1. BU7271G-TR Substitution Conclusion Based on a comparison of key performance parameters, direct substitution of the ADA4051-1ARJZ-R2 with the BU7271G-TR is not recommended. While the two parts are fully compatible in package (SOT-23-5) and supply voltage range (1.8V to 5.5V), and the BU7271G-TR holds a slight edge in quiescent current and input bias current, a fundamental difference exists at their core: the ADA4051-1 is a "zero-drift" amplifier, whereas the BU7271G-TR is a "standard" amplifier. This directly results in an orders-of-magnitude disparity in input offset voltage (2µV vs. 1mV). In applications requiring high precision and stability for DC or low-frequency signal amplification—such as sensor bridge circuits or precision measurement—using the BU7271G-TR would introduce up to 500 times greater initial error and significant temperature drift error, severely degrading system accuracy. Furthermore, the ADA4051-1 offers minor advantages in bandwidth, slew rate, and output drive capability. Substitution may only be considered in scenarios with extremely low requirements for DC accuracy and long-term stability, where only package and supply compatibility are of concern. Otherwise, the original part or other zero-drift amplifiers should be prioritized.