TL431IZ Replacement: KA431AZBU, TL1431CLPE3

Original Part

TL431IZ

STMicroelectronics

Shunt Voltage Reference IC Adjustable 2.495V 36 VV ±2.21% 100 mA TO-92-3

Alternative Part

KA431AZBU

onsemi

Shunt Voltage Reference IC Adjustable 2.495V 36 VV ±1% 100 mA TO-92-3

TL1431CLPE3

Texas Instruments

Shunt Voltage Reference IC Adjustable 2.5V 36 VV ±0.4% 100 mA TO-92-3

1. KA431AZBU Substitution Conclusion From an electrical performance and package perspective, the KA431AZBU can serve as a direct replacement for the TL431IZ. The key parameters (output voltage range, cathode current, maximum output current) and the package (TO-92-3) are identical, ensuring fundamental circuit compatibility. The differences lie in the tolerance and temperature coefficient: the KA431AZBU offers a superior tolerance of ±1% (compared to the original's ±2.21%) and provides typical temperature drift data (50ppm/°C). This results in a more stable and precise reference voltage across varying operating temperatures, representing a direct performance upgrade. For the vast majority of applications, this substitution is both feasible and beneficial.

2. TL1431CLPE3 Substitution Conclusion The TL1431CLPE3 can functionally replace the TL431IZ in basic operation and package, but one key parameter difference requires special attention. Its package (TO-92-3) and primary electrical specifications (e.g., output voltage range, current capability) are compatible with the original part. The core differences are the initial tolerance and the nominal reference voltage (Voltage - Output (Min/Fixed)): the TL1431CLPE3 features a high-precision ±0.4% tolerance, but its nominal voltage is 2.5V (versus 2.495V for the original). This minor 0.005V (5mV) deviation will cause a systematic, proportional slight shift (approximately +0.2%) in all circuit thresholds or output voltages set based on this reference after substitution. In applications with stringent precision requirements (such as high-accuracy ADC references or precision voltage regulators), this discrepancy must be validated or fine-tuned at the design level. However, for general-purpose applications like switch-mode power supply feedback or error amplification, this substitution is typically viable and can significantly improve voltage accuracy.

Analysis ID: 9C1E-06BE000

Based on part parameters and for reference only. Not to be used for procurement or production.