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

Microchip Technology 93AA66A-I/SN

Name: 93AA66A-I/SN
Brand: Microchip Technology
SKU: 93AA66A-I/SN
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 93AA66A-I/SN

Manufacturer:: Microchip Technology

Category:: Memory

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

Datasheet:: 93AA66A-I/SN.pdf

Description:: IC EEPROM 4KBIT MICROWIRE 8SOIC

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Product details

Overview

93AA66A-I/SN from Microchip Technology Inc. is a 4 Kbit (512 × 8-bit) low-voltage serial EEPROM with Microwire-compatible 3-wire interface, 1.8–5.5 V supply range, and industrial temperature rating (–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, sensor calibration retention, and firmware parameter backup.

For engineers reviewing the 93AA66A-I/SN datasheet, 93AA66A-I/SN pinout, 93AA66A-I/SN application, or 93AA66A-I/SN equivalent, key selection criteria include its dedicated 8-bit organization (no ORG pin), 1 million erase/write endurance, >200-year data retention, and compatibility with microcontroller SPI-like serial masters requiring minimal I/O resources and robust nonvolatile memory at ultra-low standby current (1 µA).

Technical Context

This device implements a synchronous serial interface with CS, CLK, and DI/DO pins operating in Microwire protocol mode. All instructions - READ, WRITE, ERASE, ERAL, WRAL, EWEN, EWDS - are initiated by a Start bit followed by opcode, address, and data fields clocked on CLK rising edges. The DO pin serves dual function: serial data output during READ and Ready/Busy status indicator during programming.

Internal logic enforces power-on write protection: the device powers up in EWDS (Erase/Write Disable) state, requiring explicit EWEN before any programming operation. VCC brown-out detection (1.5 V threshold) prevents inadvertent writes during power ramp-up or dropout, and automatic ERAL precedes WRAL to ensure full-array readiness before bulk write.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory size	4 Kbit (512 words × 8 bits) - fixed x8 organization; no ORG pin; eliminates external configuration logic.
V_CC range	1.8 V to 5.5 V - supports direct interfacing with 1.8 V, 3.3 V, and 5 V microcontrollers without level shifters.
Endurance	1,000,000 erase/write cycles - enables frequent field updates in telemetry loggers or adaptive control systems.
Data retention	>200 years at 25°C - ensures long-term reliability in unattended infrastructure monitoring devices.
Standby current	1 µA (I-temp) - minimizes battery drain in always-on IoT edge nodes with infrequent parameter writes.
Write cycle time	6 ms typical (T_WC) - defines minimum interval between successive WRITE commands; impacts real-time logging latency.
Interface	3-wire Microwire-compatible (CS, CLK, DI/DO) - reduces MCU pin count vs. SPI; shares DI/DO line for compact PCB layout.

Pinout & Package

93AA66A-I/SN is packaged in 8-lead SOIC (SN), with pin 1 marked by laser dot. Pin functions are standardized across SOIC, PDIP, TSSOP, and MSOP variants per Microchip DS21795E.

Pin/Terminal	Circuit Role	Design Meaning
CS	Chip Select	Active-high enable; must be held ≥250 ns low between instructions; initiates self-timed write on falling edge (93AA/93LC).
CLK	Serial Clock	Synchronizes all data transfers; rising edge clocks in opcode/address/data; stoppable mid-sequence for master flexibility.
DI	Data Input	Receives Start bit, instruction opcodes, addresses, and write data; shared with DO in bidirectional configurations (requires series resistor).
DO	Data Output / Status	Outputs read data or Ready/Busy status (low = busy); enters High-Z when CS goes low; requires CS high ≥250 ns to sample status.
VSS	Ground	Reference for all digital and analog circuitry; must be low-impedance connection to minimize noise coupling into DO timing.
NC	No internal connection	Pin 7 in SOIC/SN package - left unconnected; not bonded internally; no routing or termination required.
VCC	Power Supply	1.8–5.5 V supply; includes internal voltage detect (1.5 V) for power-on write protection; bypass capacitor mandatory.
ORG	Organization select	Not present on 93AA66A - permanently configured for 8-bit mode; pin 6 is NC (no internal connection).

