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Microchip Technology 25LC640/S
- Part No.:
- 25LC640/S
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- Die
- Datasheet:
-
25LC640/S.pdf
- Description:
- IC EEPROM 64KBIT SPI 2MHZ DIE
- Quantity:
- Payment:
- Shipping:
Inventory:2,822
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Product details
Overview
25LC640/S from Microchip Technology Inc. is a 64 Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page write capability, and industrial temperature range (–40°C to +85°C). It operates at up to 2 MHz clock frequency with 2.5–5.5 V supply, features hardware write protection via WP pin and STATUS register, and targets nonvolatile data storage in microcontroller-based embedded systems.
For engineers reviewing the 25LC640/S datasheet, 25LC640/S pinout, 25LC640/S application, or 25LC640/S equivalent, this page delivers verified electrical specs, SPI timing constraints, block protection behavior, HOLD/CS interaction logic, and real-world use context for reliable integration into power-constrained, long-life industrial control and sensor node designs.
Technical Context
The 25LC640/S implements a standard SPI Mode 0,0 interface with separate SI (data-in) and SO (data-out) lines, requiring CS assertion, SCK synchronization, and optional HOLD suspension. Its internal architecture includes an 8-bit instruction register, auto-incrementing address pointer for sequential reads, and a nonvolatile STATUS register controlling BP0/BP1 block protection and WPEN hardware enable.
Write operations require explicit WREN instruction before WRITE or WRSR commands; internal self-timed write cycles complete in ≤5 ms with automatic WEL reset upon completion. The device supports four protection levels (none, upper 1/4, upper 1/2, or full array), enforced by combinational logic between WP pin state and STATUS register bits - not software-only masking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit), enabling storage of firmware parameters, calibration data, or event logs in compact MCU systems |
| Interface | SPI-compatible serial bus (Mode 0,0), eliminating parallel bus routing and reducing MCU pin count |
| Max Clock Frequency | 2 MHz at VCC = 2.5–5.5 V, supporting fast configuration loading without CPU overhead |
| Page Write Size | 32 bytes per page, constraining burst writes to aligned boundaries but minimizing write cycle overhead |
| Write Cycle Time | ≤5 ms max, defining minimum delay before polling WIP bit or initiating next operation |
| Data Retention | >200 years, ensuring long-term reliability in unattended or maintenance-free deployments |
| Endurance | 1 million erase/write cycles, supporting frequent logging or counter updates over product lifetime |
Pinout & Package
25LC640/S is supplied in 8-pin SOIC package (SN suffix), with 3.9 mm × 4.9 mm body, 1.27 mm pitch, and JEDEC MS-012AC compliant footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable: drives device into active mode; high-Z SO when deasserted enables multi-device SPI bus sharing |
| SO | Serial Data Output | Tri-state output updated on SCK falling edge; high-impedance when CS high or HOLD low |
| WP | Write-Protect Input | Hardware lock: disables STATUS register writes when WPEN=1 and WP=low; no effect if WPEN=0 |
| VSS | Ground Reference | Primary return path for all I/O and core logic; must be low-impedance to minimize noise coupling during read/write transitions |
| SI | Serial Data Input | Latches instruction/address/data on SCK rising edge; requires setup/hold timing compliance per AC table |
| SCK | Serial Clock Input | Master-generated clock synchronizing all SPI transactions; rise/fall times ≤2 μs required for timing margin |
| HOLD | Communication Suspend | Pauses ongoing SPI sequence without resetting state; must be asserted only when SCK is low |
| VCC | Supply Voltage | 2.5–5.5 V operating range; powers internal HV generator for EEPROM programming and logic circuits |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Selectable protection of none, upper 1/4 (1800h–1FFFh), upper 1/2 (1000h–1FFFh), or full array (0000h–1FFFh) via BP0/BP1 bits |
| Power-On Data Protection | Automatic WEL reset and STATUS register initialization prevent accidental writes after power-up or brownout |
| Low-Power Operation | 500 nA standby current and 500 μA read current enable battery-powered or energy-harvesting applications |
| HOLD Functionality | Enables host MCU to service higher-priority interrupts mid-transaction without losing SPI state or retransmitting commands |
| ESD Robustness | 4 kV HBM rating on all pins ensures resilience against handling and board-level ESD events in industrial environments |
Applications
| Industrial Sensor Node | Medical Device Calibration Storage |
|---|---|
Use Scenario: Storing temperature-compensation coefficients and sensor offset values in a wireless environmental monitor deployed for 10+ years. IC Role / Device Role / Timing Role: Nonvolatile parameter store accessed via SPI during boot and periodic recalibration; retains data across power cycles and thermal stress. Use Value: Eliminates need for external backup batteries or supercapacitors while guaranteeing >200-year data retention under field conditions. |
Use Scenario: Holding factory-calibrated ADC gain/offset values and user-adjusted therapy thresholds in a portable infusion pump. IC Role / Device Role / Timing Role: Secure configuration memory with hardware write-protection enabled (BP1/BP0=11) to prevent runtime corruption of safety-critical settings. Use Value: Meets IEC 62304 Class B software requirements by preventing unauthorized modification of calibrated parameters during operation. |
| Automotive Body Control Module | Smart Energy Meter Firmware Log |
Use Scenario: Recording door lock actuation history and seat position presets in a vehicle BCM operating across –40°C to +85°C. IC Role / Device Role / Timing Role: SPI EEPROM interfaced directly to 8-bit MCU; withstands automotive thermal cycling and vibration without data loss. Use Value: Supports AEC-Q100 stress testing with 1M endurance cycles and 125°C-rated variants available for extended temp versions. |
Use Scenario: Logging tamper events, voltage sags, and firmware update timestamps in a utility-grade electricity meter with 15-year service life. IC Role / Device Role / Timing Role: High-reliability data logger using page-write optimization to minimize wear on frequently updated event counters. Use Value: Enables deterministic 5 ms write latency and guaranteed 1M-cycle endurance for daily logging without wear leveling firmware. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SPI EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA640-I/SN | 1.8–5.5 V VCC range; 1 MHz max clock; compatible pinout and instruction set | Better suited for ultra-low-voltage systems (e.g., coin-cell powered devices) where 2.5 V minimum is not achievable | Select 25AA640-I/SN when operating below 2.5 V or requiring wider voltage margin; otherwise 25LC640/S offers higher speed |
| 25LC640A-I/SN | Enhanced revision with improved ESD (6 kV HBM), tighter AC timing, and updated qualification per AEC-Q100 Rev G | Required for new automotive designs targeting ASIL-B compliance; not drop-in due to revised DC/AC specs | Choose 25LC640A-I/SN for new production where long-term supply continuity and enhanced robustness are mandatory |
Compared with 25LC640/S, 25AA640-I/SN trades speed for lower-voltage operation, while 25LC640A-I/SN provides measurable reliability upgrades but requires design validation - neither is pin-compatible without checking layout tolerances for revised AC parameters.
