1. 24AA64-E/ST Substitution Conclusion From the perspective of core electrical parameters and package, the 24AA64-E/ST can serve as a direct replacement. Both devices are identical in memory capacity (64Kbit), interface (I2C at 400kHz), operating voltage range (1.7V to 5.5V), write cycle time (5ms), and package type (8-TSSOP). The primary difference is that the 24AA64-E/ST explicitly specifies an access time (900ns), a parameter not listed for the original part. However, this discrepancy is typically inconsequential in practical applications, as the timing of the I2C interface is primarily governed by the clock frequency, and the access time is significantly faster than the bus data rate. Potential risks to note include possible unmarked variations in manufacturer-specific I2C protocol details (such as address bit definitions or write protection control methods) or the size of the internal page write buffer. It is recommended to verify read/write operation compatibility in the actual circuit before finalizing the substitution.