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Microchip Technology 25AA040T/SN
- Part No.:
- 25AA040T/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25AA040T/SN.pdf
- Description:
- IC EEPROM 4KBIT SPI 1MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,450
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Product details
Overview
25AA040T/SN from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI-compatible serial EEPROM designed for nonvolatile data storage in low-power embedded systems. It operates from 1.8 V to 5.5 V, supports up to 1 MHz clock frequency, features 16-byte page write capability, and delivers 1 million endurance cycles with >200 years data retention. It is commonly used for configuration storage in industrial controllers and sensor calibration data logging.
For engineers reviewing the 25AA040T/SN datasheet, 25AA040T/SN pinout, 25AA040T/SN application, or 25AA040T/SN equivalent, key selection considerations include its 1.8 V minimum supply voltage, hardware write-protection via WP pin, HOLD functionality for interrupt-safe SPI pauses, and SOIC-8 (SN) package compatibility with space-constrained PCB layouts.
Technical Context
The 25AA040T/SN implements a standard SPI Mode 0,0 interface with separate SI (data in) and SO (data out) lines, requiring CS, SCK, SI, SO, WP, HOLD, VCC, and VSS connections. 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 status and block protection control.
Write operations require explicit WREN instruction before WRITE, followed by CS high to trigger self-timed internal write cycle (≤5 ms). Block protection is configurable via WRSR to lock none, upper 1/4 (0180h–01FFh), upper 1/2 (0100h–01FFh), or full array (0000h–01FFh), with hardware WP pin overriding software protection when asserted low.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 4 Kbit (512 × 8) - sufficient for firmware flags, calibration coefficients, or device ID storage in compact systems |
| Supply voltage | 1.8 V to 5.5 V - enables direct interfacing with 1.8 V, 3.3 V, and 5 V microcontrollers without level shifting |
| Max clock frequency | 1 MHz at VCC ≥ 4.5 V - supports fast configuration reads while maintaining timing margin in noisy environments |
| Page size | 16 bytes - limits burst writes to aligned pages; crossing page boundaries requires multiple write cycles |
| Write endurance | 1 million cycles - suitable for applications with frequent parameter updates, such as energy meter tariff tables |
| Data retention | >200 years at +25°C - ensures long-term reliability in unattended infrastructure equipment |
| Standby current | 500 nA typical - critical for battery-powered IoT nodes where quiescent power dominates lifetime budget |
Pinout & Package
25AA040T/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 notch or dot; orientation follows standard SOIC convention with pin 1 at top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select input | Active-low enable: drives device into active mode; high state places SO in high-Z for bus sharing |
| SO (Pin 2) | Serial Output | Tri-state output delivering read data on SCK falling edge; high-Z when CS high or HOLD low |
| WP (Pin 3) | Write-Protect input | Hardware lock: low disables all writes to memory and STATUS register regardless of WREN state |
| VSS (Pin 4) | Ground reference | Return path for all I/O and core logic; must be low-impedance connection to minimize noise coupling |
| SI (Pin 5) | Serial Input | Accepts instructions, addresses, and write data on SCK rising edge; latched synchronously |
| SCK (Pin 6) | Serial Clock input | Master-generated clock; rising edge latches SI, falling edge updates SO; max 1 MHz at full VCC range |
| HOLD (Pin 7) | Hold input | Pauses ongoing SPI transfer without resetting sequence; requires SCK low before assertion to avoid metastability |
| VCC (Pin 8) | Supply voltage | Core and I/O power rail; decoupling capacitor (0.1 μF) required within 10 mm of pin for stable operation |
Key Features
| Feature | Design Value |
|---|---|
| Low-voltage operation | 1.8 V minimum VCC enables integration with ultra-low-power MCUs (e.g., PIC16LF1xxx) without external regulators |
| Hardware write protection | WP pin provides fail-safe, always-active lock independent of firmware state-critical for safety-critical configuration registers |
| HOLD functionality | Allows host MCU to service higher-priority interrupts mid-transfer without losing SPI context or reinitializing communication |
| Configurable block protection | BP0/BP1 bits in STATUS register let designers partition memory into protected/unprotected zones for secure boot + user data separation |
| Self-timed write cycle | Internal timing eliminates need for host to manage erase/write delays; WIP bit allows polling instead of fixed wait states |
