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Microchip Technology 93C66AT-I/SN

Name: 93C66AT-I/SN
Brand: Microchip Technology
SKU: 93C66AT-I/SN
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 93C66AT-I/SN

Manufacturer:: Microchip Technology

Category:: Memory

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

Datasheet:: 93C66AT-I/SN.pdf

Description:: IC EEPROM 4KBIT MICROWIRE 8SOIC

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Product details

Overview

93C66AT-I/SN from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with 512 × 8-bit organization, designed for nonvolatile data storage in microcontroller-based systems. It operates over 4.5–5.5 V, supports Microwire-compatible 3-wire serial interface (CS/CLK/DI/DO), and delivers 1,000,000 erase/write cycles with >200-year data retention. Used in industrial control panels for calibration parameter storage.

For engineers reviewing the 93C66AT-I/SN datasheet, 93C66AT-I/SN pinout, 93C66AT-I/SN application, or 93C66AT-I/SN equivalent, key selection criteria include its fixed 8-bit word size, industrial temperature range (−40°C to +85°C), SOIC-8 package, Ready/Busy status signaling via DO, and compatibility with legacy Microwire host controllers requiring no protocol translation.

Technical Context

The 93C66AT-I/SN implements a synchronous serial interface with start-bit detection, opcode-driven command set (READ/WRITE/ERASE/ERAL/WRAL), and self-timed erase/write cycles initiated by CS falling edge (for 93C versions). It features hardware-level power-on/off data protection and requires EWEN/EWDS commands to enable/disable programming.

Unlike C-variant parts, this A-version device lacks an ORG pin - memory organization is permanently fixed at 512 × 8-bit. Its timing is optimized for V_CC ≥ 4.5 V: max clock frequency is 3 MHz, T_WC write cycle time is 2 ms, and ERAL/WRAL require V_CC ≥ 4.5 V for reliable operation.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	4 Kbit (512 × 8-bit) - fixed x8 organization; no ORG pin; no runtime word-size reconfiguration.
V_CC Range	4.5 V to 5.5 V - narrow supply window; incompatible with 3.3 V or 2.5 V systems without level shifting.
Interface	Microwire-compatible 3-wire serial (CS/CLK/DI/DO) - no SPI mode; requires start-bit detection and opcode framing.
Write Endurance	1,000,000 cycles - validated at 25°C, V_CC = 5.0 V; enables frequent field-updatable configuration storage.
Data Retention	>200 years - specified at 25°C; ensures long-term reliability in unpowered industrial deployments.
Temp Range	−40°C to +85°C (Industrial grade) - qualified for use in factory automation, HVAC, and motor drives.
Package	8-lead SOIC (SN) - standard footprint; pin-compatible with legacy 93C46/93C56 designs; RoHS-compliant matte tin finish.

Pinout & Package

8-lead SOIC (SN) package with standard 150-mil body width, gull-wing leads, and Pb-free matte tin plating. Pin 1 marked by laser dot or notch; pin 1 identifier located at top-left corner when viewed from top with marking side up.

Pin/Terminal	Circuit Role	Design Meaning
1 (CS)	Chip Select	Active-high enable; must be held high ≥250 ns between instructions; deselects device into standby but allows ongoing write completion.
2 (CLK)	Serial Clock	Synchronizes all data transfers; rising edge clocks in opcodes, addresses, and data; stoppable mid-sequence without corruption.
3 (DI)	Data Input	Accepts start bit, instruction opcodes, address bits, and write data; logic high on first CLK rising edge with CS high initiates command parsing.
4 (DO)	Data Output / Status	Outputs read data on rising CLK edges; also signals Ready/Busy (low = busy) during erase/write when CS is reasserted after TCSL.
5 (VSS)	Ground	Reference return path for all I/O and internal circuitry; must be low-impedance connection to system ground plane.
6 (NC)	No Connect	Internally unconnected; must be left floating or tied to VSS per layout best practice; not usable as ORG or any functional pin.
7 (NC)	No Connect	Same as Pin 6; dual NC pins confirm absence of ORG functionality in A-variant devices.
8 (VCC)	Power Supply	4.5–5.5 V only; internal POR circuit triggers at ~3.8 V; voltage below threshold disables all operations including reads.

