Microchip Technology 93LC66B/P

Overview

93LC66B/P from Microchip Technology Inc. is a 4 Kbit, 256 × 16-bit organization, low-voltage serial EEPROM with Microwire-compatible 3-wire interface, operating from 2.5 V to 5.5 V, and rated for 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 Ready/Busy status signaling via DO pin - used in embedded system configuration storage and calibration data retention.

For engineers reviewing the 93LC66B/P datasheet, 93LC66B/P pinout, 93LC66B/P application, or 93LC66B/P equivalent, this page delivers verified electrical specs, package mapping, functional timing behavior, and real-world use context for reliable integration into microcontroller-based designs requiring nonvolatile memory with deterministic write latency and robust data retention.

Technical Context

The 93LC66B/P implements a fixed 256 × 16-bit memory array with no ORG pin - unlike 'C' variants - eliminating external configuration logic. Communication uses synchronous 3-wire protocol (CS, CLK, DI/DO) with start-bit detection, opcode-driven instruction set (READ, WRITE, ERASE, ERAL, WRAL), and status polling via DO during programming.

It supports auto-erase-before-write, automatic ERAL prior to WRAL, and EWEN/EWDS command-based write protection. Standby current is ≤5 µA at VCC = 2.5 V, and write cycle time is 6 ms across its full VCC range (2.5–5.5 V), with clock frequency up to 3 MHz at 4.5–5.5 V.

Key Specifications

Pinout & Package

93LC66B/P is supplied in 8-lead PDIP (Plastic Dual In-line Package), with lead pitch 0.1 inch (2.54 mm), body width 0.3 inch (7.62 mm), and RoHS-compliant matte tin finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66B/SN, the 93LC66B/P offers identical functionality in through-hole form for test fixtures and legacy systems; versus AT25040B-PU, it provides superior data integrity assurance via hardware-enforced auto-erase and simpler firmware integration despite lower clock rate.

Availability

93LC66B/P is available at Aetrix Electronics and suitable for industrial sensor calibration, embedded system configuration, and automotive body control module applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant through-hole packaging.

Supply support for 93LC66B/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 93LC66B/P belongs to Microchip's legacy 93XX series of Microwire-compatible serial EEPROMs, designed specifically for cost-sensitive, low-power embedded systems needing reliable nonvolatile storage with minimal pin count and deterministic write behavior.

FAQ

What is the memory organization of the 93LC66B/P?

The 93LC66B/P has a fixed 256 × 16-bit organization - meaning it stores 256 words of 16 bits each, totaling 4 Kbit. Unlike 'C' variants, it lacks an ORG pin and does not support runtime switching between 8-bit and 16-bit modes. This fixed configuration simplifies hardware design by removing the need for external logic to drive ORG, and ensures consistent data framing in firmware drivers for the 93LC66B/P.

Does the 93LC66B/P require an external pull-up resistor on the DO pin?

Yes - when sharing DI and DO on a single bidirectional bus line, a pull-up resistor (typically 4.7 kΩ to VCC) is required on the 93LC66B/P DO pin to prevent bus conflict during the dummy-zero phase of READ operations. Without it, undefined voltage levels may occur due to contention with address lines, risking data corruption. The 93LC66B/P datasheet explicitly recommends this resistor to ensure stable High-Z release and valid logic levels during status polling.

What is the maximum clock frequency supported by the 93LC66B/P?

The 93LC66B/P supports a maximum clock frequency of 3 MHz when VCC is between 4.5 V and 5.5 V. At 2.5 V ≤ VCC < 4.5 V, the limit drops to 2 MHz, and no specification is provided below 2.5 V. These limits are defined in Table 1-2 (AC Characteristics) of the DS21795E datasheet and directly impact achievable read/write throughput - for example, a 20-clock READ instruction completes in ~6.7 µs at 3 MHz, critical for real-time firmware response.

How does the 93LC66B/P handle power loss during a write operation?

The 93LC66B/P incorporates hardware-level power-loss protection: its internal power-on reset (POR) circuit disables all write functions when VCC falls below 1.5 V, preventing partial or corrupted writes. Additionally, the self-timed write architecture ensures that once initiated (via CS fall), the 6 ms erase-and-program cycle completes autonomously using on-chip charge pump energy - so brief dips above 1.5 V won't abort the operation. This makes the 93LC66B/P robust in battery-backed or unregulated supply environments.

Is the 93LC66B/P pin-compatible with other 93XX66 devices in PDIP package?

Yes - the 93LC66B/P shares identical 8-lead PDIP pinout and mechanical dimensions with all other 93XX66x/P variants (e.g., 93LC66A/P, 93AA66B/P), including matching CS, CLK, DI, DO, VSS, NC, VCC, and ORG/NC assignments. However, functional compatibility depends on organization (8-bit vs 16-bit) and VCC range: 93LC66B/P requires 2.5–5.5 V and operates only in 16-bit mode, so substituting a 93AA66A/P (1.8–5.5 V, 8-bit) would require firmware and voltage rail changes despite identical pin layout.