Microchip Technology 93C66C-E/P

Overview

93C66C-E/P from Microchip Technology Inc. is a 4 Kbit serial EEPROM with Microwire-compatible 3-wire interface, ORG pin for dynamic 8-/16-bit word size selection, and industrial-temperature operation (–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 in embedded system configuration storage and calibration data retention.

For engineers reviewing the 93C66C-E/P datasheet, 93C66C-E/P pinout, 93C66C-E/P application, or 93C66C-E/P equivalent, key selection considerations include V_CC range (4.5–5.5 V), ORG-configurable memory organization, Ready/Busy status signaling via DO, and compatibility with legacy Microwire controllers in space-constrained industrial designs.

Technical Context

The 93C66C-E/P implements a synchronous serial interface with CS, CLK, and DI/DO pins, requiring a Start bit detection sequence before instruction execution. Its ORG pin directly controls internal address/data width: logic high selects 256 × 16-bit mode; logic low selects 512 × 8-bit mode - no internal multiplexing or auto-detection.

Write operations are self-timed: for 93C-series devices, the rising edge of CLK on the final data bit initiates auto-erase-and-write; ERAL and WRAL require V_CC ≥ 4.5 V and execute in 2 ms (TWC) and 15 ms (TWL), respectively. Power-down protection activates below 3.8 V (V_POR).

Key Specifications

Pinout & Package

93C66C-E/P is supplied in 8-lead PDIP (Plastic Dual In-line Package) with standard through-hole mounting. Pin 1 is CS, pin 2 is CLK, pin 3 is DI, pin 4 is DO, pin 5 is VSS, pin 6 is ORG, pin 7 is NC, and pin 8 is VCC. The NC pin has no internal connection and must be left unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66C-E/P and 93AA66C-E/P, the 93C66C-E/P offers highest noise immunity and fastest write timing (2 ms) but sacrifices voltage flexibility - making it optimal for robust 5 V industrial systems where supply stability is guaranteed.

Availability

93C66C-E/P is available at Aetrix Electronics and suitable for industrial sensor calibration storage, legacy controller configuration, and embedded power supply trim applications requiring stable component supply across long product lifecycles.

Supply support for 93C66C-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 microcontrollers, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, serving industrial, automotive, and consumer markets since 1989.

The 93C66C-E/P belongs to Microchip's legacy 93XX serial EEPROM family, designed specifically for cost-sensitive, reliability-critical industrial applications requiring simple 3-wire nonvolatile storage with hardware-level data protection.

FAQ

What is the function of the ORG pin on the 93C66C-E/P?

The ORG pin on the 93C66C-E/P selects memory organization: tied to VCC, it configures the device as 256 × 16-bit; tied to VSS, it configures as 512 × 8-bit. This pin must be externally biased - floating is undefined. The 93C66C-E/P requires this pin; it is not present on A/B variants.

Does the 93C66C-E/P support 3.3 V operation?

No, the 93C66C-E/P does not support 3.3 V operation. Its specified V_CC range is strictly 4.5 V to 5.5 V. Attempting to operate below 4.5 V may result in unreliable reads, failed writes, or activation of power-on reset protection below 3.8 V.

How does the Ready/Busy status work on the 93C66C-E/P DO pin?

During erase or write cycles, the DO pin outputs Ready/Busy status: logic low indicates ongoing operation; logic high indicates completion. Status is valid only after CS is brought high for ≥250 ns (TCSL); DO returns to High-Z on CS falling edge.

What is the maximum clock frequency supported by the 93C66C-E/P?

The 93C66C-E/P supports up to 3 MHz clock frequency when V_CC is 4.5–5.5 V. At lower voltages (not applicable here), timing de-rates: 2 MHz at 2.5–4.5 V, 1 MHz at 1.8–2.5 V - but the 93C66C-E/P is not rated below 4.5 V.

Is the 93C66C-E/P pin-compatible with other 93XX66C variants like 93LC66C-E/P?

Yes, the 93C66C-E/P shares identical 8-lead PDIP pinout and signal assignments with 93LC66C-E/P and 93AA66C-E/P. However, electrical differences - especially V_CC range, POR threshold, and AC timing - prevent direct substitution without system-level validation.