Microchip Technology 93LC66C-I/MS

Overview

93LC66C-I/MS 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 grade (–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 embedded control systems.

For engineers reviewing the 93LC66C-I/MS datasheet, 93LC66C-I/MS pinout, 93LC66C-I/MS application, or 93LC66C-I/MS equivalent, key selection considerations include ORG-pin-configurable memory width, self-timed erase/write with ERAL/WRAL support, Ready/Busy status signaling on DO, and MSOP-8 packaging for space-constrained PCB layouts.

Technical Context

The 93LC66C-I/MS implements a synchronous Microwire-compatible serial interface with CS, CLK, DI, and DO signals, where instruction execution begins on a Start condition (CS high + DI high at 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-based data protection including power-on/off voltage detection (V_POR = 1.5 V), automatic Erase All (ERAL) before Write All (WRAL), and EWEN/EWDS lockout commands. Programming cycles are fully self-timed - T_WC = 6 ms for erase/write, T_EC = 6 ms for ERAL, and T_WL = 15 ms for WRAL - with Ready/Busy status readable via DO pin polling.

Key Specifications

Pinout & Package

Package: 8-lead MSOP (Micro Small Outline Package), 3.0 mm × 3.0 mm body, 0.65 mm pitch, Pb-free Matte Tin finish, exposed pad optional (not electrically connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66B-I/MS, the 93LC66C-I/MS adds ORG-driven flexibility at identical package and voltage specs; versus AT25040B-MAHL-T, it offers protocol compatibility with existing Microwire firmware but lower maximum clock rate.

Availability

93LC66C-I/MS is available at Aetrix Electronics and suitable for industrial sensor calibration, consumer appliance configuration, and medical device parameter logging requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for 93LC66C-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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 93LC66C belongs to Microchip's legacy 93XX serial EEPROM product line, designed specifically for low-power, pin-efficient nonvolatile storage in resource-constrained embedded systems across industrial, automotive, and consumer markets.

FAQ

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

The ORG pin on the 93LC66C-I/MS selects memory organization: tied to VSS (GND), it configures the device as 512 × 8-bit; tied to VCC, it configures as 256 × 16-bit. This pin must be externally biased to a valid logic level - floating is not permitted. The 93LC66C-I/MS requires this pin for mode selection, unlike the fixed-organization 93LC66A-I/MS or 93LC66B-I/MS variants.

Does the 93LC66C-I/MS support SPI communication?

No, the 93LC66C-I/MS does not support SPI. It implements a Microwire-compatible 3-wire serial interface (CS, CLK, DI/DO) with specific timing and instruction encoding defined in Microchip DS21795E. While functionally similar to SPI in using clocked serial data, it lacks MOSI/MISO separation and uses distinct opcodes and timing requirements - direct SPI host integration requires protocol translation or firmware adaptation.

What is the minimum V_CC required for reliable operation of the 93LC66C-I/MS?

The 93LC66C-I/MS requires V_CC ≥ 2.5 V for full specification compliance across its Industrial temperature range (–40°C to +85°C). Its internal power-on reset (POR) circuit activates at approximately 1.5 V, inhibiting all operations below that threshold to prevent corrupted writes. Operation below 2.5 V is not characterized and may result in undefined behavior or incomplete programming cycles.

How is Ready/Busy status monitored on the 93LC66C-I/MS?

Ready/Busy status on the 93LC66C-I/MS is signaled on the DO pin: logic low indicates an erase or write operation is in progress; logic high indicates completion and readiness for the next command. To read status, CS must first be brought low for ≥250 ns (T_CSL), then raised high - DO will reflect status within T_SV (200–500 ns depending on V_CC). Issuing a Start bit followed by CS low clears the status flag.

Is the 93LC66C-I/MS pin-compatible with other 93XX66 devices in MSOP-8 package?

Yes, the 93LC66C-I/MS shares identical MSOP-8 pinout and footprint with 93LC66A-I/MS and 93LC66B-I/MS, including CS, CLK, DI, DO, VSS, NC, ORG (functionally NC on A/B), and VCC assignments. However, functional compatibility depends on ORG usage: 93LC66A lacks ORG (fixed 8-bit), 93LC66B lacks ORG (fixed 16-bit), while 93LC66C requires ORG connection - PCBs must route ORG to support full 93LC66C-I/MS functionality.