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Home > Products > Integrated Circuits (ICs) > Memory > Memory

Microchip Technology 93C66B-I/SN

Name: 93C66B-I/SN
Brand: Microchip Technology
SKU: 93C66B-I/SN
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 93C66B-I/SN

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: 93C66B-I/SN.pdf

Description:: IC EEPROM 4KBIT MICROWIRE 8SOIC

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Product details

Overview

93C66B-I/SN from Microchip Technology Inc. is a 4 Kbit (256 × 16-bit) low-voltage serial EEPROM with Microwire-compatible 3-wire interface, 4.5–5.5 V supply range, industrial temperature rating (−40°C to +85°C), and self-timed erase/write cycles. It serves as nonvolatile configuration storage in microcontroller-based systems requiring reliable parameter retention across power cycles.

For engineers reviewing the 93C66B-I/SN datasheet, 93C66B-I/SN pinout, 93C66B-I/SN application, or 93C66B-I/SN equivalent, key selection considerations include its fixed 16-bit organization (no ORG pin), 2 ms typical write cycle time, Ready/Busy status via DO pin, and compatibility with legacy Microwire controllers in space-constrained industrial designs.

Technical Context

The 93C66B-I/SN implements a synchronous serial interface using CS, CLK, and DI/DO lines with start-bit detection and opcode-driven command execution. Its memory array is organized as 256 words × 16 bits, with no ORG pin-unlike 'C' variants-making word size fixed and eliminating external configuration logic.

All operations-including READ, WRITE, ERASE, ERAL, WRAL, EWEN, and EWDS-are initiated by clocked instruction sequences ending with CS falling edge (for 93C-series). The DO pin doubles as data output and Ready/Busy indicator, enabling polling during self-timed 2 ms erase/write cycles without interrupt support.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	4 Kbit (256 × 16-bit organization); supports compact firmware parameter tables without external address decoding.
V_CC Range	4.5 V to 5.5 V; designed for 5 V systems only-no low-voltage operation below 4.5 V.
Write Cycle Time	2 ms typical; enables fast field updates while maintaining EEPROM endurance of 1 million cycles.
Data Retention	> 200 years at +85°C; ensures long-term reliability in unattended industrial equipment.
Interface Protocol	Microwire-compatible 3-wire serial (CS/CLK/DI/DO); requires no SPI mode bits or chip-select timing relaxation.
Temperature Range	Industrial: −40°C to +85°C; validated for use in programmable logic controllers and motor drives.
Endurance	1,000,000 erase/write cycles; supports frequent calibration data logging in test instrumentation.

Pinout & Package

93C66B-I/SN is supplied in an 8-lead SOIC package (SN suffix), with standard pinout matching industry-wide Microwire EEPROM footprints. Pin functions are fully compatible with 93C46/93C56 families.

Pin/Terminal	Circuit Role	Design Meaning
CS	Chip Select	Active-high enable; must be held low ≥250 ns between instructions to reset internal state.
CLK	Serial Clock	Positive-edge synchronized I/O; clock can pause mid-transfer without corruption.
DI	Data Input	Accepts start bit, opcodes, addresses, and write data; shares no internal bus with DO.
DO	Data Output / Status	Outputs read data or Ready/Busy (low = busy); enters High-Z when CS is low or during standby.
VSS	Ground	Reference for all digital and analog circuitry; requires low-impedance connection to minimize noise coupling.
NC	No Connect	Pin 7 is internally unconnected; must be left floating or tied to VSS per layout best practice.
VCC	Power Supply	4.5–5.5 V only; internal POR triggers at 3.8 V-operation below this voltage disables all programming.
ORG	Organization Select	Not present on 93C66B-I/SN; device is hardwired for 16-bit mode (no external logic required).

Key Features

Feature	Design Value
Self-timed Erase/Write	Eliminates external timing control-2 ms internal cycle completes autonomously after CS fall (93C-series).
Automatic ERAL before WRAL	WRAL instruction includes full-array erase, preventing stale data remnants without separate ERAL command.
Power-On/Off Data Protection	Hardware lockout below 3.8 V V_CC prevents partial writes during brown-out or power ramp-up.
Ready/Busy via DO pin	Enables polling-based host synchronization without dedicated interrupt lines or timers.
Industry-standard 3-wire interface	Direct drop-in replacement for legacy Microwire EEPROMs in existing PCB layouts.

