1. AD822ARMZ-REEL Substitution Conclusion Direct substitution is not recommended. While both are dual rail-to-rail output operational amplifiers, their key parameters differ significantly. The AD822ARMZ has a minimum operating voltage of 5V, whereas the original part can operate down to 2.7V. This discrepancy may prevent proper startup in low-voltage systems. Furthermore, its supply current is 1.24mA, which is over 20 times higher than the original part's 54μA (dual). This would severely increase system power consumption, contradicting the original design's ultra-low-power intent. Although the AD822ARMZ offers superior performance in bandwidth (1.9 MHz vs. 35 kHz) and slew rate (3V/µs vs. 0.01V/µs), and features an extremely low input bias current (2 pA), these advantages do not compensate for the fundamental incompatibilities in supply voltage and power consumption. Additionally, its 8-MSOP package is not a direct drop-in replacement for the original 8-SOIC package in terms of PCB layout.