Diodes Incorporated

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Low Knee Current 2.5/2.495V Adjustable Shunt Regulator

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The AP431S/AP431SH is a 3-terminal adjustable shunt regulator with guaranteed thermal stability over a full operation range. It features sharp turn-on characteristics, low-temperature coefficient and low output impedance, which makes it ideal substitute for Zener diode in applications such as switching power supply, charger and other adjustable regulators.

The AP431S/AP431SH has the same electrical specifications as the industry standard 431 except that it features a low minimum cathode current for regulation. The typical value of 50μA makes the parts ideal for very low power dissipation applications.

The output voltage of the AP431S/AP431SH can be set to any value between VREF (2.5V/2.495V) and the corresponding maximum cathode voltage (36V).

The AP431S/AP431SH is offered in two grade initial voltage tolerance at +25°C, 0.5% and 1%.

This IC is available in 3 packages: TO-92 (Ammo Packing), SOT23 and SOT89.


  • Low Minimum Cathode Current for Regulation: 50μA (typ.), 100μA (max.)
  • Programmable Precise Output Voltage from 2.5V/2.495V to 36V
  • High Stability Under Capacitive Load
  • Low Deviation of Reference Voltage Over Full Temperature Range: 11mV typical (-40°C to +125°C)
  • Sink Current Capacity from 100µA to 100mA
  • Low Dynamic Impedance: 0.1Ω (typ.)
  • Wide Operating Temperature Range: -40°C to +125°C
  • Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
  • Halogen and Antimony Free. “Green” Device (Note 3)
  • For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/104/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative. https://www.diodes.com/quality/product-definitions/


  • Chargers
  • Voltage adapters
  • Switching power supplies
  • Graphic cards
  • Precision voltage references

Product Specifications

Product Parameters

Type Shunt regulator
Compliance (Only Automotive supports PPAP) Standard
AEC Qualified No
ReferenceVoltage (V) 2.5, 2.495 V
Tolerance (%) 0.5, 1 %
Maximum Input Voltage (V) 40 V
Sink Current (mA) 100 mA
Minimum Cathode Current for Regulation Typ (µA) 50 µA
Typical Temperature Coefficient (ppm/°C) 27 ppm/°C
Maximum Slope Resistance (Ω) 0.3 Ω
Operating Ambient Temperature Range (°C) -40 to 125 °C

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