4 Kbit Microwire at 2 MHz — the interface that decides the fit
The 93AA66AT-I/SN: The Microwire interface is a three-wire serial protocol (SI, SO, SK) with a dedicated chip-select — it is not I²C or SPI, so the MCU or ASIC on the other end must have a Microwire port or bit-bang the timing. The 2 MHz clock rate is fast enough for most parameter-storage and calibration-ID reads; the 6 ms write cycle (word or page) sets the floor for in-application updates.
The supply range covers 1.8 V low-voltage cores up to 5 V legacy logic without a separate regulator. At 1.8 V the internal charge pump still generates the write voltage, so the part operates across the full range without a performance derating — the 2 MHz clock holds at any supply voltage within the window.
ROHS3 compliance — no exemption risk
The part is ROHS3 compliant, meaning no restricted substances above the threshold limits and no time-limited exemptions that could trigger a supply discontinuity.