Microchip Technology 93LC66AT-I/ST

Overview

93LC66AT-I/ST from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with 512 × 8-bit organization, Microwire-compatible 3-wire interface (CS, CLK, DI/DO), and industrial temperature range (–40°C to +85°C). It features self-timed erase/write cycles, automatic ERAL before WRAL, power-on/off data protection, and 1,000,000 endurance cycles - used for configuration storage in embedded microcontroller systems.

For engineers reviewing the 93LC66AT-I/ST datasheet, 93LC66AT-I/ST pinout, 93LC66AT-I/ST application, or 93LC66AT-I/ST equivalent, key selection criteria include V_CC range (2.5–5.5 V), absence of ORG pin (fixed x8 mode), TSSOP-8 package compatibility, Ready/Busy status via DO pin, and support for sequential read and WRAL/ERAL commands.

Technical Context

This device implements a synchronous serial Microwire protocol with start-bit detection, opcode-driven instruction set (READ, WRITE, ERASE, EWEN/EWDS, ERAL, WRAL), and internal auto-erase-before-write logic. All operations are initiated by CS high-to-low transition after valid clocked instruction sequence.

It uses CMOS EEPROM cell technology with on-chip voltage pump for write/erase, supports single-byte and full-array programming, and provides hardware-level data protection via V_CC brown-out detection (1.5 V threshold) and write-disable default at power-up.

Key Specifications

Pinout & Package

8-pin TSSOP package (ST suffix), 3.0 mm × 4.4 mm body, 0.65 mm pitch. Pin 1 marked by laser dot; exposed pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66B-I/ST, the 93LC66AT-I/ST offers simpler x8 addressing and eliminates ORG pin routing; versus AT25040B-SSHL-T, it retains Microwire compatibility and hardware-ready signaling but trades SPI ubiquity for protocol-specific optimization.

Availability

93LC66AT-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration, consumer appliance configuration, and medical device settings storage requiring stable component supply across multi-year production cycles.

Supply support for 93LC66AT-I/ST 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.

The 93LC66A/B/C family delivers low-power, Microwire-compatible serial EEPROMs optimized for cost-sensitive, pin-constrained embedded systems requiring robust nonvolatile storage with minimal external components.

FAQ

What is the memory organization of the 93LC66AT-I/ST?

The 93LC66AT-I/ST is a 512 × 8-bit (4 Kbit) device with fixed x8 organization. It belongs to the 'A' variant group, meaning the ORG pin is not functional and is internally disconnected - no external configuration is needed to select word size. This simplifies design versus C-variant parts that require ORG pin biasing.

Does the 93LC66AT-I/ST support sequential read operations?

Yes, the 93LC66AT-I/ST supports sequential read: when CS remains high after a READ instruction, the internal address counter automatically increments, allowing continuous output of consecutive memory locations on the DO pin with each CLK rising edge - reducing host MCU overhead for bulk data retrieval.

What is the maximum clock frequency supported by the 93LC66AT-I/ST?

The 93LC66AT-I/ST supports up to 3 MHz clock frequency when V_CC is 4.5 V to 5.5 V. At 2.5 V ≤ V_CC < 4.5 V, maximum clock frequency is 2 MHz. These limits are defined in Table 1-2 (AC Characteristics) of the DS21795E datasheet and ensure reliable setup/hold timing across voltage and temperature ranges.

How does the 93LC66AT-I/ST handle power-loss during write operations?

The 93LC66AT-I/ST incorporates hardware-level power-loss protection: its V_CC detector disables all write/erase functions below ~1.5 V, preventing partial writes. Additionally, the device powers up in EWDS (Erase/Write Disable) mode, requiring an explicit EWEN command before any programming - ensuring unintended writes cannot occur during power ramp.

Is the 93LC66AT-I/ST RoHS compliant and Pb-free?

Yes, the 93LC66AT-I/ST is Pb-free and RoHS compliant, as confirmed in the "Features" section of DS21795E. It uses Matte Tin (Sn) finish on all package leads, meeting JEDEC J-STD-609 Category 1 requirements, and is suitable for environmentally regulated industrial and medical applications.