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Microchip Technology 93C66AT-I/ST
- Part No.:
- 93C66AT-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
93C66AT-I/ST.pdf
- Description:
- IC EEPROM 4KBIT MICROWIRE 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,873
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Product details
Overview
93C66AT-I/ST from Microchip Technology Inc. is a 4 Kbit low-voltage serial EEPROM with 512 × 8-bit organization, operating over 4.5–5.5 V supply and rated for industrial temperature (−40°C to +85°C). It uses Microwire-compatible 3-wire serial interface (CS, CLK, DI, DO), supports self-timed erase/write cycles, and delivers 1,000,000 endurance cycles with >200-year data retention. It is used in embedded system configuration storage where compact nonvolatile memory with robust power-on/off protection is required.
For engineers reviewing the 93C66AT-I/ST datasheet, 93C66AT-I/ST pinout, 93C66AT-I/ST application, or 93C66AT-I/ST equivalent, key selection considerations include its fixed 8-bit word size (no ORG pin), TSSOP-8 package, 4.5–5.5 V operation, industrial-grade temperature range, and Microwire timing compliance - especially critical for legacy microcontroller peripheral interfaces requiring deterministic clock setup/hold and status polling via DO.
Technical Context
The 93C66AT-I/ST implements a synchronous Microwire-compatible serial protocol with start-bit detection, opcode-driven instruction set (READ, WRITE, ERASE, ERAL, WRAL), and Ready/Busy status signaled on the DO pin during programming. Its internal logic requires CS ≥ 250 ns low between instructions and supports sequential read when CS remains high.
Unlike C-variant parts, this A-version device has no ORG pin - it is permanently configured for 8-bit organization. Write operations initiate on the falling edge of CS (after final data bit), and all erase/write functions require prior execution of EWEN; the device powers up in EWDS mode for data integrity.
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. |
| VCC Range | 4.5 V to 5.5 V - incompatible with 3.3 V or 2.5 V systems; POR threshold at 3.8 V ensures reliable power-up protection. |
| Interface | Microwire 3-wire serial (CS, CLK, DI, DO) - no SPI mode; requires start-bit detection and strict timing per DS21795E Table 1-2. |
| Write Cycle Time | 2 ms typical - self-timed; no external delay needed; initiated by CS falling edge after last data bit. |
| Endurance & Retention | 1,000,000 erase/write cycles and >200 years data retention - validated at 25°C, VCC = 5.0 V; suitable for infrequent but mission-critical parameter storage. |
| Temperature Range | Industrial: −40°C to +85°C - qualified per Microchip's I-temp specification; not automotive-qualified (E-temp). |
| Package | TSSOP-8 (ST suffix) - 4.4 mm × 3.0 mm body, 0.65 mm pitch; RoHS-compliant matte tin finish. |
Pinout & Package
TSSOP-8 package (ST suffix), 4.4 mm × 3.0 mm body, 0.65 mm lead pitch, Pb-free matte tin finish. Pin 1 marked by laser dot or notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (CS) | Chip Select | Active-high enable; must be held ≥250 ns low between instructions; falling edge initiates write/erase after data load. |
| 2 (CLK) | Serial Clock | Positive-edge synchronized; clocks opcode, address, and data; stoppable at any level; no clocking required during self-timed write. |
| 3 (DI) | Data Input | Accepts start bit, opcode, address, and write data; high impedance when not selected; requires pull-up if shared with DO. |
| 4 (DO) | Data Output / Status | Outputs read data on rising CLK edge; signals Ready/Busy (low = busy) when CS is high post-instruction; high-Z when CS low. |
| 5 (VSS) | Ground | Reference for all I/O and internal logic; must be low-impedance connection to minimize noise coupling into serial interface. |
| 6 (NC) | No Connect | No internal connection; must be left floating or tied to VSS per layout best practice; not usable as strap or control. |
| 7 (ORG) | Organization | Not present on A/B variants - pin 7 is NC; only C-variants use ORG to select x8/x16; irrelevant for 93C66AT-I/ST. |
| 8 (VCC) | Power Supply | 4.5–5.5 V only; internal POR circuit triggers at 3.8 V; decoupling capacitor (0.1 µF ceramic) required within 5 mm. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed Erase/Write | Eliminates need for external timing control or software delays; cycle completes autonomously in ≤2 ms; frees MCU resources during programming. |