Key Features

Feature	Design Value
Self-timed Erase/Write	Eliminates external timing control; 2 ms typical write cycle (T_WC) ensures deterministic firmware delay budgeting.
Automatic ERAL before WRAL	WRAL command internally executes full-array erase prior to write - no separate ERAL step required in host firmware.
Power-On/Off Data Protection	Hardware POR circuit blocks writes when V_CC < 3.8 V - prevents corruption during brown-out or hot-plug events.
Ready/Busy Status via DO	Enables polling-based write completion detection without interrupt lines; reduces MCU GPIO count and simplifies driver code.
Industry-standard 3-wire Interface	Direct drop-in replacement for legacy Microwire EEPROMs; avoids SPI-to-Microwire translation logic or software overhead.

Applications

Industrial Sensor Calibration	Legacy Industrial PLC Configuration
Use Scenario: Storing sensor offset/gain coefficients updated during field calibration of pressure transmitters. IC Role / Device Role / Timing Role: Nonvolatile parameter storage with infrequent writes and long-term retention; accessed via microcontroller's Microwire peripheral. Use Value: Enables field recalibration without battery-backed RAM; 1M endurance supports >100 calibrations/year over 10+ years.	Use Scenario: Holding I/O mapping tables and alarm thresholds in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Configuration EEPROM interfaced to 8051 or ARM Cortex-M0 host; accessed at startup and during parameter download. Use Value: Maintains user-defined logic behavior across power cycles; SOIC-8 footprint matches existing PCB layouts.
Automotive Body Control Module (BCM)	Point-of-Sale Terminal Settings
Use Scenario: Storing seat position memory and mirror angle presets in automotive BCMs. IC Role / Device Role / Timing Role: Parameter storage IC operating within −40°C to +85°C ambient; accessed via dedicated Microwire bus. Use Value: Meets industrial temp requirement; 200-year retention guarantees lifetime data integrity without refresh.	Use Scenario: Preserving tax rate tables, receipt formatting rules, and user PINs in retail POS terminals. IC Role / Device Role / Timing Role: Secure configuration storage with hardware write-protection (EWDS); accessed during boot and admin setup. Use Value: Prevents accidental overwrite during transaction processing; 4.5–5.5 V range aligns with 5 V rail in legacy terminal designs.

Industrial Sensor Calibration

Legacy Industrial PLC Configuration

Use Scenario: Storing sensor offset/gain coefficients updated during field calibration of pressure transmitters.

IC Role / Device Role / Timing Role: Nonvolatile parameter storage with infrequent writes and long-term retention; accessed via microcontroller's Microwire peripheral.

Use Value: Enables field recalibration without battery-backed RAM; 1M endurance supports >100 calibrations/year over 10+ years.

Use Scenario: Holding I/O mapping tables and alarm thresholds in DIN-rail mounted programmable logic controllers.

IC Role / Device Role / Timing Role: Configuration EEPROM interfaced to 8051 or ARM Cortex-M0 host; accessed at startup and during parameter download.

Use Value: Maintains user-defined logic behavior across power cycles; SOIC-8 footprint matches existing PCB layouts.

Automotive Body Control Module (BCM)

Point-of-Sale Terminal Settings

Use Scenario: Storing seat position memory and mirror angle presets in automotive BCMs.

IC Role / Device Role / Timing Role: Parameter storage IC operating within −40°C to +85°C ambient; accessed via dedicated Microwire bus.

Use Value: Meets industrial temp requirement; 200-year retention guarantees lifetime data integrity without refresh.

Use Scenario: Preserving tax rate tables, receipt formatting rules, and user PINs in retail POS terminals.

IC Role / Device Role / Timing Role: Secure configuration storage with hardware write-protection (EWDS); accessed during boot and admin setup.

