Microchip Technology 93LC66C-E/P

Overview

93LC66C-E/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, and industrial/automotive temperature support (−40°C to +125°C). It features Microwire-compatible 3-wire serial interface, self-timed erase/write cycles, automatic ERAL before WRAL, and power-on/off data protection - used in embedded system configuration storage and calibration data retention.

For engineers reviewing the 93LC66C-E/P datasheet, 93LC66C-E/P pinout, 93LC66C-E/P application, or 93LC66C-E/P equivalent, key selection considerations include ORG-pin-configurable memory width, automotive-grade endurance (1M cycles), Ready/Busy status signaling on DO, and compatibility with legacy Microwire controllers requiring strict timing compliance at 2.5 V.

Technical Context

The 93LC66C-E/P implements a synchronous serial Microwire interface with start-bit detection, opcode-driven command set (READ, WRITE, ERASE, ERAL, WRAL, EWEN/EWDS), and dual-organization memory array (512 × 8 or 256 × 16) selected by external logic level on ORG. Its internal state machine handles auto-erase prior to write and supports sequential read without reissuing address.

Timing is strictly voltage-dependent: max clock frequency is 2 MHz at VCC = 2.5 V, rising to 3 MHz at VCC ≥ 4.5 V; TWC (program cycle time) is 6 ms for 93LC versions; ERAL and WRAL require VCC ≥ 4.5 V and execute fully self-timed with DO indicating Ready/Busy status after CS high pulse ≥ 250 ns.

Key Specifications

Pinout & Package

Package: 8-lead PDIP (E/P suffix denotes Automotive grade, Pb-free Matte Tin finish).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66B-E/P and 93LC66A-E/P, the 93LC66C-E/P provides hardware-selectable word width - enabling one PCB design to support both 8-bit and 16-bit host interfaces through simple ORG pin strapping, reducing inventory and qualification effort.

Availability

93LC66C-E/P is available at Aetrix Electronics and suitable for automotive ECU configuration, industrial sensor calibration, and medical device parameter storage requiring stable component supply across extended product lifecycles.

Supply support for 93LC66C-E/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 microcontroller, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 93LC66C belongs to Microchip's legacy Microwire-compatible serial EEPROM product line, designed specifically for robust, low-power nonvolatile storage in automotive, industrial, and medical systems where proven reliability and long-term supply stability are critical.

FAQ

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

The ORG pin on the 93LC66C-E/P selects memory organization: tied to VCC it configures the device as 256 × 16 (x16), and tied to VSS it configures as 512 × 8 (x8). This pin is absent on 93LC66A-E/P and 93LC66B-E/P variants. The 93LC66C-E/P requires external biasing - no internal pull-up/down - and must be held at a valid logic level during operation to ensure correct addressing and data width alignment.

Does the 93LC66C-E/P support true 3-wire SPI communication?

No, the 93LC66C-E/P implements Microwire protocol - a subset of SPI with single bidirectional data line (DI/DO), strict start-bit detection, and opcode-based command structure. It lacks SPI mode bits, CPOL/CPHA configuration, and full-duplex capability. While electrically compatible with many SPI masters via software bit-banging, it does not comply with standard SPI frame formatting or timing requirements defined in JEDEC or NXP specifications.

What is the minimum VCC required to execute ERAL or WRAL on the 93LC66C-E/P?

The 93LC66C-E/P requires VCC ≥ 4.5 V to execute ERAL (Erase All) or WRAL (Write All) commands. This is explicitly specified in the datasheet (DS21795E, pages 8 and 11). Attempting these operations below 4.5 V will result in undefined behavior or incomplete execution. Standard READ, WRITE, and ERASE functions remain operational down to 2.5 V.

How is Ready/Busy status monitored on the 93LC66C-E/P?

Ready/Busy status on the 93LC66C-E/P is monitored by polling the DO pin: DO = low indicates ongoing erase/write operation; DO = high indicates completion. To sample status, CS must first be brought low for ≥250 ns (TCSL), then brought high - after which DO reflects status within TSV (200–500 ns). Issuing a Start bit followed by CS low clears the status flag. DO returns to High-Z on CS falling edge.

Is the 93LC66C-E/P pin-compatible with the 93LC66C-I/P?

Yes, the 93LC66C-E/P and 93LC66C-I/P share identical pinout, package (8-lead PDIP), and electrical characteristics except for temperature rating: E grade is qualified for −40°C to +125°C (automotive), while I grade is −40°C to +85°C (industrial). Both use the same Pb-free Matte Tin finish and have identical AC/DC parametric limits within their respective temperature ranges.