| Power-On/Off Data Protection | Hardware POR circuit disables writes below 3.8 V; prevents corruption during brown-out or uncontrolled power ramp; no external supervisor IC required. |
| Ready/Busy Status on DO | Enables efficient polling without dedicated status lines; allows MCU to execute other tasks while waiting for write completion; avoids fixed timeout delays. |
| Automatic Erase All before Write All | WRAL instruction includes implicit ERAL - simplifies full-memory initialization; eliminates separate erase command sequence; reduces firmware complexity. |
| Erase/Write Enable/Disable (EWEN/EWDS) | Prevents accidental writes: device powers up locked (EWDS); explicit EWEN required before each programming session; recommended to issue EWDS post-write. |
Applications
| Industrial Control Configuration | Legacy Microcontroller Peripheral Storage |
|---|---|
Use Scenario: Storing calibration coefficients, sensor offsets, and operational thresholds in PLC I/O modules subject to frequent power cycling. IC Role / Device Role / Timing Role: Nonvolatile parameter register accessed via Microwire interface during boot or maintenance mode; supports sequential read for bulk coefficient loading. Use Value: 1M endurance ensures >10 years of field updates at 100 writes/year; >200-year retention guarantees parameter persistence across equipment lifetime without battery backup. | Use Scenario: Holding bootloader configuration flags and hardware revision IDs in 8-bit microcontrollers (e.g., PIC16F, 8051 derivatives) with native Microwire peripherals. IC Role / Device Role / Timing Role: Serial configuration memory mapped to MCU's dedicated Microwire port; leverages built-in start-bit detection and opcode decoding to minimize firmware overhead. Use Value: Fixed 4.5–5.5 V operation matches legacy 5 V system rails; TSSOP-8 footprint enables drop-in replacement of obsolete 93C46/93C56 parts without PCB redesign. |
| Power Meter Firmware Metadata | Medical Device Calibration Log |
Use Scenario: Recording firmware version, meter ID, and last calibration timestamp in ANSI C12.20-compliant electricity meters with strict EMC and reliability requirements. IC Role / Device Role / Timing Role: Secure metadata store accessed during meter startup and firmware update verification; protected by EWEN/EWDS lock sequence. Use Value: Industrial temp rating ensures operation inside sealed meter enclosures up to +85°C ambient; RoHS-compliant packaging meets global regulatory mandates. | Use Scenario: Archiving calibration constants and sensor validation logs in portable diagnostic devices (e.g., pulse oximeters) requiring traceable, tamper-resistant storage. IC Role / Device Role / Timing Role: Tamper-evident configuration memory; write-protection enforced by hardware POR and EWDS lock; DO status polling confirms write integrity before clinical use. Use Value: 2 ms write time enables fast calibration save during device power-down; >200-year retention satisfies FDA 21 CFR Part 11 long-term recordkeeping requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 93LC66AT-I/ST | Wider VCC range (2.5–5.5 V); same 512×8 organization, TSSOP-8, and industrial temp rating; supports lower-voltage operation. | Enables direct use in mixed 3.3 V/5 V systems; eliminates level-shifting for 3.3 V MCUs; retains identical pinout and instruction set. | Select when system operates below 4.5 V or requires dual-rail compatibility; verify POR behavior (1.5 V threshold) aligns with system power sequencing. |
| 93AA66AT-I/ST | Widest VCC range (1.8–5.5 V); same 512×8 organization and TSSOP-8 package; identical timing and instruction set. | Supports ultra-low-power battery-backed applications down to 1.8 V; compatible with modern energy-efficient MCUs (e.g., PIC16LF, MSP430). | Select for battery-powered or wide-input industrial designs; confirm that 1.8 V minimum VCC meets system brown-out detector thresholds. |
Compared with 93LC66AT-I/ST and 93AA66AT-I/ST, the 93C66AT-I/ST offers narrower voltage tolerance but higher immunity to transient overvoltage (7.0 V absolute max), making it preferable in noisy 5 V environments where supply regulation is robust but ESD risk is elevated.
