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Microchip Technology 25LC640AT-E/ST
- Part No.:
- 25LC640AT-E/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25LC640AT-E/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,740
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Product details
Overview
25LC640AT-E/ST from Microchip Technology Inc. is a 64-Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and industrial-temperature operation (–40°C to +85°C). It supports up to 10 MHz clock frequency at 4.5–5.5V, features hardware write protection via WP pin and STATUS register, and delivers 1 million erase/write cycles with >200-year data retention. It is used in microcontroller-based systems for firmware parameter storage, calibration data logging, and configuration backup.
For engineers reviewing the 25LC640AT-E/ST datasheet, 25LC640AT-E/ST pinout, 25LC640AT-E/ST application, or 25LC640AT-E/ST equivalent, key selection criteria include VCC range (2.5V–5.5V), SPI interface compatibility, page-write capability, HOLD functionality for interrupt-safe operation, and AEC-Q100-qualified variants for automotive-grade reliability validation.
Technical Context
The 25LC640AT-E/ST implements a standard SPI Mode 0,0 (CPOL=0, CPHA=0) interface with separate SI and SO lines, requiring CS, SCK, SI, SO, WP, HOLD, VCC, and VSS connections. Its internal architecture includes an 8-bit instruction register, page latches, and high-voltage generation circuitry for EEPROM programming.
It supports sequential read, byte/page write, status register access (RDSR/WRSR), and hardware-controlled block protection (BP0/BP1 bits). The HOLD pin enables pausing of ongoing SPI transfers without resetting the sequence, and the WP pin-when enabled via WPEN bit-prevents writes to nonvolatile STATUS register bits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit), directly addressable via 16-bit SPI command addressing |
| Page Size | 32 bytes - maximum contiguous write length without crossing physical page boundary |
| Max Clock Frequency | 10 MHz at VCC = 4.5–5.5V - enables fast configuration reads in real-time control loops |
| Write Endurance | 1,000,000 erase/write cycles - supports frequent recalibration or event-logging applications |
| Data Retention | >200 years at +85°C - ensures long-term integrity of stored calibration or security keys |
| Operating Voltage | 2.5V–5.5V - compatible with 3.3V and 5V microcontroller I/O domains without level shifting |
| Temperature Range | –40°C to +85°C (Industrial) - validated for deployment in industrial PLCs and motor drives |
Pinout & Package
25LC640AT-E/ST is packaged in an 8-lead SOIC (SN) with 150-mil body width and standard JEDEC MS-012AC footprint. Pin 1 is marked with a beveled corner or dot; package is RoHS-compliant and Pb-free.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable: asserts device into active mode; rising edge initiates internal write cycle after valid write sequence |
| SO | Serial Output | Tri-state open-drain output; data shifted out on falling edge of SCK during read operations |
| WP | Write-Protect Input | Hardware lock for STATUS register when WPEN=1; low state blocks nonvolatile bit writes |
| VSS | Ground Reference | Primary return path for all internal logic and memory array current |
| SI | Serial Input | Latches instruction, address, and data on rising edge of SCK; MSB-first protocol |
| SCK | Serial Clock Input | Synchronizes all SPI transactions; defines timing for SI sampling and SO update |
| HOLD | Hold Control Input | Pauses ongoing SPI transfer when pulled low while SCK is low; preserves internal state |
| VCC | Supply Voltage | Power input for core logic and EEPROM programming circuitry; requires local 0.1 µF decoupling |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Selectable protection of none, upper 1/4, upper 1/2, or full memory array via BP0/BP1 bits |
| Self-Timed Write Cycle | Internal 5 ms max write completion - eliminates need for external timeout polling in host firmware |
| HOLD Functionality | Enables host CPU to service higher-priority interrupts mid-transaction without data loss or reinitialization |
| Power-On Write Protection | Write enable latch resets at power-up; prevents accidental writes during brown-out or reset conditions |
| ESD Robustness | >4000V HBM - enhances reliability in handling-sensitive industrial assembly environments |
Applications
| Industrial Sensor Calibration | Automotive ECU Configuration |
|---|---|
Use Scenario: Storing factory-calibrated sensor offset/gain coefficients and temperature compensation tables in programmable logic controllers. IC Role / Device Role / Timing Role: Nonvolatile configuration storage accessed during system boot and runtime recalibration routines. Use Value: Enables field-upgradable calibration without firmware reflashing; 1M endurance supports periodic recalibration over 10+ years. |
Use Scenario: Holding vehicle-specific tuning parameters, VIN-linked settings, and diagnostic trouble code (DTC) history in engine control units. IC Role / Device Role / Timing Role: SPI-configurable persistent memory for safety-critical configuration data with hardware write-locking. Use Value: WP pin + WPEN bit prevents unauthorized modification during CAN bus updates; AEC-Q100 qualification ensures operation under engine bay thermal stress. |
| Medical Device Settings Backup | Smart Meter Firmware Parameters |
Use Scenario: Retaining user-defined therapy profiles, alarm thresholds, and audit logs in portable infusion pumps and dialysis monitors. IC Role / Device Role / Timing Role: Secure, low-power EEPROM interfaced to ARM Cortex-M microcontrollers via SPI. Use Value: >200-year data retention guarantees integrity of life-critical settings across product lifetime; standby current ≤1 µA extends battery life. |
Use Scenario: Storing tariff schedules, metering constants, and communication credentials in ANSI C12.22-compliant electricity meters. IC Role / Device Role / Timing Role: Tamper-resistant configuration store with block-level protection against firmware corruption. Use Value: BP0/BP1 bits allow independent locking of tariff tables vs. operational registers; 10 MHz interface supports rapid credential updates during OTA provisioning. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA640AT-I/ST | Wider VCC range (1.8V–5.5V); identical pinout, timing, and memory map | Better suited for mixed-voltage systems with 1.8V logic domains or battery-powered designs | Select when operating below 2.5V is required; otherwise 25LC640AT-E/ST offers tighter VCC min spec for noise margin in 3.3V/5V systems |
| AT25DF641-MAU-T | 64 Mbit density, quad-SPI interface, faster 80 MHz clock; different command set and package (8-lead SOIC) | Targeted at high-speed firmware storage, not parameter/configuration EEPROM use cases | Not drop-in; requires firmware rewrite and layout review; choose only when >64 Kbit capacity or quad-SPI bandwidth is mandatory |
Compared with 25AA640AT-I/ST, the 25LC640AT-E/ST provides higher noise immunity in 3.3V/5V systems due to its 2.5V minimum VCC, while AT25DF641-MAU-T serves fundamentally different high-density code storage needs and cannot replace it in configuration EEPROM roles.
