Microchip Technology 93C66AT-E/SN

Overview

93C66AT-E/SN from Microchip Technology Inc. is a 4 Kbit serial EEPROM IC with 512 × 8-bit organization, operating in the 4.5–5.5 V supply range and rated for automotive temperature (−40°C to +125°C). It uses Microwire-compatible 3-wire serial interface (CS/CLK/DI/DO), features self-timed erase/write cycles, automatic ERAL/WRAL support, and power-on/off data protection. It is used in automotive body control modules for storing calibration data and configuration settings.

For engineers reviewing the 93C66AT-E/SN datasheet, 93C66AT-E/SN pinout, 93C66AT-E/SN application, or 93C66AT-E/SN equivalent, key selection criteria include its automotive-grade temperature rating, 8-bit fixed word size (no ORG pin), 2 ms write cycle time, 1 million endurance cycles, and SOIC-8 (SN) package compatibility with legacy board layouts.

Technical Context

The 93C66AT-E/SN implements a synchronous Microwire-compatible serial interface with dedicated CS, CLK, DI, and DO pins - no shared bidirectional data line. Its internal logic requires a Start bit (CS high + DI high on first CLK rising edge) before accepting opcode, address, and data. All programming operations (ERASE, WRITE, ERAL, WRAL) are self-timed and initiated by either the falling edge of CS (for 93AA/93LC) or the rising edge of CLK on the final data bit (for 93C series).

It features hardware-level data protection: VCC voltage detect (3.8 V threshold) inhibits all operations below that level; power-on defaults to EWDS (Erase/Write Disable) mode; and EWEN must precede any erase/write. Ready/Busy status is reported via DO pin when CS is reasserted after ≥250 ns low time, enabling polling-based timing control without external delays.

Key Specifications

Pinout & Package

Package: 8-lead SOIC (SN), Pb-free Matte Tin finish, standard industrial footprint compatible with automated SMT assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93C66B-E/SN and 93LC66A-E/SN, the 93C66AT-E/SN offers strict 5 V operation ideal for legacy automotive 5 V MCUs, fixed 8-bit simplicity for drop-in firmware reuse, and highest noise immunity in electrically noisy engine compartments.

Availability

93C66AT-E/SN is available at Aetrix Electronics and suitable for automotive body control, instrument cluster, engine management, and infotainment systems requiring stable component supply across extended product lifecycles.

Supply support for 93C66AT-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 microcontrollers, analog devices, and memory solutions, headquartered in Chandler, Arizona, serving automotive, industrial, and consumer markets globally.

The 93C66A/B/C family was designed specifically for automotive and industrial applications demanding high-reliability, low-pin-count serial EEPROM with robust power-supply supervision and extended temperature operation.

FAQ

What is the memory organization of the 93C66AT-E/SN?

The 93C66AT-E/SN has a fixed 512 × 8-bit organization. Unlike C-variant parts, it does not feature an ORG pin - its word size is permanently configured for 8-bit operation. This simplifies hardware design by eliminating external pull-up/pull-down resistors and removes ambiguity in firmware data handling. The 93C66AT-E/SN delivers deterministic 8-bit access without runtime configuration overhead.

Does the 93C66AT-E/SN require an external pull-up resistor on the DO pin?

No, the 93C66AT-E/SN does not require an external pull-up on DO. Its DO pin is actively driven high or low during read or Ready/Busy reporting, and enters high-impedance (High-Z) state when CS is low or during non-read operations. External pull-ups may interfere with valid logic levels and are unnecessary per Microchip's recommended interface design in DS21795E.

How is data protection implemented in the 93C66AT-E/SN?

Data protection in the 93C66AT-E/SN is enforced through three mechanisms: (1) VCC voltage detection at 3.8 V - all write/erase operations are inhibited below this threshold; (2) Power-on default to EWDS (Erase/Write Disable) mode - EWEN must be issued before any programming; (3) Automatic hardware reset of programming state upon power cycle. These ensure no unintended writes occur during power transitions.

What is the maximum clock frequency supported by the 93C66AT-E/SN?

The 93C66AT-E/SN supports a maximum clock frequency of 3 MHz when VCC is between 4.5 V and 5.5 V. This is specified in Table 1-2 (A1) of DS21795E. At lower voltages, the max clock rate decreases - but since the 93C66AT-E/SN is rated only for 4.5–5.5 V operation, 3 MHz is its guaranteed maximum interface speed for full timing compliance.

Can the 93C66AT-E/SN be used in place of the 93C66A-E/SN?

Yes, the 93C66AT-E/SN is functionally and pin-compatible with the 93C66A-E/SN. The "T" suffix denotes tape-and-reel packaging per Microchip's standard marking convention (see DS21795E page 14), and does not indicate electrical or functional differences. Both share identical electrical specs, timing, pinout, and automotive temperature rating - making them direct replacements in production and design.