Microchip Technology 93LC66C-I/P

Overview

93LC66C-I/P from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with configurable 8-/16-bit word organization via the ORG pin, 2.5–5.5 V supply range, industrial temperature rating (–40°C to +85°C), and Microwire-compatible 3-wire serial interface. It delivers 1 million erase/write cycles and >200 years data retention for nonvolatile storage in microcontroller-based systems.

For engineers reviewing the 93LC66C-I/P datasheet, 93LC66C-I/P pinout, 93LC66C-I/P application, or 93LC66C-I/P equivalent, key selection criteria include ORG-pin-configurable memory width, self-timed erase/write with ERAL/WRAL support, Ready/Busy status signaling on DO, and compatibility with legacy Microwire controllers in space-constrained embedded designs.

Technical Context

The 93LC66C-I/P implements a synchronous serial Microwire interface with CS, CLK, DI, and DO signals, where instruction execution begins on detection of a Start bit (CS high and DI high on CLK rising edge). Memory organization is dynamically selected: ORG = VSS enables 512 × 8-bit mode; ORG = VCC enables 256 × 16-bit mode.

It features hardware-level data protection including power-on/off voltage monitoring (V_POR = 1.5 V), automatic Erase All (ERAL) before Write All (WRAL), and Erase/Write Enable/Disable (EWEN/EWDS) command sequencing. All programming operations are self-timed, with T_WC = 6 ms for erase/write and T_EC = 6 ms for ERAL at V_CC ≥ 4.5 V.

Key Specifications

Pinout & Package

8-lead PDIP package (P suffix), with 0.3-inch body width and through-hole mounting. Pin 1 marked by notch or dot; pin 1 ID confirmed per Microchip DS21795E-page 18.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66B-I/P and 93LC66A-I/P, the 93LC66C-I/P provides unique configurability: a single footprint supports either 8-bit or 16-bit hosts via ORG pin strapping, reducing BOM variants and enabling late-stage hardware differentiation without PCB revision.

Availability

93LC66C-I/P is available at Aetrix Electronics and suitable for industrial sensor calibration, consumer remote control memory, and automotive body control module applications requiring stable component supply, long-term obsolescence management, and RoHS-compliant packaging.

Supply support for 93LC66C-I/P 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, with global design and manufacturing operations.

The 93LC66C-I/P belongs to Microchip's legacy 93XX serial EEPROM family, designed specifically for cost-sensitive, low-power embedded systems requiring reliable nonvolatile storage with minimal external components and broad voltage/temperature operation.

FAQ

What is the function of the ORG pin on the 93LC66C-I/P?

The ORG pin on the 93LC66C-I/P selects memory organization: tied to V_CC, it configures the device as 256 × 16-bit; tied to V_SS, it configures as 512 × 8-bit. This pin must be externally biased-floating is not permitted. The 93LC66C-I/P is the only variant in the 93LC66 family with this configurable feature; A and B versions lack ORG and are fixed-width.

Does the 93LC66C-I/P require external pull-up resistors on its I/O pins?

The 93LC66C-I/P does not require external pull-ups on CS, CLK, or DI for basic operation, as internal weak pull-downs assist start-bit detection. However, DO is open-drain and requires an external pull-up (typically 4.7 kΩ to V_CC) to ensure valid logic-high output during read or Ready/Busy status reporting. Pull-ups are mandatory for reliable DO functionality.

How does the 93LC66C-I/P handle power-loss during a write cycle?

The 93LC66C-I/P incorporates hardware power-loss protection: if V_CC drops below 1.5 V during erase/write, the internal circuitry halts the operation and preserves existing memory contents. No data corruption occurs. Additionally, the device powers up in EWDS (Erase/Write Disable) mode, preventing unintended writes until an explicit EWEN command is issued.

Can the 93LC66C-I/P be used with modern SPI controllers?

Yes-the 93LC66C-I/P is Microwire-compatible, and most SPI controllers can emulate Microwire timing with CPOL = 0, CPHA = 0, and MSB-first transmission. Critical differences include the Start bit requirement (CS high + DI high on first CLK rising edge) and lack of standard SPI chip-select polarity inversion. Firmware must implement Start-bit detection and adhere to Microwire-specific instruction lengths (e.g., 12 or 20 clocks for READ).

What is the maximum clock frequency supported by the 93LC66C-I/P at 3.3 V?

At V_CC = 3.3 V (within 2.5–5.5 V range), the 93LC66C-I/P supports a maximum clock frequency of 2 MHz, as specified in Table 1-2 (A1 parameter). This is confirmed by the "2.5V ≤ V_CC < 5.5V" row in the AC Characteristics table. Exceeding 2 MHz may violate t_CKH/t_CKL timing margins and cause command misreads.