Microchip Technology 93AA66-I/SN

Overview

93AA66-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 1.8V–5.5V single-supply operation. It delivers 70 µA typical active read current at 1.8V, 2 µA standby current, and supports industrial temperature range (−40°C to +85°C) in an 8-lead SOIC (SN) package. It is used for nonvolatile parameter storage in embedded control systems requiring robust power-on/off data protection.

For engineers reviewing the 93AA66-I/SN datasheet, 93AA66-I/SN pinout, 93AA66-I/SN application, or 93AA66-I/SN equivalent, key selection criteria include its 1.8V minimum operating voltage, self-timed erase/write cycles (4 ms/word), 1 million endurance cycles, 200+ year data retention, and compatibility with legacy Microwire-based microcontroller peripherals.

Technical Context

The 93AA66-I/SN implements a synchronous 3-wire Microwire serial interface (CS, CLK, DI, DO) with start-bit detection and opcode-driven command set. Its internal architecture includes address counter, output buffer, data register, mode decode logic, and clock generator - enabling sequential read, ERAL/WRAL bulk operations, and RDY/BSY status polling via DO pin.

Memory configuration is determined by the ORG pin: tied to V_CC selects 256 × 16-bit organization; tied to V_SS selects 512 × 8-bit organization. Programming requires explicit EWEN instruction before ERASE/WRITE, and automatic ERAL precedes WRAL. All erase/write cycles are self-timed and fully completed before device returns to ready state.

Key Specifications

Pinout & Package

8-lead SOIC (SN) package per JEDEC MS-012 standard, 150 mil body width, surface-mount compatible.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93AA66C-I/SN, the 93AA66-I/SN lacks updated ESD hardening and is marked "Not recommended for new designs"; compared with AT25040B-MAU-1.8, it offers native Microwire compatibility and proven integration with legacy 8-bit controllers but at lower maximum clock rate.

Availability

93AA66-I/SN is available at Aetrix Electronics and suitable for industrial sensor calibration, automotive ECU configuration, and medical device settings requiring stable component supply across extended product lifecycles.

Supply support for 93AA66-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 leading provider of microcontrollers, analog devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 93AA66-I/SN belongs to Microchip's legacy 93AA-series Microwire EEPROM product line, designed specifically for cost-sensitive, low-power embedded systems requiring simple, reliable nonvolatile storage with minimal pin count and firmware overhead.

FAQ

What is the memory organization flexibility of the 93AA66-I/SN?

The 93AA66-I/SN supports two memory configurations selected by the ORG pin: 512 × 8-bit when ORG is tied to V_SS, or 256 × 16-bit when ORG is tied to V_CC. This allows designers to optimize data access granularity-byte-level for configuration registers or word-level for compact firmware metadata-without changing the physical part. The 93AA66-I/SN does not support floating ORG above 1 MHz clock rates.

How does the 93AA66-I/SN handle power transitions to prevent data corruption?

The 93AA66-I/SN incorporates hardware power-on/off data protection that inhibits all erase/write operations until V_CC rises above 1.4V, and re-enables protection when V_CC falls below that threshold. Combined with mandatory EWEN instruction before programming and automatic ERAL before WRAL, this ensures the 93AA66-I/SN cannot execute partial writes during brown-out or startup, preserving memory integrity across uncontrolled power events.

What is the timing behavior of the 93AA66-I/SN during a WRITE instruction?

After loading address and data bits, the 93AA66-I/SN initiates a self-timed WRITE cycle upon the falling edge of CS (≥250 ns low). During execution, the DO pin outputs RDY/BSY status: low indicates ongoing programming, high signals completion. The typical cycle time is 4 ms per word, and no further CLK activity is required. The 93AA66-I/SN guarantees this timing across its full 1.8V–5.5V supply and −40°C to +85°C temperature range.

Can the 93AA66-I/SN be used with a shared DI/DO bus line?

The 93AA66-I/SN permits DI and DO sharing under specific conditions: the host must avoid driving A0 high during the dummy-zero phase of READ, as this may cause bus conflict and undefined DO voltage. A pull-up resistor on DO is required when polling RDY/BSY status after erase/write. While feasible, dedicated DI/DO lines are preferred for robust timing and noise immunity in production systems using the 93AA66-I/SN.

Is the 93AA66-I/SN still recommended for new designs?

No - Microchip explicitly marks the 93AA66-I/SN as "Not recommended for new designs" in DS20067K, advising migration to the enhanced 93AA66C-I/SN variant. The 93AA66C-I/SN offers identical pinout, functionality, and electrical specs but with improved ESD robustness (6 kV HBM) and updated process technology. Existing 93AA66-I/SN designs remain supported, but new projects should specify 93AA66C-I/SN for long-term supply assurance.