Microchip Technology 93AA66B-I/MS

Overview

93AA66B-I/MS from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with dedicated 16-bit organization, 1.8–5.5 V supply range, and industrial temperature rating (–40°C to +85°C). It uses Microwire-compatible 3-wire serial interface (CS, CLK, DI, DO), supports self-timed erase/write cycles, and delivers 1 million endurance cycles with >200 years data retention. Used in embedded system configuration storage where compact nonvolatile memory with deterministic timing is required.

For engineers reviewing the 93AA66B-I/MS datasheet, 93AA66B-I/MS pinout, 93AA66B-I/MS application, or 93AA66B-I/MS equivalent, key selection criteria include 16-bit word access mode, MSOP-8 package compatibility, industrial-grade reliability, and support for ERAL/WRAL bulk operations without external address decoding.

Technical Context

The 93AA66B-I/MS implements a fixed 256 × 16-bit memory array with no ORG pin-unlike 'C' variants-so word size is hardwired to 16 bits. All instructions (READ, WRITE, ERASE, ERAL, WRAL, EWEN/EWDS) are synchronized to the rising edge of CLK and require CS high during command execution.

It features hardware-based power-on/off data protection, Ready/Busy status polling via DO pin, and automatic erase-before-write. Write cycle time is 6 ms (TWC) at VCC ≥ 4.5 V, with full compatibility across PDIP, SOIC, TSSOP, MSOP, DFN, and SOT-23 packages.

Key Specifications

Pinout & Package

8-lead MSOP (MS) package with exposed pad (optional VSS connection); pin 1 marked by laser dot. Pin functions match standard Microwire topology and are electrically identical across all 8-pin packages (SOIC, TSSOP, MSOP, DFN).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66B-I/MS, the 93AA66B-I/MS adds 1.8 V operation for ultra-low-power systems; compared with 93AA66A-I/MS, it delivers native 16-bit access that reduces command overhead and improves write atomicity for word-aligned parameters.

Availability

93AA66B-I/MS is available at Aetrix Electronics and suitable for motor control configuration, medical device calibration, industrial PLC I/O mapping, and smart energy meter firmware parameter storage requiring stable component supply across extended temperature ranges and multi-decade product lifecycles.

Supply support for 93AA66B-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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 93AA66B-I/MS belongs to Microchip's legacy 93XX serial EEPROM family, designed specifically for cost-sensitive, space-constrained embedded systems requiring reliable nonvolatile storage with minimal external components and broad voltage compatibility.

FAQ

What is the memory organization of the 93AA66B-I/MS?

The 93AA66B-I/MS has a fixed 256 × 16-bit organization - meaning it stores 256 words of 16 bits each, totaling 4 Kbit. Unlike 'C' variants, it does not have an ORG pin; its 16-bit word structure is hardwired, eliminating configuration overhead and ensuring deterministic addressing for 16-bit microcontrollers. This is confirmed in the Device Selection Table and Functional Description section of DS21795E.

Does the 93AA66B-I/MS support 1.8 V operation?

Yes, the 93AA66B-I/MS supports a VCC range of 1.8 V to 5.5 V, making it compatible with modern low-voltage microcontrollers and battery-powered systems. Its power-on reset (POR) threshold is 1.5 V, ensuring robust data protection during brown-out conditions. This specification is explicitly listed in the Device Selection Table and Electrical Characteristics section of DS21795E.

What package type is used for the 93AA66B-I/MS?

The 93AA66B-I/MS uses an 8-lead MSOP (Mini Small Outline Package) with dimensions 3.0 mm × 4.9 mm and 0.65 mm lead pitch. The package marking includes "3A66BT" and temperature grade "I", and pin 1 is identified by a laser mark. Package details are documented in the Packaging Information section and Figure 4-1 of DS21795E.

How does write protection work on the 93AA66B-I/MS?

The 93AA66B-I/MS implements hardware-based write protection via Erase/Write Disable (EWDS) and Enable (EWEN) instructions. It powers up in EWDS mode, blocking all erase/write operations until an explicit EWEN command is issued. After programming, executing EWDS re-locks the memory. This dual-instruction scheme prevents accidental writes during noise events or power transitions, as described in Section 2.6 of DS21795E.

What is the maximum clock frequency supported by the 93AA66B-I/MS?

The 93AA66B-I/MS supports a maximum clock frequency of 3 MHz at VCC ≥ 4.5 V, 2 MHz at 2.5 V ≤ VCC < 4.5 V, and 1 MHz at 1.8 V ≤ VCC < 2.5 V. These AC timing limits are specified in Table 1-2 (A1) of DS21795E and apply across the full industrial temperature range. Clock timing is strictly referenced to rising edges, and CLK may be paused mid-command without affecting state.