithic IC voltage reference operates as a low temperature coefficient zener which is programmable from Vref to 36V with two external resistors. They exhibit a wide operating current range of 1.0mA to 100mA with a typical dynamic impedance of 0.22 ohms.

The characteristics of these references make them excellent replacements for zener diodes in many applications such as digital voltmeters, power supplies, and op-amp circuitry. The 2.5V reference makes it convenient to obtain a stable reference from 5.0V logic supplies, and since the TL431 operates as a shunt regulator, it can be used as either a positive or negative voltage reference.


  • Programmable Output Voltage to 36V
  • Voltage Reference Tolerance: ±0.4%, Typ @ 25°C (TL431B)
  • Low Dynamic Output Impedance, 0.22 ohms Typical
  • Sink Current Capability of 1.0mA to 100mA
  • Equivalent Full−Range Temperature Coefficient of 50 ppm/°C Typical
  • Temperature Compensated for Operation over Full Rated Operating Temperature Range
  • Low Output Noise Voltage
  • Pb and Halide−Free


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Customer Comments

  • You can find a free “tool” on the website that can calculate the resistor values for you (Excel sheet with a Macro).

    I created a quick screenshot of the tool in action which also includes a demo circuit of how to use it.

    • A calculator in a spreadsheet, really? Is this the 1990s?? Today you make this in Javascript.

      • It was written in 2005 and still runs today with no modification. Most websites from 2005 are all sorts of broken or obsolete. (Suppose they’d written it in Flash…)

        Conclusion: Excel is a more stable environment to write simple tools in.

    • Very cool! Thanks!

  • I need a stable reference voltage for a temperature monitor I am building using the TMP36 analog temp sensor and an Atmega328 self-built Arduino clone. Is something like this a good choice for that application?

    • Little late but could be useful: I did use this for a TMP36 project based around a PIC16F1828 and didn’t have any problems.

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