Microchip Technology 93LC66AX-E/SN

Overview

93LC66AX-E/SN from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with 512 × 8-bit organization, Microwire-compatible 3-wire interface (CS/CLK/DI/DO), and automotive-grade temperature range (–40°C to +125°C). It features self-timed erase/write cycles, automatic ERAL before WRAL, power-on/off data protection, and 1,000,000 endurance cycles - used in engine control units, ABS modules, and automotive sensor calibration storage.

For engineers reviewing the 93LC66AX-E/SN datasheet, 93LC66AX-E/SN pinout, 93LC66AX-E/SN application, or 93LC66AX-E/SN equivalent, key selection criteria include V_CC range (2.5–5.5 V), automotive temp rating, 8-bit x512 organization (no ORG pin), SOIC-8 package (SN), and Ready/Busy status via DO pin during programming.

Technical Context

This device implements a synchronous serial Microwire protocol with start-bit detection, opcode-driven instruction set (READ/WRITE/ERASE/ERAL/WRAL/EWEN/EWDS), and hardware-level data protection via V_CC brown-out detection (1.5 V threshold). It operates without external timing components and supports sequential read mode when CS remains high.

Internal architecture includes an address counter, mode decode logic, output buffer, and memory array with auto-erase-before-write. The DO pin serves dual function: serial data output during READ and Ready/Busy status indicator during erase/write - requiring CS re-assertion for polling after T_CSSL ≥ 250 ns.

Key Specifications

Pinout & Package

8-pin SOIC package (SN suffix), Pb-free Matte Tin finish, 150 mil body width. Pin 1 marked by laser dot; pin 1 ID corner matches standard JEDEC SOIC orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66AX-E/SN, the 93LC66BT-E/SN offers higher data density per address but demands firmware revision, while AT25DF041A-SHN-T provides larger capacity at the cost of deterministic write timing and hardware-based data protection - making 93LC66AX-E/SN optimal for safety-critical automotive parameter storage.

Availability

93LC66AX-E/SN is available at Aetrix Electronics and suitable for engine control units, anti-lock braking systems, and transmission control modules requiring stable component supply across extended automotive production lifecycles.

Supply support for 93LC66AX-E/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 microcontroller, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 93LC66A series belongs to Microchip's legacy Microwire-compatible EEPROM product line, designed specifically for automotive and industrial applications demanding high reliability, wide temperature operation, and hardware-enforced data protection.

FAQ

What is the maximum clock frequency supported by the 93LC66AX-E/SN?

The 93LC66AX-E/SN supports up to 3 MHz clock frequency when V_CC ≥ 4.5 V, 2 MHz at 2.5 V ≤ V_CC < 4.5 V, and 1 MHz at 1.8 V ≤ V_CC < 2.5 V. These limits ensure reliable setup/hold timing across automotive temperature ranges. The 93LC66AX-E/SN does not require external clock dividers and tolerates clock pauses during instruction framing.

Does the 93LC66AX-E/SN have an ORG pin, and how does it affect memory organization?

No, the 93LC66AX-E/SN does not have an ORG pin - it is an 'A'-suffix device with fixed 512 × 8-bit organization. Pin 6 is NC (no internal connection), eliminating external configuration components. This differs from 'C'-suffix variants where ORG selects x8/x16 mode. The 93LC66AX-E/SN simplifies design by removing ORG routing and pull-up/pull-down requirements.

How does the 93LC66AX-E/SN protect against inadvertent writes during power transitions?

The 93LC66AX-E/SN incorporates hardware-level V_CC monitoring that disables all erase/write functions when supply voltage drops below 1.5 V. Additionally, it powers up in EWDS (Erase/Write Disable) mode, requiring an explicit EWEN command before any programming. These dual protections prevent corruption during ignition cycling, battery disconnect, or load-dump transients - critical for automotive use of the 93LC66AX-E/SN.

What is the purpose of the DO pin during write operations on the 93LC66AX-E/SN?

During write operations, the DO pin on the 93LC66AX-E/SN serves as a Ready/Busy status indicator: logic low indicates active erase/write in progress, and logic high signals completion. To poll this status, CS must be brought high for ≥250 ns after T_CSSL, then sampled on subsequent CLK edges. This eliminates need for fixed delay loops and enables efficient MCU resource utilization in the 93LC66AX-E/SN.

Can the 93LC66AX-E/SN be used in place of the 93LC66AT-I/SN in an existing design?

Yes, the 93LC66AX-E/SN is pin-compatible and functionally identical to the 93LC66AT-I/SN except for temperature grade: 'E' supports –40°C to +125°C versus 'I' (–40°C to +85°C). Electrical specs (V_CC, timing, endurance) are identical. No PCB or firmware changes are required - the 93LC66AX-E/SN extends operational range for under-hood applications while maintaining full backward compatibility.