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Microchip Technology 25LC040T/SN
- Part No.:
- 25LC040T/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25LC040T/SN.pdf
- Description:
- IC EEPROM 4KBIT SPI 2MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,300
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Product details
Overview
25LC040T/SN from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI-compatible serial EEPROM designed for nonvolatile data storage in embedded control and sensor systems. It operates from 2.5V to 5.5V, supports up to 2 MHz clock frequency, features 16-byte page write capability, and delivers 1 million endurance cycles with >200 years data retention. It is commonly used in industrial controllers for parameter storage and calibration data backup.
For engineers reviewing the 25LC040T/SN datasheet, 25LC040T/SN pinout, 25LC040T/SN application, or 25LC040T/SN equivalent, key selection considerations include VCC range compatibility (2.5–5.5V), SOIC-8 package footprint, HOLD/CS/WP hardware control logic, and block-level write protection configuration via STATUS register.
Technical Context
The 25LC040T/SN implements a standard SPI Mode 0,0 interface with separate SI (data in) and SO (data out) lines, requiring CS activation and SCK synchronization. Its internal architecture includes an 8-bit instruction register, automatic address incrementing during sequential reads, and a status register with WIP, WEL, BP0, and BP1 bits for real-time write monitoring and 1/4–full array protection.
Write operations require explicit WREN instruction followed by CS high assertion to initiate self-timed internal erase/write cycles (≤5 ms). Hardware controls-HOLD for bus suspension and WP for immediate write inhibition-operate independently of firmware state and remain active across power transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 4 Kbit (512 × 8-bit array), sufficient for firmware configuration tables or sensor calibration coefficients in space-constrained designs. |
| Interface | SPI Mode 0,0 (CPOL=0, CPHA=0) with dedicated SI/SO lines - enables direct connection to MCU SPI peripherals without level-shifting or protocol translation. |
| Max clock frequency | 2 MHz at VCC ≥ 2.5V - supports fast read/write bursts while maintaining timing margins in noise-prone industrial environments. |
| Page size | 16 bytes - constrains write buffer design to align writes within page boundaries to avoid rollover corruption during multi-byte updates. |
| Write endurance | 1 million erase/write cycles - ensures reliable operation over 10+ years in daily logging or parameter update applications. |
| Data retention | >200 years at +85°C - guarantees long-term integrity of stored calibration or security keys without refresh mechanisms. |
| Supply voltage | 2.5V to 5.5V - interoperable with both 3.3V and 5V microcontroller I/O domains without external regulators or level shifters. |
Pinout & Package
25LC040T/SN is supplied in an 8-pin SOIC (SN) package, 150 mil width, with JEDEC MS-012 compliance and Pb-free matte tin finish. Pin 1 is marked with a dot or bevel; pin numbering follows standard SOIC convention (counterclockwise from top-left corner).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select input | Active-low enable: drives device into standby when high; must go low before any SPI transaction; rising edge after write sequence triggers internal write cycle. |
| SO (Pin 2) | Serial Output | Tri-state open-drain output: data shifted out on SCK falling edge; enters high-Z when CS high or HOLD low - enables multi-device SPI bus sharing. |
| WP (Pin 3) | Write-Protect input | Hardware lock: disables all writes (array and STATUS register) when pulled low; overrides WREN state and persists across power cycles. |
| VSS (Pin 4) | Ground reference | Primary return path for all internal circuitry and I/O leakage currents; must be low-impedance and decoupled near VCC pin. |
| SI (Pin 5) | Serial Input | Data/command input: latches instruction, address, and write data on SCK rising edge; requires clean setup/hold timing per AC specs (e.g., TSU ≥ 30 ns at 2.5V). |
| SCK (Pin 6) | Serial Clock input | Synchronization source: defines SPI bit rate and sampling edges; rise/fall times ≤2 μs required to meet internal timing constraints. |
| HOLD (Pin 7) | Bus hold control | Pauses ongoing SPI transfer: must be asserted low while SCK is low; suspends SO/SI/SCK activity without resetting internal address pointer or command state. |
| VCC (Pin 8) | Supply voltage | Power input: accepts 2.5–5.5V; internal regulation supports stable EEPROM operation across wide input range; requires local 0.1 μF ceramic decoupling. |
Key Features
| Feature | Design Value |
|---|---|
| Block write protection | Selectable 0%, 25%, 50%, or 100% array protection via BP0/BP1 bits - prevents accidental overwrite of critical firmware parameters or calibration zones. |
| Hardware write-enable latch | WREN/WRDI instructions control volatile write permission - eliminates unintended writes during power transients or reset sequences. |
| Self-timed write cycle | Internal 5 ms max erase/write completion - removes need for software delay loops; STATUS register WIP bit enables precise polling-based completion detection. |
| Low-power operation | 500 nA standby current and 3 mA typical write current - extends battery life in portable instrumentation and remote sensor nodes. |
| HOLD pin functionality | Real-time SPI bus suspension without reinitialization - allows host MCU to service higher-priority interrupts mid-transaction and resume seamlessly. |
Applications
| Industrial PLC Configuration Storage | Smart Sensor Calibration Data Retention |
|---|---|
Use Scenario: Storing I/O mapping, scaling factors, and alarm thresholds in programmable logic controllers deployed in factory automation cabinets. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via SPI during boot and runtime parameter updates. Use Value: Enables field-upgradable settings without firmware reflashing; BP bits prevent corruption of safety-critical configuration blocks during maintenance. |