Availability
25LC640AT-E/ST is available at Aetrix Electronics and suitable for industrial sensor calibration, automotive ECU configuration, and medical device settings backup requiring stable component supply and long-term lifecycle support.
Supply support for 25LC640AT-E/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 U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for embedded control applications.
The 25LC640A family was designed specifically for reliable, low-power configuration storage in resource-constrained microcontroller systems, emphasizing SPI simplicity, hardware write protection, and industrial-grade reliability.
FAQ
What is the operating voltage range for the 25LC640AT-E/ST?
The 25LC640AT-E/ST operates from 2.5V to 5.5V. This range ensures compatibility with both 3.3V and 5V microcontroller I/O interfaces without level-shifting circuitry. Operation below 2.5V is not guaranteed and may result in unreliable write cycles or STATUS register access failures. The device's DC characteristics-including ICC Read, ICC Write, and VOL-are fully specified across this voltage window per DS20001830G.
Does the 25LC640AT-E/ST support page write operations?
Yes, the 25LC640AT-E/ST supports page write operations of up to 32 bytes within a single physical page boundary. Attempting to write across a page boundary causes wraparound to the start of the same page, potentially overwriting prior data. Host firmware must validate address alignment before initiating multi-byte writes. Each page write still requires one CS high-to-low transition to initiate the internal 5 ms write cycle.
How does the HOLD pin function on the 25LC640AT-E/ST?
The HOLD pin on the 25LC640AT-E/ST suspends ongoing SPI communication without resetting the internal state. To activate HOLD, the pin must be driven low while SCK is low; SO, SI, and SCK enter high-impedance states, and input transitions are ignored except for CS. Resuming requires bringing HOLD high while SCK remains low. This allows microcontrollers to service time-critical interrupts mid-transfer without losing context or requiring retransmission.
What write protection mechanisms does the 25LC640AT-E/ST provide?
The 25LC640AT-E/ST provides three-tiered write protection: (1) software-controlled via WREN/WRDI instructions and WEL bit, (2) hardware-enforced via WP pin when WPEN=1 in the STATUS register, and (3) block-level via BP0/BP1 bits enabling protection of none, upper 1/4, upper 1/2, or full memory array. These layers operate independently-e.g., WP low blocks STATUS register writes even if WEL=1-and are documented in Table 5-1 of DS20001830G.
Is the 25LC640AT-E/ST qualified for automotive applications?
No-the 25LC640AT-E/ST is rated for Industrial temperature range (–40°C to +85°C) and is not AEC-Q100 qualified. For automotive use, Microchip offers the 25LC640A variant with "E" suffix (e.g., 25LC640AE/ST) rated to –40°C to +125°C and AEC-Q100 Grade 3 qualified. The "T-E/ST" suffix in 25LC640AT-E/ST denotes tape-and-reel packaging and Industrial temp grade-not automotive qualification.
25LC640AT-E/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:
- 64Kbit
- Memory Organization:
- 8K x 8
- Memory Interface:
- SPI
- Clock Frequency:
- 10 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25LC640AT-E/ST FAQ
1.How can I place an order for 25LC640AT-E/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640AT-E/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 25LC640AT-E/ST reliable?
The price and inventory of 25LC640AT-E/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC640AT-E/ST is usually 5 days.
3.What payment methods are accepted for 25LC640AT-E/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640AT-E/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640AT-E/ST?
25LC640AT-E/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640AT-E/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 25LC640AT-E/ST?
For technical support, including 25LC640AT-E/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640AT-E/ST requirements.
6.How does Aetrix verify that 25LC640AT-E/ST is sourced from the original manufacturer or authorized distributors?
All 25LC640AT-E/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 25LC640AT-E/ST meets industry standards.
7.What is the process for return or replacement of 25LC640AT-E/ST?
All 25LC640AT-E/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640AT-E/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 25LC640AT-E/ST part is unused and in its original packaging.
Return procedure for 25LC640AT-E/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25LC640AT-E/ST Tags
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