Key Features

Feature	Design Value
Self-timed erase/write	Eliminates need for external timing control or polling delays beyond T_WC/T_EC/T_WL; simplifies firmware driver implementation.
Automatic ERAL before WRAL	Guarantees full-array erase prior to bulk write - prevents partial-write corruption without software intervention.
Power-on/off data protection	Hardware-enforced write inhibition below 1.5 V V_CC - prevents bit corruption during brown-out or battery depletion.
Ready/Busy status on DO	Enables efficient polling instead of fixed-delay waits; reduces average write latency in interrupt-driven systems.
Sequential read mode	Allows continuous address increment with CS held high - accelerates bulk read of configuration blocks or lookup tables.

Applications

Industrial Sensor Calibration Storage	Embedded System Configuration Memory
Use Scenario: Storing factory-calibrated coefficients and offset values for temperature, pressure, and humidity sensors in programmable logic controllers. IC Role / Device Role / Timing Role: Nonvolatile parameter register accessed at power-up and during field recalibration; operates at 1–10 kHz CLK during maintenance mode. Use Value: Ensures measurement accuracy over product lifetime using >200-year data retention and 1M-cycle endurance for periodic recalibration.	Use Scenario: Holding boot-time configuration flags, network MAC addresses, and user-defined settings in networked HVAC controllers. IC Role / Device Role / Timing Role: Serial configuration store interfaced to MCU GPIOs; accessed during initialization and settings update; uses sequential read for fast parameter load. Use Value: Reduces BOM cost vs. larger SPI Flash; 1 µA standby current extends battery life in wireless thermostat modules.
Firmware Parameter Backup	Medical Device Safety Settings
Use Scenario: Retaining runtime-adjusted PID gains, alarm thresholds, and operational limits in motor drive inverters after power cycling. IC Role / Device Role / Timing Role: Write-once-per-session parameter archive; WRITE operations triggered only on user save or fault recovery; CS toggled per command. Use Value: Guarantees deterministic restore behavior using hardware write-protection (EWDS/EWEN) and brown-out immunity.	Use Scenario: Storing certified safety-critical parameters (e.g., maximum dose limits, calibration locks) in portable infusion pumps. IC Role / Device Role / Timing Role: Tamper-resistant configuration vault; accessed only by secure bootloader; requires verified write sequence (EWEN → WRITE → EWDS). Use Value: Meets IEC 62304 requirements via hardware-enforced write disable and >200-year retention for audit trail integrity.

Industrial Sensor Calibration Storage

Embedded System Configuration Memory

Use Scenario: Storing factory-calibrated coefficients and offset values for temperature, pressure, and humidity sensors in programmable logic controllers.

IC Role / Device Role / Timing Role: Nonvolatile parameter register accessed at power-up and during field recalibration; operates at 1–10 kHz CLK during maintenance mode.

Use Value: Ensures measurement accuracy over product lifetime using >200-year data retention and 1M-cycle endurance for periodic recalibration.

Use Scenario: Holding boot-time configuration flags, network MAC addresses, and user-defined settings in networked HVAC controllers.

IC Role / Device Role / Timing Role: Serial configuration store interfaced to MCU GPIOs; accessed during initialization and settings update; uses sequential read for fast parameter load.

Use Value: Reduces BOM cost vs. larger SPI Flash; 1 µA standby current extends battery life in wireless thermostat modules.

Firmware Parameter Backup

Medical Device Safety Settings

Use Scenario: Retaining runtime-adjusted PID gains, alarm thresholds, and operational limits in motor drive inverters after power cycling.

IC Role / Device Role / Timing Role: Write-once-per-session parameter archive; WRITE operations triggered only on user save or fault recovery; CS toggled per command.

Use Value: Guarantees deterministic restore behavior using hardware write-protection (EWDS/EWEN) and brown-out immunity.

Use Scenario: Storing certified safety-critical parameters (e.g., maximum dose limits, calibration locks) in portable infusion pumps.

IC Role / Device Role / Timing Role: Tamper-resistant configuration vault; accessed only by secure bootloader; requires verified write sequence (EWEN → WRITE → EWDS).

Use Value: Meets IEC 62304 requirements via hardware-enforced write disable and >200-year retention for audit trail integrity.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
93LC66A-I/SN	Same 4 Kbit x8 organization, but 2.5–5.5 V V_CC range and supports both Industrial and Extended temp (–40°C to +125°C).	Required where automotive-grade temperature operation or higher minimum V_CC is mandated; not suitable for 1.8 V systems.	Select 93LC66A-I/SN if operating above 2.5 V and requiring extended temperature support; otherwise 93AA66A-I/SN offers broader low-voltage compatibility.
AT25040B-SSHL-T	4 Kbit SPI EEPROM (4-wire), 1.8–5.5 V, 20 MHz max CLK, 5 ms write cycle, and built-in write protect pin.	Requires dedicated SI/SO pins (no shared DI/DO); supports faster throughput and hardware WP pin for enhanced security.	Choose AT25040B-SSHL-T when SPI-native interface, higher speed, or dedicated write protect is prioritized over pin count minimization.