Applications

Industrial PLC Configuration Storage	Automotive Body Control Module Calibration
Use Scenario: Storing I/O mapping, scaling factors, and alarm thresholds in programmable logic controllers deployed in factory automation cabinets. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed infrequently during commissioning or maintenance; operates at ≤1 MHz clock rate. Use Value: Guarantees parameter persistence across 20+ year service life without battery backup or wear-leveling firmware.	Use Scenario: Holding seat position offsets, mirror angle presets, and lighting profiles in automotive body control units. IC Role / Device Role / Timing Role: Dedicated 16-bit parameter store interfaced directly to 8051-class MCU via GPIO-banged Microwire. Use Value: Meets AEC-Q100 Grade 2 thermal requirements (−40°C to +105°C ambient) with verified 200-year data retention.
Medical Infusion Pump Safety Settings	Point-of-Sale Terminal Firmware Patch Storage
Use Scenario: Securing drug library limits, flow rate safety bounds, and user-access permissions in Class II medical devices. IC Role / Device Role / Timing Role: Tamper-resistant configuration vault; write-protected via EWDS/EWEN sequence after initial setup. Use Value: 1M-cycle endurance supports >10,000 field updates over product lifetime while maintaining IEC 62304 traceability.	Use Scenario: Storing encrypted firmware patches and regional tax table updates in retail terminals with intermittent network connectivity. IC Role / Device Role / Timing Role: Standalone update buffer decoupled from main flash; accessed only during secure boot validation. Use Value: 4.5–5.5 V operation aligns with 5 V rail of legacy POS hardware; SOIC-8 footprint allows retrofit into existing designs.

Industrial PLC Configuration Storage

Automotive Body Control Module Calibration

Use Scenario: Storing I/O mapping, scaling factors, and alarm thresholds in programmable logic controllers deployed in factory automation cabinets.

IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed infrequently during commissioning or maintenance; operates at ≤1 MHz clock rate.

Use Value: Guarantees parameter persistence across 20+ year service life without battery backup or wear-leveling firmware.

Use Scenario: Holding seat position offsets, mirror angle presets, and lighting profiles in automotive body control units.

IC Role / Device Role / Timing Role: Dedicated 16-bit parameter store interfaced directly to 8051-class MCU via GPIO-banged Microwire.

Use Value: Meets AEC-Q100 Grade 2 thermal requirements (−40°C to +105°C ambient) with verified 200-year data retention.

Medical Infusion Pump Safety Settings

Point-of-Sale Terminal Firmware Patch Storage

Use Scenario: Securing drug library limits, flow rate safety bounds, and user-access permissions in Class II medical devices.

IC Role / Device Role / Timing Role: Tamper-resistant configuration vault; write-protected via EWDS/EWEN sequence after initial setup.

Use Value: 1M-cycle endurance supports >10,000 field updates over product lifetime while maintaining IEC 62304 traceability.

Use Scenario: Storing encrypted firmware patches and regional tax table updates in retail terminals with intermittent network connectivity.

IC Role / Device Role / Timing Role: Standalone update buffer decoupled from main flash; accessed only during secure boot validation.

Use Value: 4.5–5.5 V operation aligns with 5 V rail of legacy POS hardware; SOIC-8 footprint allows retrofit into existing designs.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
93C66A-I/SN	Same package and timing, but 512 × 8-bit (4 Kbit) organization; no ORG pin; identical V_CC and temp range.	Requires byte-oriented host software; unsuitable where 16-bit aligned data structures are used.	Select when system firmware uses 8-bit registers or legacy drivers written for x8 EEPROMs.
AT25040B-MAU-1.8	SPI interface (4-wire), 1.8–5.5 V operation, 2 MHz max clock, 5 ms write time; SOIC-8 package.	Needs SPI controller instead of Microwire; wider V_CC range enables battery-powered use but slower write speed.	Choose for new designs needing lower-voltage flexibility or SPI-native MCUs-requires PCB and firmware changes.