Use Value: Prevents accidental overwrite during transaction processing; 4.5–5.5 V range aligns with 5 V rail in legacy terminal designs.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
93C66B-I/SN	16-bit organization (256 × 16); same V_CC, temp, and package; no ORG pin.	Requires host to send 16-bit words; incompatible with 8-bit firmware drivers.	Select only if system architecture mandates 16-bit data alignment and host controller supports x16 Microwire framing.
93LC66A-I/SN	Wider V_CC range (2.5–5.5 V); identical 512 × 8-bit organization and SOIC-8 package.	Supports 3.3 V systems directly; lower V_CC min enables mixed-voltage board designs.	Prefer for new designs targeting 3.3 V microcontrollers; retains pinout and instruction set compatibility.

Compared with 93C66B-I/SN, the 93C66AT-I/SN offers native 8-bit data access without packing overhead; compared with 93LC66A-I/SN, it sacrifices 3.3 V compatibility for tighter V_CC regulation tolerance and legacy 5 V system assurance.

Availability

93C66AT-I/SN is available at Aetrix Electronics and suitable for industrial control panels, automotive body electronics, and point-of-sale terminals requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for 93C66AT-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.

The 93Cxx series was engineered for cost-sensitive, low-power nonvolatile storage in resource-constrained embedded systems, emphasizing interoperability with legacy Microwire hosts and robustness in industrial environments.

FAQ

What is the memory organization of the 93C66AT-I/SN?

The 93C66AT-I/SN has a fixed 512 × 8-bit organization. As an "A" variant, it does not include an ORG pin and cannot be configured for 16-bit operation. This makes it functionally distinct from 93C66C parts, which require external logic on the ORG pin to select word size.

Does the 93C66AT-I/SN support 3.3 V operation?

No, the 93C66AT-I/SN requires a minimum V_CC of 4.5 V and is rated only for 4.5–5.5 V operation. For 3.3 V systems, consider the pin-compatible 93LC66A-I/SN, which supports 2.5–5.5 V and shares identical 512 × 8-bit organization and SOIC-8 packaging.

How is write protection implemented on the 93C66AT-I/SN?

Write protection is enforced through the EWEN (Erase/Write Enable) and EWDS (Erase/Write Disable) instructions. The device powers up in EWDS mode; an EWEN command must precede any ERASE or WRITE operation. After each write, issuing EWDS restores protection - a critical step to prevent accidental overwrites in the 93C66AT-I/SN.

What is the maximum clock frequency supported by the 93C66AT-I/SN?

The 93C66AT-I/SN supports a maximum clock frequency of 3 MHz when V_CC is between 4.5 V and 5.5 V. At this speed, timing parameters such as T_CKH (clock high time) and T_CKL (clock low time) are guaranteed to meet 200 ns and 100 ns respectively, enabling high-throughput configuration updates in the 93C66AT-I/SN.

Can the 93C66AT-I/SN be used as a direct replacement for the 93C46?

Yes - the 93C66AT-I/SN is pin-compatible and instruction-compatible with the 93C46 in SOIC-8 (SN) package, offering double the memory capacity (4 Kbit vs. 2 Kbit) while maintaining identical Microwire protocol, timing, and voltage requirements. Firmware requiring 93C46 can typically use the 93C66AT-I/SN without modification, provided address space usage stays within 512 bytes.

93C66AT-I/SN Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

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

Packaging:: Tape & Reel (TR)

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:: 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

93C66AT-I/SN FAQ

1.How can I place an order for 93C66AT-I/SN through Aetrix?

Please submit a Request for Quotation (RFQ) for 93C66AT-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 93C66AT-I/SN reliable?

The price and inventory of 93C66AT-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 93C66AT-I/SN is usually 5 days.

3.What payment methods are accepted for 93C66AT-I/SN?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 93C66AT-I/SN transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 93C66AT-I/SN?

93C66AT-I/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 93C66AT-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 93C66AT-I/SN?

For technical support, including 93C66AT-I/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 93C66AT-I/SN requirements.

6.How does Aetrix verify that 93C66AT-I/SN is sourced from the original manufacturer or authorized distributors?

All 93C66AT-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 93C66AT-I/SN meets industry standards.

7.What is the process for return or replacement of 93C66AT-I/SN?

All 93C66AT-I/SN units undergo pre-shipment inspection (PSI). If there is an issue with 93C66AT-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 93C66AT-I/SN part is unused and in its original packaging.

Return procedure for 93C66AT-I/SN:

1.Submit a request within 90 days.

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

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