Availability
25LC640/S is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, automotive body electronics, and smart metering applications requiring stable component supply and long-term data integrity.
Supply support for 25LC640/S 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, with global manufacturing and support infrastructure.
The 25LC640/S belongs to Microchip's legacy SPI Serial EEPROM product line, designed specifically for cost-sensitive, low-power embedded systems needing reliable, byte-addressable nonvolatile storage without complex controller overhead.
FAQ
What is the maximum clock frequency supported by the 25LC640/S?
The 25LC640/S supports up to 2 MHz clock frequency when operated within its specified VCC range of 2.5–5.5 V and industrial temperature range (–40°C to +85°C). At VCC = 4.5–5.5 V, it can run at 3 MHz, but this is limited to ambient temperatures ≤85°C per the datasheet AC characteristics table. Exceeding these limits risks timing violations or data corruption.
How does the HOLD pin function during an active SPI transaction on the 25LC640/S?
The HOLD pin on the 25LC640/S suspends ongoing SPI communication without resetting the internal state. When pulled low while SCK is low, SI/SO/SCK enter high-impedance states and input transitions are ignored except for CS. To resume, HOLD must be raised while SCK remains low. This allows the host MCU to service urgent interrupts and continue exactly where the transaction paused - critical for real-time system responsiveness.
Can the 25LC640/S be used in automotive applications requiring extended temperature range?
The standard 25LC640/S is rated for industrial temperature range (–40°C to +85°C). For automotive applications up to +125°C, Microchip specifies the 25LC640 variant with E-temp grade (–40°C to +125°C), which shares identical pinout and instruction set but requires verification of AC timing at elevated temperature. The /S suffix denotes SOIC packaging, not temperature grade - always confirm the full part number includes 'E' for automotive use.
What happens to the write enable latch after a successful write operation on the 25LC640/S?
After a successful WRITE, WRSR, or WRDI instruction execution, the write enable latch (WEL) in the 25LC640/S is automatically reset to '0'. This prevents unintended subsequent writes unless WREN is explicitly reissued. Power-up also resets WEL, and the latch remains inactive until the host sends the 0000 0110 (WREN) command and brings CS high to commit the enable - a key safety mechanism against spurious writes.
How is block protection configured on the 25LC640/S, and what addresses does each setting protect?
Block protection on the 25LC640/S is controlled by BP1/BP0 bits in the STATUS register, written via WRSR instruction. BP1=0/BP0=0 protects none; BP1=0/BP0=1 protects upper 1/4 (1800h–1FFFh); BP1=1/BP0=0 protects upper 1/2 (1000h–1FFFh); BP1=1/BP0=1 protects full array (0000h–1FFFh). Protection is enforced only when WP=low and WPEN=1 - otherwise, all blocks remain writable.
25LC640/S Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- Die
- Packaging:
- Tray
- 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:
- 2 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- Die
25LC640/S FAQ
1.How can I place an order for 25LC640/S through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640/S 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 25LC640/S reliable?
The price and inventory of 25LC640/S are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC640/S is usually 5 days.
3.What payment methods are accepted for 25LC640/S?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640/S transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640/S?
25LC640/S orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640/S 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 25LC640/S?
For technical support, including 25LC640/S datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640/S requirements.
6.How does Aetrix verify that 25LC640/S is sourced from the original manufacturer or authorized distributors?
All 25LC640/S 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 25LC640/S meets industry standards.
7.What is the process for return or replacement of 25LC640/S?
All 25LC640/S units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640/S, 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 25LC640/S part is unused and in its original packaging.
Return procedure for 25LC640/S:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25LC640/S Tags
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M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
Microchip Technology
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AT21CS01-STUM10-T
Microchip Technology
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AT24C02C-SSHM-T
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24LC01BT-I/OT
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M24C02-FMC6TG
STMicroelectronics
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AT24CS02-SSHM-T
Microchip Technology
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93LC46BT-I/OT
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AT24C04C-SSHM-T
Microchip Technology
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24LC01BT-I/SN
Microchip Technology
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24AA02UIDT-I/OT
Microchip Technology
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AT24C08C-STUM-T
Microchip Technology
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