1. AD8422BRZ Substitution Conclusion The AD8422BRZ offers a viable drop-in replacement for the AD8221BRZ-RL, as it maintains pin compatibility and matches key input specifications such as input bias current, offset voltage, and supply voltage range. The differences between the two are as follows: the AD8422BRZ provides higher bandwidth (2.2 MHz vs. 825 kHz) and lower quiescent current (300 µA vs. 900 µA), resulting in reduced distortion at higher signal frequencies and significantly lower overall power consumption, making it better suited for battery-powered or energy-sensitive applications. However, its slew rate is lower (0.8 V/µs vs. 2 V/µs), which may lead to slightly slower response in large-signal step conditions or when driving full-scale output. Additionally, the AD8422BRZ supports rail-to-rail output, offering wider dynamic range at low supply voltages, whereas the output swing of the AD8221BRZ-RL may be more limited. If the application does not demand high-speed large-signal response but prioritizes bandwidth, power efficiency, or output range at low supply voltages, the AD8422BRZ represents a favorable performance upgrade. Conversely, if the system relies on high slew rate to handle fast transient signals, careful evaluation is recommended.