Use Scenario: Holding temperature-compensated offset/gain coefficients and sensor linearization tables in digital pressure or humidity sensors. IC Role / Device Role / Timing Role: Calibration data repository read once at startup and cached in RAM for real-time compensation. Use Value: Maintains measurement accuracy across product lifetime; 200-year retention eliminates recalibration requirements in sealed industrial enclosures. |
| Medical Device Usage Logs | Consumer Appliance Settings Backup |
Use Scenario: Recording sterilization cycles, error events, and usage counters in portable diagnostic equipment subject to regulatory audit trails. IC Role / Device Role / Timing Role: Tamper-resistant event logger with atomic write capability and hardware WP lock during idle periods. Use Value: Meets IEC 62304 data integrity requirements; 1M endurance supports >10 years of daily logging at 300 entries/day. |
Use Scenario: Preserving user preferences (e.g., cooking modes, display brightness) and energy consumption history in smart ovens and washing machines. IC Role / Device Role / Timing Role: Persistent settings store interfaced via MCU SPI with HOLD support for interrupt-driven UI responsiveness. Use Value: Survives frequent power cycling and brownout conditions; low 500 nA standby current minimizes standby battery drain. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA040T/SN | Wider VCC range (1.8–5.5V); supports 1 MHz max clock; identical pinout and instruction set. | Better suited for mixed-voltage systems or battery-powered devices operating below 2.5V. | Select when system VCC may dip below 2.5V or when lower power consumption at 1.8V is required. |
| 25LC040A/SN | Pin-compatible revision with enhanced ESD rating (>6 kV HBM), improved AC timing margins, and updated qualification per AEC-Q100 stress tests. | Preferred for new automotive or high-reliability industrial designs requiring extended lifecycle validation. | Choose for new designs where long-term supply continuity and automotive-grade robustness are mandatory. |
Compared with 25LC040T/SN, 25AA040T/SN extends voltage flexibility but reduces speed, while 25LC040A/SN maintains full compatibility with improved reliability - making the latter the recommended upgrade path for production ramp.
Availability
25LC040T/SN is available at Aetrix Electronics and suitable for industrial PLCs, smart sensors, medical loggers, and consumer appliance control systems requiring stable component supply and long-term obsolescence management.
Supply support for 25LC040T/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, with global manufacturing and support infrastructure.
The 25LC040T/SN belongs to Microchip's legacy SPI Serial EEPROM product line, engineered for cost-sensitive, space-constrained embedded systems requiring reliable nonvolatile storage with minimal external components.
FAQ
What is the maximum clock frequency supported by the 25LC040T/SN?
The 25LC040T/SN supports up to 2 MHz clock frequency when VCC is 2.5V or higher. At lower voltages (e.g., 1.8V), the maximum clock drops to 1 MHz - but since 25LC040T/SN is specified for 2.5–5.5V operation, 2 MHz is its guaranteed maximum. This enables efficient data transfers in real-time control loops without introducing SPI bottlenecks.
Does the 25LC040T/SN require external pull-up resistors on its SO or SI lines?
No, the 25LC040T/SN does not require external pull-ups on SO or SI. Its SO pin is internally driven and tri-stated when inactive, and SI is a CMOS input with negligible leakage. Pull-ups are only needed if bus contention occurs in multi-slave configurations - but proper CS decoding and signal integrity practices eliminate that need for 25LC040T/SN.
How does the HOLD pin function during an active write cycle in the 25LC040T/SN?
The HOLD pin has no effect on an ongoing internal write cycle in the 25LC040T/SN. Once CS rises after a write command, the device initiates self-timed programming independent of HOLD state. HOLD only pauses serial communication (read/write commands), not active erase/write operations already committed to internal execution.
Can the 25LC040T/SN be used interchangeably with the 25C040T/SN in a 5V system?
No - while both share the same SOIC-8 package and instruction set, the 25LC040T/SN is rated for 2.5–5.5V operation and the 25C040T/SN is specified only for 4.5–5.5V. Using 25LC040T/SN at 5V is fully compliant, but substituting 25C040T/SN in a 2.5V system will cause functional failure. Always verify VCC compatibility before substitution.
What happens to the write enable latch in the 25LC040T/SN after a successful write operation?
After a successful byte, page, or STATUS register write, the 25LC040T/SN automatically resets the write enable latch (WEL = 0). This means each subsequent write requires reissuing the WREN instruction - a safety feature preventing accidental overwrites due to residual latch state or noise-induced command corruption.
25LC040T/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:
- 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:
- 8-SOIC
25LC040T/SN FAQ
1.How can I place an order for 25LC040T/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC040T/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 25LC040T/SN reliable?
The price and inventory of 25LC040T/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC040T/SN is usually 5 days.
3.What payment methods are accepted for 25LC040T/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC040T/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC040T/SN?
25LC040T/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC040T/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 25LC040T/SN?
For technical support, including 25LC040T/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC040T/SN requirements.
6.How does Aetrix verify that 25LC040T/SN is sourced from the original manufacturer or authorized distributors?
All 25LC040T/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 25LC040T/SN meets industry standards.
7.What is the process for return or replacement of 25LC040T/SN?
All 25LC040T/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25LC040T/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 25LC040T/SN part is unused and in its original packaging.
Return procedure for 25LC040T/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25LC040T/SN Tags
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