Microchip Technology 93AA66CT-I/MS

Overview

93AA66CT-I/MS from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with Microwire-compatible 3-wire interface, ORG pin for x8/x16 word-size selection, 1.8–5.5 V supply range, and industrial temperature rating (–40°C to +85°C). It delivers self-timed erase/write cycles, automatic ERAL/WRAL support, and 1,000,000 endurance cycles - used in microcontroller configuration storage and power-management parameter retention.

For engineers reviewing the 93AA66CT-I/MS datasheet, 93AA66CT-I/MS pinout, 93AA66CT-I/MS application, or 93AA66CT-I/MS equivalent, key selection criteria include voltage compatibility (1.8–5.5 V), MSOP-8 package footprint, ORG-configurable memory organization, Ready/Busy status signaling via DO, and compliance with Microwire timing requirements including TWC ≤ 6 ms and FCLK up to 3 MHz at 4.5–5.5 V.

Technical Context

The 93AA66CT-I/MS implements a synchronous serial interface using CS, CLK, and DI/DO lines with start-bit detection and opcode-driven command execution. Its internal architecture includes address decoder, mode decode logic, and output buffer, supporting both x8 (ORG = VSS) and x16 (ORG = VCC) configurations.

It features hardware-level data protection: power-on/off detection (VPOR = 1.5 V), EWEN/EWDS write-enable/disable control, and automatic ERAL before WRAL. Erase/write operations are self-timed with DO pin indicating Ready/Busy status after minimum TCSL = 250 ns.

Key Specifications

Pinout & Package

93AA66CT-I/MS is housed in an 8-lead MSOP (Micro Small Outline Package) with 0.15 mm lead pitch and exposed pad option (not connected per datasheet). Pin 1 marked by laser dot; pin 1 ID corner defined by package notch or beveled edge.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Compared with 93LC66CT-I/MS, the 93AA66CT-I/MS supports lower-voltage operation critical for energy-harvesting systems, while versus 93AA56CT-I/MS it provides double memory for complex calibration or multi-profile storage - all retaining pin-compatible MSOP-8 layout and Microwire protocol compatibility.

Availability

93AA66CT-I/MS is available at Aetrix Electronics and suitable for motor control firmware storage, smart sensor calibration data retention, and power supply sequencing profile management requiring stable component supply across extended production lifecycles.

Supply support for 93AA66CT-I/MS includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology Inc. is a leading provider of microcontrollers, analog devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 93XX series EEPROMs, including the 93AA66CT-I/MS, were designed for low-power, serially interfaced nonvolatile storage in space-constrained embedded systems - emphasizing voltage flexibility, data integrity, and ease of integration with resource-limited MCUs.

FAQ

What is the function of the ORG pin on the 93AA66CT-I/MS?

The ORG pin on the 93AA66CT-I/MS selects memory organization: logic high (VCC) configures 256 × 16-bit mode; logic low (VSS) configures 512 × 8-bit mode. It must be statically tied - not left floating - and is essential for matching the device's data width to the host controller's bus architecture. The 93AA66CT-I/MS requires this pin to be externally biased to define its operational word size.

Does the 93AA66CT-I/MS support true 3-wire SPI communication?

No, the 93AA66CT-I/MS implements Microwire-compatible 3-wire serial protocol - not SPI. It uses separate DI and DO lines (not bidirectional MOSI/MISO), requires start-bit detection, and follows opcode-based instruction framing (e.g., READ = 10b prefix). While pin-count matches SPI, timing, command structure, and protocol state machine differ; direct SPI hardware mapping is not supported without bit-banging or protocol translation.

What is the maximum clock frequency supported by the 93AA66CT-I/MS at 3.3 V operation?

At VCC = 3.3 V (within 2.5–5.5 V range), the 93AA66CT-I/MS supports a maximum clock frequency of 2 MHz, as specified in Table 1-2 (A1: FCLK). This is lower than the 3 MHz maximum allowed at 4.5–5.5 V. Designers must respect this derating to ensure reliable opcode/address/data capture and avoid timing violations during read/write sequences.

How does the 93AA66CT-I/MS handle power loss during a write cycle?

The 93AA66CT-I/MS incorporates hardware power-loss protection: if VCC drops below 1.5 V (VPOR threshold), all internal operations halt and write/erase functions are inhibited. No partial writes occur - the memory contents remain intact at their pre-cycle state. Recovery requires power restoration and explicit reissuance of EWEN followed by the intended command, ensuring atomicity of configuration updates.

Is the NC pin on the 93AA66CT-I/MS required to be grounded or left floating?

The NC (No Connection) pin on the 93AA66CT-I/MS - Pin 7 in the MSOP-8 package - has no internal connection and must be left floating. It is not bonded to die and carries no electrical function. Grounding or driving this pin may cause mechanical stress or unintended coupling; Microchip's datasheet explicitly lists it as "No internal connection" and shows no recommended termination.