Microchip Technology 93LC66C-E/SN

Overview

93LC66C-E/SN from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with Microwire-compatible 3-wire interface, ORG-pin-selectable 8-/16-bit word organization, and automotive-grade temperature range (–40°C to +125°C). It supports self-timed erase/write cycles, automatic ERAL before WRAL, and Ready/Busy status signaling via DO pin - used in engine control units for calibration storage.

For engineers reviewing the 93LC66C-E/SN datasheet, 93LC66C-E/SN pinout, 93LC66C-E/SN application, or 93LC66C-E/SN equivalent, key selection criteria include VCC range (2.5–5.5 V), endurance (1 million cycles), data retention (>200 years), and compatibility with legacy Microwire controllers requiring CS/CLK/DI/DO timing compliance.

Technical Context

The 93LC66C-E/SN implements a synchronous serial interface with start-bit detection, opcode-driven instruction set (READ, WRITE, ERASE, ERAL, WRAL, EWEN/EWDS), and dual-organization memory array configurable via external logic on the ORG pin. Its internal state machine handles auto-erase-before-write and full-array operations without host intervention.

Timing is governed by voltage-dependent clock frequency limits (up to 3 MHz at VCC ≥ 4.5 V), with critical parameters including TCSL (250 ns min), TPD (≤400 ns), and TWC (6 ms write cycle). Power-on protection disables programming below 2.5 V, and EWEN/EWDS commands enforce explicit write-enable discipline.

Key Specifications

Pinout & Package

93LC66C-E/SN is packaged in 8-lead SOIC (SN) with standard pinout: Pin 1 = CS, Pin 2 = CLK, Pin 3 = DI, Pin 4 = DO, Pin 5 = VSS, Pin 6 = ORG, Pin 7 = NC, Pin 8 = VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66B-E/SN, the 93LC66C-E/SN offers runtime organization switching - critical for mixed-data-width systems - while AT25DF041A-SHN-T trades EEPROM simplicity for density and speed at the cost of safety-critical write control.

Availability

93LC66C-E/SN is available at Aetrix Electronics and suitable for automotive ECU design, industrial PLC configuration, and medical device data logging requiring stable component supply across extended product lifecycles.

Supply support for 93LC66C-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 93LC66C-E/SN belongs to Microchip's legacy Microwire EEPROM product line, designed specifically for cost-sensitive, low-power, and automotive-qualified nonvolatile memory applications requiring simple 3-wire interface and robust data integrity.

FAQ

What is the maximum clock frequency supported by the 93LC66C-E/SN?

The 93LC66C-E/SN supports up to 3 MHz clock frequency when VCC is 4.5 V to 5.5 V, 2 MHz at 2.5 V to 4.5 V, and 1 MHz at 1.8 V to 2.5 V. These limits are defined in Table 1-2 AC Characteristics and directly impact throughput in high-speed logging applications. The 93LC66C-E/SN must operate within these bounds to ensure reliable opcode decoding and data transfer integrity.

How does the ORG pin affect memory organization in the 93LC66C-E/SN?

In the 93LC66C-E/SN, tying ORG to VCC selects 256 × 16-bit organization, while tying it to VSS selects 512 × 8-bit organization. This pin must be statically biased - floating causes undefined behavior. Unlike A/B variants, the 93LC66C-E/SN requires this external logic level to configure word width at power-on, enabling one hardware design to serve multiple host architectures.

Does the 93LC66C-E/SN require an external pull-up resistor on the DO pin?

No, the 93LC66C-E/SN does not require an external pull-up on DO. The output buffer actively drives high/low during READ or Ready/Busy status reporting, and enters High-Z when CS is low or during non-read states. However, if DI and DO are wire-OR'd (common bus), a series resistor is recommended to prevent bus conflict during the dummy-zero phase of READ.

What is the purpose of the EWEN and EWDS commands in the 93LC66C-E/SN?

The EWEN (Erase/Write Enable) and EWDS (Erase/Write Disable) commands in the 93LC66C-E/SN provide hardware-enforced write protection. The 93LC66C-E/SN powers up in EWDS mode, blocking all erase/write operations until EWEN is issued. After any write, issuing EWDS restores protection - preventing accidental corruption during noise events or software faults. This is mandatory for functional safety compliance.

Can the 93LC66C-E/SN be used in place of the 93LC66A-E/SN?

No, the 93LC66C-E/SN cannot directly replace the 93LC66A-E/SN because the latter has no ORG pin and is fixed at 512 × 8-bit organization. While both share the same SOIC-8 package and voltage range, substituting them requires verifying host firmware supports dynamic ORG control and adjusting address/data handling for optional 16-bit mode - making it a design-level change, not a drop-in swap.