1. TL431IZ Substitution Conclusion The TL431IZ can functionally replace the TL431ACLP, but careful evaluation of two key differences is required. First, the reference voltage accuracy decreases from ±1% to ±2.21%, resulting in a wider output voltage tolerance. This may render it unsuitable for circuits demanding high precision, such as precision measurement systems or high-stability power supplies. Second, the minimum cathode operating current increases from 600 µA to 1 mA. The substitute requires higher current to properly start up and maintain stable regulation, which could impact low-power applications or cause failure in current-limited designs. If the target application can tolerate these variations—for instance, where precision is less critical and sufficient supply current is available—the substitution is viable. Otherwise, it is advisable to retain the original part or select an alternative with closer electrical specifications.