Microchip Technology 93AA66T-I/SN

Overview

93AA66T-I/SN from Microchip Technology Inc. is a 4K-bit (512 × 8 or 256 × 16) low-voltage serial EEPROM with Microwire interface, ORG-pin configurable memory organization, and industrial temperature support (–40°C to +85°C). It operates down to 1.8V, delivers 70 µA typical active read current at 1.8V, and ensures 1,000,000 erase/write cycles with >200-year data retention. It is used in embedded system parameter storage, sensor calibration data logging, and power-meter firmware configuration.

For engineers reviewing the 93AA66T-I/SN datasheet, 93AA66T-I/SN pinout, 93AA66T-I/SN application, or 93AA66T-I/SN equivalent, key selection criteria include its 1.8V–5.5V supply range, SOIC-8 (SN) package with rotated pinout, self-timed erase/write, power-on/off data protection, and compatibility with legacy Microwire controllers in space-constrained industrial designs.

Technical Context

The 93AA66T-I/SN implements a synchronous 3-wire Microwire interface with CS, CLK, and bidirectional DI/DO lines, supporting both x8 and x16 memory organizations selected via the ORG pin. Its internal logic includes an address counter, output buffer, and mode decode logic enabling sequential read and status polling via DO during erase/write operations.

It features automatic ERAL before WRAL, self-timed programming cycles (4 ms per word for WRITE/ERASE, 8 ms for ERAL, 16 ms for WRAL), and power-supply monitoring that inhibits programming below 1.4V. The device enters EWDS mode at power-up and requires explicit EWEN to enable erase/write functions.

Key Specifications

Pinout & Package

8-pin SOIC package (JEDEC MS-012, 150 mil body), marked "/SN" per Microchip's product identification system. The 93AA66T-I/SN uses the rotated pinout variant specific to SN packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93AA66C-I/SN, the 93AA66T-I/SN offers identical functionality but lacks the newer process enhancements and formal new-design recommendation; compared with AT25040B-MAU-1.8, it retains Microwire compatibility and ORG-selectable organization at the cost of interface flexibility and modern SPI ecosystem support.

Availability

93AA66T-I/SN is available at Aetrix Electronics and suitable for smart energy meters, industrial PLC I/O modules, and medical infusion pumps requiring stable component supply across extended product lifecycles.

Supply support for 93AA66T-I/SN 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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and memory products for embedded control applications.

The 93AA66T-I/SN belongs to Microchip's legacy 93AAxx Microwire EEPROM family, designed specifically for low-voltage, low-power nonvolatile storage in resource-constrained industrial and automotive subsystems where simple 3-wire communication and hardware-configurable memory mapping are critical.

FAQ

What is the memory organization of the 93AA66T-I/SN and how is it configured?

The 93AA66T-I/SN provides 4 Kbit of memory in either 512 × 8-bit or 256 × 16-bit organization, selected by the ORG pin: tied to V_CC for x16 mode, to V_SS for x8 mode. This configuration is latched at power-up and determines instruction addressing and data width. The 93AA66T-I/SN datasheet confirms this behavior in Section 2.0 and Tables 1-6/1-7, which list distinct instruction sets for each mode.

Does the 93AA66T-I/SN support true SPI communication?

No, the 93AA66T-I/SN implements the Microwire protocol - a subset of SPI with single bidirectional data line (DI/DO), no dedicated MISO/MOSI, and no SS/CS polarity inversion. It is not SPI-compatible without bit-banging emulation. The 93AA66T-I/SN requires strict adherence to Microwire timing (e.g., TCSL ≥250 ns) and instruction opcodes defined in Tables 1-6 and 1-7 of its datasheet.

What is the purpose of the NU pin on the 93AA66T-I/SN?

The NU (Not Utilized) pin on the 93AA66T-I/SN has no internal connection and serves only as a mechanical placeholder in the SOIC-8 (SN) package. Per Microchip DS20067K-page 11, it must remain unconnected or be tied to V_SS/V_CC for board-level noise immunity - it does not affect device operation or timing.

How does the 93AA66T-I/SN handle power transitions to protect stored data?

The 93AA66T-I/SN incorporates hardware power-on/off data protection: programming is inhibited until V_CC exceeds 1.4V at startup, and disabled when V_CC drops below 1.4V during shutdown. This prevents partial writes during brown-out. Additionally, the 93AA66T-I/SN powers up in EWDS mode, requiring explicit EWEN before any erase/write - further safeguarding against unintended modifications.

Is the 93AA66T-I/SN pin-compatible with the 93AA66C-I/SN?

Yes, the 93AA66T-I/SN and 93AA66C-I/SN share identical pinout, package (SOIC-8 SN), electrical specifications, and functional behavior. Microchip explicitly positions the 93AA66C-I/SN as the recommended replacement per DS20067K-page 1 ("Not recommended for new designs – Please use 93AA66C…"), confirming full mechanical and logical compatibility for drop-in replacement in existing designs.