1. LM431AIZ Substitution Conclusion When functional pinout and basic parameters (2.5V reference, 36V withstand voltage, 100mA capability) are compatible, the LM431AIZ can serve as a low-cost alternative or a substitution where initial accuracy is not critical. However, it is not a drop-in equivalent due to significant performance degradation. Key differences include its initial accuracy tolerance of ±2%, which is substantially wider than the original part's ±0.4%. This leads to greater output voltage dispersion in volume production, potentially impacting circuit absolute accuracy and consistency. Its temperature coefficient is specified as 50ppm/°C (typical), which is nominally better than the original's 100ppm/°C. However, "typical" is not a guaranteed maximum; actual drift performance must be evaluated based on specific lots and operating conditions. This substitution is suitable for systems insensitive to reference voltage accuracy or where subsequent calibration can compensate for the variance.