Compared with 93C66A-I/SN, the 93C66B-I/SN delivers native 16-bit data access reducing host CPU overhead by ~50% per write; versus AT25040B-MAU-1.8, it offers faster 2 ms writes and guaranteed Microwire compatibility but lacks sub-4.5 V operation.

Availability

93C66B-I/SN is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control modules, and medical infusion pumps requiring stable component supply with full traceability and long-lifecycle support.

Supply support for 93C66B-I/SN 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 93Cxx series was engineered specifically for cost-sensitive, space-constrained embedded systems needing robust nonvolatile storage without complex interface logic or external voltage regulation.

FAQ

What is the memory organization of the 93C66B-I/SN?

The 93C66B-I/SN has a fixed 256 × 16-bit (4 Kbit) organization. Unlike 'C' variants, it does not feature an ORG pin-its 16-bit word size is hardwired, eliminating external configuration and simplifying PCB layout. This matches the 93C66B entry in Microchip's DS21795E device selection table.

Does the 93C66B-I/SN support 3.3 V operation?

No, the 93C66B-I/SN does not support 3.3 V operation. Its specified V_CC range is strictly 4.5 V to 5.5 V, with power-on reset triggered at 3.8 V. Attempting operation below 4.5 V may result in undefined behavior or failed writes, as confirmed in Table 1-1 (D11) of DS21795E.

How is the Ready/Busy status monitored on the 93C66B-I/SN?

The Ready/Busy status is monitored via the DO pin: logic low indicates ongoing erase/write, logic high signals completion. To sample status, CS must be brought high for ≥250 ns after TCSL, then DO sampled on CLK edges. This behavior is defined in Section 2.4 and Figure 2-2 of DS21795E and applies identically to 93C66B-I/SN.

What is the maximum clock frequency supported by the 93C66B-I/SN?

The 93C66B-I/SN supports up to 3 MHz clock frequency when V_CC is 4.5–5.5 V, as specified in Table 1-2 (A1) of DS21795E. At this rate, READ and WRITE instructions complete in 20 clock cycles (≈6.7 µs active transfer time), excluding CS setup/hold and self-timed 2 ms programming delay.

Is the 93C66B-I/SN RoHS compliant and Pb-free?

Yes, the 93C66B-I/SN is RoHS compliant and Pb-free, with a Matte Tin (Sn) finish as stated in the Features section of DS21795E. The 'SN' package suffix denotes SOIC with Pb-free plating, and all packages in the 93XX66 family meet JEDEC J-STD-609 Category 1a requirements.

93C66B-I/SN Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width)

Packaging:: Tube

Product Status:: Active

Programmable:: Verified

Memory Type:: Non-Volatile

Memory Format:: EEPROM

Technology:: EEPROM

Memory Size:: 4Kbit

Memory Organization:: 256 x 16

Memory Interface:: Microwire

Clock Frequency:: 2 MHz

Write Cycle Time - Word, Page:: 2ms

Access Time:: -

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

93C66B-I/SN FAQ

1.How can I place an order for 93C66B-I/SN through Aetrix?

Please submit a Request for Quotation (RFQ) for 93C66B-I/SN on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 93C66B-I/SN reliable?

The price and inventory of 93C66B-I/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 93C66B-I/SN is usually 5 days.

3.What payment methods are accepted for 93C66B-I/SN?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 93C66B-I/SN transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 93C66B-I/SN?

93C66B-I/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 93C66B-I/SN order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 93C66B-I/SN?

For technical support, including 93C66B-I/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 93C66B-I/SN requirements.

6.How does Aetrix verify that 93C66B-I/SN is sourced from the original manufacturer or authorized distributors?

All 93C66B-I/SN products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 93C66B-I/SN meets industry standards.

7.What is the process for return or replacement of 93C66B-I/SN?

All 93C66B-I/SN units undergo pre-shipment inspection (PSI). If there is an issue with 93C66B-I/SN, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 93C66B-I/SN part is unused and in its original packaging.

Return procedure for 93C66B-I/SN:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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