Microchip Technology 93LC66CX-E/SN

Overview

93LC66CX-E/SN from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with Microwire-compatible 3-wire interface, supporting 256 × 16-bit organization via ORG pin configuration, 2.5–5.5 V supply, and automotive-grade operation (−40°C to +125°C). It features self-timed erase/write cycles, automatic ERAL before WRAL, Ready/Busy status signaling, and 1 million erase/write endurance - used in automotive body control modules for storing calibration data and configuration settings.

For engineers reviewing the 93LC66CX-E/SN datasheet, 93LC66CX-E/SN pinout, 93LC66CX-E/SN application, or 93LC66CX-E/SN equivalent, key selection criteria include ORG-pin-configurable x16 memory mapping, automotive temperature compliance, Microwire protocol timing at up to 2 MHz (VCC ≥ 2.5 V), and integrated power-on/off data protection circuitry.

Technical Context

This device implements a synchronous serial Microwire interface with CS, CLK, DI, and DO signals, where instruction execution begins on detection of a Start bit (CS high and DI high on CLK rising edge). Memory organization is dynamically selected via the ORG pin: logic high enables 256 × 16-bit mode; logic low selects 512 × 8-bit mode - applicable only to 'C' variants like 93LC66CX-E/SN.

Internal operations include auto-erase-before-write, ERAL (Erase All) and WRAL (Write All) commands with dedicated opcodes, and EWEN/EWDS lockout controls. The DO pin serves dual function: serial data output during READ and Ready/Busy status indicator during programming - asserted low until completion of self-timed TWC = 6 ms erase/write cycle.

Key Specifications

Pinout & Package

93LC66CX-E/SN is packaged in an 8-lead SOIC (SN) with Pb-free Matte Tin finish. Pin 1 is CS; Pin 2 is CLK; Pin 3 is DI; Pin 4 is DO; Pin 5 is VSS; Pin 6 is ORG (functional - not NC); Pin 7 is NC; Pin 8 is VCC. ORG must be externally biased to VCC (x16) or VSS (x8); NC pin has no internal connection and must be left unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66B-E/SN, the 93LC66CX-E/SN offers field-selectable word size via ORG - enabling one PCB to support both 8-bit and 16-bit hosts. Versus AT25DF041A-SHN-T, it trades density and speed for Microwire simplicity, lower pin count, and guaranteed automotive qualification.

Availability

93LC66CX-E/SN is available at Aetrix Electronics and suitable for automotive electronics, industrial control systems, and medical device manufacturing requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for 93LC66CX-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, FPGA, and memory solutions, headquartered in Chandler, Arizona, serving automotive, industrial, consumer, and communications markets.

The 93LC66CX-E/SN belongs to Microchip's legacy 93XX series of Microwire-compatible EEPROMs, designed specifically for cost-sensitive, low-pin-count embedded systems requiring reliable nonvolatile storage in harsh environments.

FAQ

What is the function of the ORG pin on the 93LC66CX-E/SN?

The ORG pin on the 93LC66CX-E/SN determines memory organization: when tied to VCC, it configures the device as 256 × 16-bit; when tied to VSS, it configures as 512 × 8-bit. This pin is functional and mandatory for correct operation - unlike 'A' or 'B' variants where ORG is NC. The 93LC66CX-E/SN requires external biasing of ORG to select the desired word width before any instruction execution.

Does the 93LC66CX-E/SN support true 3-wire Microwire communication?

Yes, the 93LC66CX-E/SN implements a true 3-wire Microwire-compatible interface using CS, CLK, and DI/DO shared bidirectional line. However, its DO pin functions as both data output and Ready/Busy status indicator, requiring careful timing management during programming. Unlike strict 3-wire protocols, it uses separate DI and DO pins - making it a 4-signal (CS/CLK/DI/DO), 3-wire protocol-compatible device per Microchip's documentation.

What is the maximum clock frequency supported by the 93LC66CX-E/SN at 3.3 V?

At VCC = 3.3 V, the 93LC66CX-E/SN supports a maximum clock frequency of 2 MHz, as specified in Table 1-2 (A1: FCLK) for the 2.5 V ≤ VCC < 5.5 V range. This applies across the full automotive temperature range (−40°C to +125°C). Exceeding this limit may result in setup/hold violations and command rejection, especially under worst-case process/voltage/temperature corners.

How does the 93LC66CX-E/SN protect against accidental writes during power transitions?

The 93LC66CX-E/SN incorporates hardware-level power-on/off data protection: internal circuitry inhibits all write operations when VCC falls below 1.5 V (typical). Additionally, it powers up in EWDS (Erase/Write Disable) mode, requiring an explicit EWEN command before any ERASE or WRITE instruction executes. This dual-layer protection ensures data integrity during brown-out, cold start, or battery replacement events.

Is the 93LC66CX-E/SN pin-compatible with other 93XX66 variants in SOIC-8 (SN) package?

Yes, the 93LC66CX-E/SN shares identical SOIC-8 (SN) pinout and footprint with all 93XX66A/B/C variants in the same package, including 93LC66A-E/SN and 93LC66B-E/SN. Pin assignments (CS=1, CLK=2, DI=3, DO=4, VSS=5, ORG/NC=6, NC=7, VCC=8) are consistent. However, ORG functionality differs: it is active on 'C' variants like 93LC66CX-E/SN but NC on 'A'/'B' versions - requiring schematic review before substitution.