Microchip Technology 93C66AT-I/MS

Overview

93C66AT-I/MS from Microchip Technology Inc. is a 4 Kbit (512 × 8-bit) low-voltage serial EEPROM with Microwire-compatible 3-wire interface, 4.5–5.5 V supply range, industrial temperature rating (–40°C to +85°C), and MSOP-8 package. It provides nonvolatile storage for configuration data in microcontroller-based systems requiring reliable, low-power memory with automatic erase-before-write and hardware data protection.

For engineers reviewing the 93C66AT-I/MS datasheet, 93C66AT-I/MS pinout, 93C66AT-I/MS application, or 93C66AT-I/MS equivalent, key selection criteria include its fixed 8-bit organization (no ORG pin), 2 ms write cycle time, 1 million endurance cycles, 200-year data retention, and compatibility with legacy Microwire controllers in space-constrained industrial designs.

Technical Context

The 93C66AT-I/MS implements a synchronous serial interface using CS, CLK, and DI/DO signals with start-bit detection and opcode-driven command execution. Its internal architecture includes an address decoder, mode decode logic, and output buffer supporting sequential read, ERASE, WRITE, ERAL, WRAL, EWEN, and EWDS instructions.

It operates exclusively in x8 mode (no ORG pin - tied internally as NC), requires VCC ≥ 4.5 V for ERAL/WRAL execution, and uses rising-edge clocking for data input/output. Ready/Busy status is reported via DO pin polling during self-timed erase/write cycles, with TCSL ≥ 250 ns between instructions.

Key Specifications

Pinout & Package

8-pin MSOP (150-mil) package with exposed pad (optional VSS connection), Pb-free Matte Tin finish. Pin 1 marked by laser dot; pin 1 ID corner defined per JEDEC MO-187.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66AT-I/MS, the 93C66AT-I/MS offers higher noise immunity in 5 V systems but sacrifices 3.3 V compatibility; versus AT25040B-MAU-5A, it retains legacy Microwire support and deterministic 2 ms writes but lacks SPI flexibility and smaller UDFN options.

Availability

93C66AT-I/MS is available at Aetrix Electronics and suitable for industrial sensor calibration, embedded system configuration, and legacy PLC modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for 93C66AT-I/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 components, and memory solutions, headquartered in Chandler, Arizona, serving industrial, automotive, and consumer markets since 1989.

The 93Cxx series was designed specifically for cost-sensitive, space-constrained applications needing simple, robust serial EEPROM with Microwire compatibility and strong data integrity - targeting legacy and upgrade paths in industrial control and instrumentation.

FAQ

What is the function of the ORG pin on the 93C66AT-I/MS?

The ORG pin is not functional on the 93C66AT-I/MS - it is internally unconnected (NC) as confirmed in the Device Selection Table and Pin Function Table. This part belongs to the 'A' variant family (93C66A), which has fixed 8-bit organization and no ORG pin capability. The pin must be left floating or tied to VSS/VCC per layout guidelines, but it does not affect memory configuration. All 93C66AT-I/MS devices operate exclusively in x8 mode.

Does the 93C66AT-I/MS support 3.3 V operation?

No, the 93C66AT-I/MS does not support 3.3 V operation. Its absolute VCC range is strictly 4.5 V to 5.5 V, as specified in the Device Selection Table and Electrical Characteristics section. Attempting to power the 93C66AT-I/MS below 4.5 V will disable programming functions (ERAL, WRAL require ≥4.5 V) and may cause unreliable read behavior or data corruption. For 3.3 V systems, consider the 93LC66AT-I/MS instead.

How is data protection implemented in the 93C66AT-I/MS?

Data protection in the 93C66AT-I/MS is implemented through three layers: (1) Power-on/off detection with 3.8 V threshold (VPOR) disabling all operations below that level; (2) Erase/Write Disable (EWDS) mode at power-up, requiring explicit EWEN before any programming; and (3) mandatory post-write EWDS execution recommended in the datasheet to prevent accidental overwrites. These features ensure data integrity during brownouts, resets, and firmware errors.

What is the maximum clock frequency supported by the 93C66AT-I/MS?

The 93C66AT-I/MS supports a maximum clock frequency (FCLK) of 3 MHz when VCC is 4.5–5.5 V, as specified in Table 1-2 (AC Characteristics). This applies to all instructions (READ, WRITE, ERASE, etc.). Timing parameters such as TCKH (200 ns min), TCKL (100 ns min), and TDIS (50 ns min) are guaranteed across the full industrial temperature range at this speed, enabling reliable communication with standard 5 V microcontrollers.

Can the 93C66AT-I/MS be used in automotive applications?

No, the 93C66AT-I/MS is rated for Industrial temperature range only (–40°C to +85°C) and is not qualified for automotive use. Automotive-grade variants exist in the same family (e.g., 93C66BT-E/MS with 'E' suffix), which are tested to –40°C to +125°C and meet AEC-Q100 stress requirements. Using the 93C66AT-I/MS in automotive environments risks parametric failure outside its validated operating envelope and voids qualification compliance.