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Microchip Technology 25LC640A-E/ST
- Part No.:
- 25LC640A-E/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25LC640A-E/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:503
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Product details
Overview
25LC640A-E/ST from Microchip Technology Inc. is a 64-Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and industrial-extended temperature support (–40°C to +125°C). It operates at up to 10 MHz clock frequency (at VCC ≥ 4.5V), features hardware write protection via WP pin and STATUS register, and delivers 1 million erase/write cycles with >200-year data retention - deployed in automotive body control modules for configuration storage.
For engineers reviewing the 25LC640A-E/ST datasheet, 25LC640A-E/ST pinout, 25LC640A-E/ST application, or 25LC640A-E/ST equivalent, key selection criteria include VCC range (2.5V–5.5V), HOLD/CS/SO/SI/SCK/WP/VSS/VCC 8-pin interface, page-write timing (≤5 ms), and AEC-Q100 qualification for extended-temperature automotive use.
Technical Context
The 25LC640A-E/ST implements an SPI Mode 0,0/Master-Slave interface with separate SI (data-in) and SO (data-out) lines, requiring CS low and HOLD high for active operation. Its internal architecture includes a 32-byte page latch, HV generator for EEPROM programming, and status register with WIP, WEL, BP0/BP1, and WPEN bits for granular block protection.
Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (TWC ≤ 5 ms); read operations support sequential addressing with automatic address roll-over at 1FFFh. HOLD pin suspends ongoing transfers without resetting the sequence, enabling interrupt servicing in real-time microcontroller systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit array), sufficient for firmware parameter tables or calibration data in ECUs. |
| Interface | SPI-compatible serial bus (Mode 0,0), compatible with PIC® and ARM Cortex-M microcontrollers without custom bit-banging. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5V; reduces to 5 MHz at 2.5V–4.5V, enabling power-aware clock scaling in battery systems. |
| Page Size | 32 bytes per page; enforces software boundary checks to prevent wrap-around during multi-byte writes. |
| Write Endurance | 1,000,000 erase/write cycles - supports daily reconfiguration over 27+ years in industrial logging applications. |
| Data Retention | >200 years at +85°C - ensures long-term reliability in sealed automotive modules without refresh cycles. |
| Supply Voltage | 2.5V to 5.5V operating range - interoperable with 3.3V logic and legacy 5V systems without level-shifting. |
Pinout & Package
25LC640A-E/ST is packaged in an 8-lead SOIC (SN) with 150-mil body width, RoHS-compliant matte tin finish, and standard JEDEC MS-012AC footprint (5.3mm × 4.4mm × 1.75mm).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable; forces SO into high-impedance when high, allowing shared SPI bus with multiple slaves. |
| SO | Serial Data Output | Tri-state output updated on SCK falling edge; requires external pull-up for open-drain compatibility. |
| WP | Write-Protect Pin | Hardware lock for STATUS register when WPEN=1; grounded to disable nonvolatile writes during field updates. |
| VSS | Ground Reference | Primary return path for all I/O and core circuitry; must be low-inductance connection in noise-sensitive environments. |
| SI | Serial Data Input | Latches instruction/address/data on SCK rising edge; tolerant of 1.8V–5.5V logic levels per DC specs. |
| SCK | Serial Clock Input | Synchronizes all transfers; rise/fall times ≤100 ns required for 10 MHz operation at 5.5V. |
| HOLD | Transfer Suspend Input | Pauses ongoing SPI sequence when pulled low during SCK low phase; resumes on next SCK low-to-high transition. |
| VCC | Supply Voltage | 2.5V–5.5V input; decoupling capacitor (0.1 µF ceramic) required within 5 mm of pin per layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Selectively locks 0%, 25%, 50%, or 100% of memory via BP0/BP1 bits - prevents accidental overwrite of critical boot parameters. |
| Power-on Write Protection | Automatic WEL reset at power-up and after every write completes - eliminates spurious writes during brown-out conditions. |
| HOLD Functionality | Enables deterministic pause/resume of SPI transfers without re-synchronizing clocks or addresses - essential for real-time interrupt latency control. |
| AEC-Q100 Qualification | Validated for automotive extended temperature (–40°C to +125°C) and HTOL stress - qualified for under-hood ECU deployment. |
| ESD Robustness | >4 kV HBM rating on all pins - withstands handling and board-level ESD events without latch-up or parametric shift. |
Applications
| Automotive Body Control Unit | Industrial PLC Configuration Storage |
|---|---|
Use Scenario: Storing seat/mirror position presets, door lock settings, and lighting profiles in vehicle BCMs across product lifecycles. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed via SPI during MCU boot and runtime parameter updates. Use Value: AEC-Q100 qualification and >200-year data retention ensure settings persist through 15+ year vehicle service life without backup power. | Use Scenario: Holding I/O mapping tables, PID tuning constants, and alarm thresholds in modular PLC backplanes. IC Role / Device Role / Timing Role: SPI-configurable memory mapped to controller's peripheral address space for dynamic parameter loading. Use Value: 1M endurance enables daily firmware updates and field calibration without wear-out concerns over 10+ years of operation. |
| Medical Infusion Pump Calibration | Smart Energy Meter Firmware Patching |
