1. TL431CZ Substitution Conclusion The TL431CZ can generally substitute for the LM431AIZ, but with potential degradations in key accuracy and temperature characteristics that require evaluation. The differences are as follows: First, the initial tolerance is relaxed from ±2% to ±2.21%, resulting in slightly greater dispersion in the output voltage reference. This may introduce larger errors in circuits with stringent accuracy requirements, such as high‑precision power supplies or measurement references. Second, the TL431CZ datasheet does not specify a guaranteed temperature coefficient (the typical 50ppm/°C value may not be assured), whereas the original part provides a typical specification. Over a wide temperature range, the output voltage drift of the TL431CZ could be greater and less predictable. The core functions—adjustable shunt reference, 2.495V/2.5V reference voltage, 36V maximum rating, 100mA output current—and the TO‑92‑3 package are fully compatible. Therefore, in applications where high accuracy and tight temperature performance are not critical, such as ordinary switching‑power‑supply feedback loops, the TL431CZ can serve as a direct replacement. However, system‑level performance should be verified to ensure it still meets specifications.