Availability
93C66AT-I/ST is available at Aetrix Electronics and suitable for industrial control configuration, legacy microcontroller peripheral storage, and power meter firmware metadata applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for 93C66AT-I/ST 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 Flash-IP solutions, headquartered in Chandler, Arizona, with global design, manufacturing, and sales operations.
The 93Cxx series was designed specifically for cost-sensitive, space-constrained embedded systems requiring reliable, low-pin-count serial EEPROM with Microwire compatibility and robust data integrity features.
FAQ
What is the memory organization and capacity of the 93C66AT-I/ST?
The 93C66AT-I/ST provides 4 Kbit of serial EEPROM memory organized as 512 words × 8 bits. It is an A-variant device with no ORG pin, so the 8-bit word size is fixed and cannot be reconfigured to 16-bit. This matches legacy Microwire systems expecting byte-oriented access without address extension logic.
Does the 93C66AT-I/ST support 3.3 V operation?
No, the 93C66AT-I/ST does not support 3.3 V operation. Its specified VCC range is strictly 4.5 V to 5.5 V, with a power-on reset threshold of 3.8 V. For 3.3 V systems, consider the functionally identical 93LC66AT-I/ST (2.5–5.5 V) or 93AA66AT-I/ST (1.8–5.5 V), both in TSSOP-8 and pin-compatible.
How is write protection implemented on the 93C66AT-I/ST?
Write protection on the 93C66AT-I/ST is implemented via hardware POR and software-controlled EWEN/EWDS commands. The device powers up in EWDS (Erase/Write Disable) mode, blocking all programming until an explicit EWEN instruction is issued. After each write, issuing EWDS restores protection - a critical step to prevent accidental corruption during noise events or power transients.
What package type does the 93C66AT-I/ST use, and what are its key mechanical dimensions?
The 93C66AT-I/ST uses a TSSOP-8 package (ST suffix), measuring 4.4 mm × 3.0 mm with 0.65 mm lead pitch. It features a standard JEDEC MO-153 variant footprint, RoHS-compliant matte tin plating, and laser-marked pin 1 identification. The exposed pad is not present - unlike MSOP or DFN variants - simplifying thermal and assembly validation.
Can the 93C66AT-I/ST be used interchangeably with the 93C46 or 93C56?
The 93C66AT-I/ST is not a direct drop-in replacement for 93C46 (1 Kbit) or 93C56 (2 Kbit) due to doubled memory size (4 Kbit) and updated timing parameters (e.g., 2 ms write cycle vs. 5 ms for older parts). While pinout and instruction set are compatible, firmware must validate address range (A0–A8 vs. A0–A7) and adjust timing margins per DS21795E AC specs to ensure reliable operation.
93C66AT-I/ST Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not 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-TSSOP
93C66AT-I/ST FAQ
1.How can I place an order for 93C66AT-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 93C66AT-I/ST 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/ST reliable?
The price and inventory of 93C66AT-I/ST 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/ST is usually 5 days.
3.What payment methods are accepted for 93C66AT-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 93C66AT-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 93C66AT-I/ST?
93C66AT-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 93C66AT-I/ST 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/ST?
For technical support, including 93C66AT-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 93C66AT-I/ST requirements.
6.How does Aetrix verify that 93C66AT-I/ST is sourced from the original manufacturer or authorized distributors?
All 93C66AT-I/ST 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/ST meets industry standards.
7.What is the process for return or replacement of 93C66AT-I/ST?
All 93C66AT-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 93C66AT-I/ST, 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/ST part is unused and in its original packaging.
Return procedure for 93C66AT-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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