Use Scenario: Storing calibrated flow rate coefficients and safety-critical dose limits in Class II medical devices requiring FDA audit trails. IC Role / Device Role / Timing Role: Secure, write-protected memory partition accessed only during authorized calibration sessions. Use Value: Hardware WP pin + BP bits enforce dual-layer protection against unauthorized writes during maintenance procedures. | Use Scenario: Hosting field-upgradable firmware patches and tariff schedule tables in utility-grade electricity meters. IC Role / Device Role / Timing Role: SPI-bootloader target memory with 5 ms max write time enabling sub-second OTA updates. Use Value: 10 MHz interface speed and 32-byte page writes reduce update window duration, minimizing meter downtime during grid maintenance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT25DF041A-SSH-T | 4 Mbit density, quad SPI interface, no HOLD pin, 85°C max temp | Higher capacity but lacks HOLD and extended-temp support; not AEC-Q100 qualified | Choose only if >64 Kbit capacity and quad I/O bandwidth are required, and automotive qualification is unnecessary. |
| BR25H640FJ-WE2 | 64 Kbit, SPI interface, built-in voltage detector, –40°C to +125°C, same 8-pin SOP package | Includes reset-on-voltage-drop function; pinout identical but WP/HOLD roles differ per datasheet | Prefer when system-level brown-out recovery is needed; verify HOLD timing alignment before drop-in replacement. |
Compared with AT25DF041A-SSH-T and BR25H640FJ-WE2, the 25LC640A-E/ST uniquely combines AEC-Q100 qualification, HOLD functionality, and hardware write protection in a proven 8-pin SOIC footprint - making it optimal for safety-critical automotive and industrial control where deterministic suspend and tamper resistance are mandatory.
Availability
25LC640A-E/ST is available at Aetrix Electronics and suitable for automotive body electronics, industrial programmable logic controllers, and medical device calibration storage requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for 25LC640A-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 leading provider of microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25LC640A-E/ST belongs to Microchip's serial EEPROM product line, engineered specifically for reliable, low-power nonvolatile storage in automotive, industrial, and medical systems demanding extended temperature operation and robust data integrity.
FAQ
What is the maximum clock frequency supported by the 25LC640A-E/ST?
The 25LC640A-E/ST supports up to 10 MHz clock frequency when VCC is between 4.5V and 5.5V. At 2.5V ≤ VCC < 4.5V, the maximum clock drops to 5 MHz, and at 1.8V ≤ VCC < 2.5V (not applicable to 25LC640A-E/ST due to its 2.5V minimum VCC), it would be 3 MHz. This voltage-dependent frequency scaling ensures stable operation across diverse power domains while maintaining timing compliance.
Does the 25LC640A-E/ST require external components for basic SPI operation?
Yes - the 25LC640A-E/ST requires a 0.1 µF ceramic decoupling capacitor placed within 5 mm of the VCC and VSS pins. No pull-up resistors are mandatory for SO, but a 4.7 kΩ pull-up is recommended for noise immunity on long traces. The WP and HOLD pins may need pull-up/pull-down resistors depending on system-level protection and suspend logic requirements.
How does the HOLD function behave during an active write cycle in the 25LC640A-E/ST?
The HOLD function is disabled during an internal write cycle (TWC) in the 25LC640A-E/ST. Once a write is initiated (CS rising edge after valid sequence), the device ignores HOLD transitions until the write completes. This ensures write atomicity - preventing partial writes or corruption due to premature suspension. HOLD resumes normal operation only after TWC finishes and the device returns to standby or read-ready state.
Can the 25LC640A-E/ST be used in place of the 25AA640A in existing designs?
No - the 25LC640A-E/ST has a minimum VCC of 2.5V, whereas the 25AA640A supports down to 1.8V. Substituting 25LC640A-E/ST into a 1.8V system will cause functional failure. Additionally, the 25LC640A-E/ST is rated for extended temperature (–40°C to +125°C), while many 25AA640A variants are limited to industrial range (–40°C to +85°C), so thermal validation is required even if voltage matches.
What packaging and marking identify the 25LC640A-E/ST variant?
The 25LC640A-E/ST uses an 8-lead SOIC (SN) package with "E" temperature grade (–40°C to +125°C) and "ST" suffix indicating tape-and-reel packaging. Marking includes "5LCA" prefix followed by "E" and date code (e.g., "5LCAE2112" for week 12 of 2021), conforming to Microchip's standard SOIC top-side laser marking per DS20001830G-page 14.
25LC640A-E/ST Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- 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
25LC640A-E/ST FAQ
1.How can I place an order for 25LC640A-E/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640A-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 25LC640A-E/ST reliable?
The price and inventory of 25LC640A-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 25LC640A-E/ST is usually 5 days.
3.What payment methods are accepted for 25LC640A-E/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640A-E/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640A-E/ST?
25LC640A-E/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640A-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 25LC640A-E/ST?
For technical support, including 25LC640A-E/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640A-E/ST requirements.
6.How does Aetrix verify that 25LC640A-E/ST is sourced from the original manufacturer or authorized distributors?
All 25LC640A-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 25LC640A-E/ST meets industry standards.
7.What is the process for return or replacement of 25LC640A-E/ST?
All 25LC640A-E/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640A-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 25LC640A-E/ST part is unused and in its original packaging.
Return procedure for 25LC640A-E/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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