LM431AIZ

Voltage Reference Overview

The LM431AIZ is a three-terminal adjustable precision shunt regulator manufactured by Fairchild Semiconductor. It provides a stable reference voltage that can be programmed to any value between approximately 2.5 volts and 36 volts using two external resistors. The device features a typical dynamic output impedance of 0.2 ohms and supports a sink current capability ranging from 1.0 mA to 100 mA. It operates over an extended temperature range from -40°C to +85°C with a typical full-range temperature coefficient of 50 ppm/°C. Packaged in TO-226AA-3, it serves as a direct replacement for Zener diodes in various circuit applications.

Voltage Reference Feature Summary

• Programmable output voltage adjustable between VREF and 36 volts via external resistors
• Low dynamic output impedance ensuring stable regulation performance
• Temperature compensated operation across the full industrial rated temperature range

Voltage Reference Applications

• Precision voltage references in power supply circuits
• Replacement for Zener diodes requiring sharp turn-on characteristics
• Adjustable shunt regulators in feedback control loops

Voltage Reference Procurement Notes

Verify the manufacturer marking on the component body to confirm Fairchild Semiconductor origin, as multiple vendors produce compatible LM431 variants. Ensure the package matches the specified TO-226AA-3 form factor for proper board integration. Cross-reference the suffix 'AIZ' with official datasheets to confirm specific tolerance and temperature grade requirements before finalizing procurement orders.

Voltage Reference Selection Notes

Select this component when a low-cost, high-precision adjustable reference is required to replace fixed Zener diodes. The wide programmable voltage range allows flexibility in setting reference points without changing the component type. Consider the thermal stability and low noise characteristics for applications demanding accurate regulation over varying environmental conditions.

Voltage Reference Part Context

The LM431 series represents a widely adopted family of three-terminal adjustable shunt regulators. Originally developed by National Semiconductor and later acquired by Fairchild Semiconductor, these devices are standard components in analog circuit design. The LM431AIZ specifically denotes the version packaged in TO-226AA-3, maintaining compatibility with legacy designs while offering improved thermal stability compared to basic Zener implementations.

Voltage Reference Replacement Considerations

Direct pin-compatible substitutes include the TL431 and LM431BIZ. Verify that alternative manufacturers maintain identical electrical specifications, particularly the 0.2 ohm dynamic output impedance and 50 ppm/°C temperature coefficient, to ensure circuit performance remains unchanged.