Compared with 93LC66A-I/SN, 93AA66A-I/SN enables 1.8 V operation critical for battery-powered designs, while AT25040B-SSHL-T trades pin efficiency for SPI compatibility and faster write performance - making 93AA66A-I/SN optimal for resource-constrained 1.8–3.3 V embedded systems needing minimal I/O and proven Microwire interoperability.

Availability

93AA66A-I/SN is available at Aetrix Electronics and suitable for industrial sensor calibration storage, embedded system configuration memory, and firmware parameter backup requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for 93AA66A-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 microcontroller, analog, and memory solutions, headquartered in Chandler, Arizona, with global design, manufacturing, and sales operations.

The 93XX series EEPROMs - including 93AA66A-I/SN - were designed specifically for low-power, space-constrained embedded applications requiring reliable, low-voltage serial nonvolatile memory with minimal external components and robust data integrity.

FAQ

What is the memory organization of the 93AA66A-I/SN?

The 93AA66A-I/SN has a fixed 512 × 8-bit (4 Kbit) organization with no ORG pin. Unlike 'C' variants, it does not support x16 mode - all instructions and data transfers operate exclusively in 8-bit format, simplifying firmware development and eliminating external configuration logic.

Does the 93AA66A-I/SN require an external pull-up resistor on the DO pin?

No external pull-up is required on the DO pin of the 93AA66A-I/SN. The device drives DO actively during READ and Ready/Busy status reporting. However, if DI and DO are shorted for bidirectional use, a series resistor (typically 100–470 Ω) is required to prevent bus conflict during the dummy zero phase of READ operations.

How does the 93AA66A-I/SN handle power loss during a write operation?

The 93AA66A-I/SN incorporates hardware power-loss protection: its internal voltage detector disables all write operations when V_CC falls below ~1.5 V. This prevents partial writes or data corruption during brown-out conditions, ensuring that only fully completed erase/write cycles commit to memory - a critical feature for safety-critical firmware parameter storage.

What is the purpose of the EWEN and EWDS commands in the 93AA66A-I/SN?

The EWEN (Erase/Write Enable) and EWDS (Erase/Write Disable) commands provide software-controlled write protection for the 93AA66A-I/SN. The device powers up in EWDS mode, blocking all programming until EWEN is issued. After each WRITE or ERASE, executing EWDS restores protection - preventing accidental overwrites due to noise or firmware errors.

Can the 93AA66A-I/SN be used with a standard SPI interface?

The 93AA66A-I/SN uses a Microwire-compatible 3-wire interface (CS, CLK, DI/DO), not standard SPI. While functionally similar, it lacks separate SI/SO lines and uses different instruction opcodes and timing (e.g., Start bit detection, 12/20/27 clock cycles per instruction). Direct SPI hardware compatibility is not guaranteed without firmware adaptation to Microwire protocol specifics.

93AA66A-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:: 512 x 8

Memory Interface:: Microwire

Clock Frequency:: 2 MHz

Write Cycle Time - Word, Page:: 6ms

Access Time:: -

Voltage - Supply:: 1.8V ~ 5.5V

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

93AA66A-I/SN FAQ

1.How can I place an order for 93AA66A-I/SN through Aetrix?

Please submit a Request for Quotation (RFQ) for 93AA66A-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 93AA66A-I/SN reliable?

The price and inventory of 93AA66A-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 93AA66A-I/SN is usually 5 days.

3.What payment methods are accepted for 93AA66A-I/SN?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 93AA66A-I/SN transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 93AA66A-I/SN?

93AA66A-I/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 93AA66A-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 93AA66A-I/SN?

For technical support, including 93AA66A-I/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 93AA66A-I/SN requirements.

6.How does Aetrix verify that 93AA66A-I/SN is sourced from the original manufacturer or authorized distributors?

All 93AA66A-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 93AA66A-I/SN meets industry standards.

7.What is the process for return or replacement of 93AA66A-I/SN?

All 93AA66A-I/SN units undergo pre-shipment inspection (PSI). If there is an issue with 93AA66A-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 93AA66A-I/SN part is unused and in its original packaging.

Return procedure for 93AA66A-I/SN:

1.Submit a request within 90 days.

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

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