Microchip Technology 93C66C-E/MS

Overview

93C66C-E/MS from Microchip Technology Inc. is a 4 Kbit Microwire-compatible serial EEPROM with configurable 8-/16-bit word organization via the ORG pin, 4.5–5.5 V supply range, -40°C to +125°C automotive temperature grade, and MSOP-8 package. It supports self-timed erase/write cycles, automatic ERAL/WRAL, and Ready/Busy status signaling - used for nonvolatile parameter storage in automotive control modules.

For engineers reviewing the 93C66C-E/MS datasheet, 93C66C-E/MS pinout, 93C66C-E/MS application, or 93C66C-E/MS equivalent, key selection criteria include its automotive-grade reliability, ORG-configurable data width, 2 ms write cycle time, 1 million endurance cycles, and compatibility with legacy Microwire host controllers requiring minimal firmware changes.

Technical Context

The 93C66C-E/MS implements a synchronous 3-wire serial interface (CS, CLK, DI/DO) with start-bit detection and opcode-based command execution. Its memory array is organized as 512 × 8-bit or 256 × 16-bit depending on ORG pin logic level, and all programming operations (ERASE, WRITE, ERAL, WRAL) are self-timed with status reported via DO pin polling.

Write initiation differs from earlier 93AA/93LC variants: for 93C66C-E/MS, the rising edge of CLK on the final data bit triggers the auto-erase-and-write cycle, not the falling edge of CS. VCC must be ≥4.5 V for ERAL and WRAL operations, and power-on data protection activates below 3.8 V.

Key Specifications

Pinout & Package

Package: 8-lead MSOP (Micro Small Outline Package), 3.0 mm × 3.0 mm body, 0.65 mm pitch, exposed pad optional (VSS or floating).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66C-E/MS and AT25DF041A-MAU-T, the 93C66C-E/MS uniquely delivers automotive-grade 125°C operation within the Microwire ecosystem, enabling drop-in replacement in existing 5 V ECU designs without changing interface logic or thermal management.

Availability

93C66C-E/MS is available at Aetrix Electronics and suitable for automotive control units, ADAS camera modules, electric power steering systems, and body control modules requiring stable component supply across extended product lifecycles.

Supply support for 93C66C-E/MS 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 93C66C-E/MS belongs to Microchip's legacy 93XX serial EEPROM family, designed specifically for cost-sensitive, low-pin-count nonvolatile storage in automotive and industrial control applications where Microwire compatibility and robustness under voltage transients are critical.

FAQ

What is the function of the ORG pin on the 93C66C-E/MS?

The ORG pin on the 93C66C-E/MS selects memory organization: logic high configures 256 × 16-bit mode; logic low configures 512 × 8-bit mode. It must be statically tied to VCC or VSS before operation - dynamic switching is not supported. This pin is absent on A/B variants but is essential for 93C66C-E/MS flexibility in mixed-data-width systems.

Does the 93C66C-E/MS require an external pull-up resistor on the DO pin?

No, the 93C66C-E/MS does not require an external pull-up on DO. The DO pin actively drives high/low during read or Ready/Busy status reporting and enters High-Z when inactive. However, if DI and DO are shorted (shared bus), a series resistor (typically 1–10 kΩ) is required to prevent bus conflict during the dummy zero of read operations.

How does the 93C66C-E/MS handle power loss during a write cycle?

The 93C66C-E/MS incorporates power-on/off data protection: its POR circuit inhibits all operations when VCC falls below 3.8 V, preventing partial writes or corruption. Combined with self-timed erase/write and automatic ERAL before WRAL, this ensures atomicity - either the full write completes or no change occurs, preserving data integrity during brownout conditions.

Can the 93C66C-E/MS be used in place of the 93C66B-E/MS?

Yes, the 93C66C-E/MS can replace the 93C66B-E/MS with minor hardware modification: the 93C66B-E/MS lacks the ORG pin (fixed 16-bit), while the 93C66C-E/MS adds it (configurable). To retain 16-bit behavior, tie ORG to VCC. No firmware changes are needed - instruction set, timing, and pinout (except NC→ORG) are identical.

What is the maximum clock frequency supported by the 93C66C-E/MS at 5.0 V?

At VCC = 5.0 V (within 4.5–5.5 V range), the 93C66C-E/MS supports a maximum clock frequency of 3 MHz. This is confirmed in Table 1-2 (A1), where FCLK max = 3 MHz applies for 4.5 V ≤ VCC < 5.5 V. Exceeding this violates tCKH/tCKL timing and risks command misinterpretation.