Applications
| Industrial Sensor Node | Medical Device Calibration |
|---|---|
|
Use Scenario: Storing temperature-compensated offset/gain coefficients across sensor operating range in battery-powered field transmitters. IC Role / Device Role / Timing Role: Nonvolatile configuration storage accessed during power-up and periodic recalibration routines via SPI. Use Value: 1.8 V operation matches sensor node's low-power MCU supply; 500 nA standby current extends battery life beyond 10 years. |
Use Scenario: Retaining factory-calibrated ADC reference points and patient-specific therapy parameters in portable infusion pumps. IC Role / Device Role / Timing Role: Secure, tamper-resistant data vault with hardware WP pin preventing runtime corruption during firmware updates. Use Value: Block protection (BP0/BP1) isolates immutable calibration data from modifiable therapy settings, meeting IEC 62304 Class B requirements. |
| Smart Energy Meter | Automotive Body Control Module |
|
Use Scenario: Logging time-of-use tariff schedules, billing cycle counters, and tamper-event timestamps in DIN-rail mounted meters. IC Role / Device Role / Timing Role: High-reliability data logger interfaced to metering SoC via dedicated SPI bus with HOLD support for real-time interrupt handling. Use Value: 1M endurance cycles withstand daily tariff updates over 27+ years; >200-year data retention ensures archival integrity across product lifecycle. |
Use Scenario: Storing seat position memory, mirror presets, and lighting profiles in 12 V automotive systems with wide-input DC-DC regulation. IC Role / Device Role / Timing Role: Configuration EEPROM co-located with BCM microcontroller, powered from regulated 3.3 V rail with WP tied to system security controller. Use Value: 1.8–5.5 V VCC range accommodates brown-out conditions during cold-crank; SOIC-8 footprint fits tight under-hood layout constraints. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA040A-I/SN | Enhanced revision with improved ESD rating (>6 kV HBM) and updated AC timing specs; same pinout and command set | Preferred for new designs per Microchip notice; identical use cases but higher robustness in ESD-prone environments | Select 25AA040A-I/SN for production builds requiring long-term availability and enhanced latch-up immunity |
| AT25040B-MAU-1.8 | 4 Kbit SPI EEPROM from Microchip (ex-Atmel); 1.8 V min, 20 MHz max clock, 1 M endurance, SOIC-8 package | Higher speed (20 MHz vs. 1 MHz) enables faster bulk reads; different instruction set and STATUS register layout | Choose AT25040B-MAU-1.8 only if host firmware can accommodate Atmel-specific opcodes and timing margins |
Compared with 25AA040T/SN, the 25AA040A-I/SN offers verified longevity and stronger ESD resilience without design changes, while the AT25040B-MAU-1.8 demands firmware adaptation for its faster interface and distinct protection model.
Availability
25AA040T/SN is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, and smart energy metering applications requiring stable component supply across extended product lifecycles.
Supply support for 25AA040T/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 devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25AA040T/SN belongs to Microchip's legacy SPI Serial EEPROM product line, engineered for cost-sensitive, low-power embedded systems requiring reliable nonvolatile storage with minimal board area and BOM count.
FAQ
What is the minimum supply voltage required for reliable operation of the 25AA040T/SN?
The 25AA040T/SN operates reliably down to 1.8 V across the full industrial temperature range (−40°C to +85°C). Below this threshold, read/write timing margins degrade and the write-enable latch may not set correctly. The 25AA040T/SN datasheet specifies guaranteed functionality only within the 1.8 V–5.5 V range, making it compatible with modern ultra-low-power microcontrollers without external level-shifting circuitry.
Does the 25AA040T/SN support page write operations, and what is the maximum page size?
Yes, the 25AA040T/SN supports page write operations with a fixed page size of 16 bytes. Up to 16 consecutive bytes within the same page boundary (e.g., addresses 0x00–0x0F) can be written in a single WRITE instruction sequence. Attempting to cross a page boundary during a page write will cause the internal address pointer to wrap, overwriting earlier bytes in the page-this behavior is documented in the 25AA040T/SN datasheet Section 3.3.
How does the HOLD pin function during an active SPI transaction on the 25AA040T/SN?
The HOLD pin on the 25AA040T/SN suspends ongoing SPI communication without resetting the internal state. When pulled low while SCK is low, SI, SO, and SCK inputs are ignored, and SO enters high-impedance. The 25AA040T/SN retains its position in the instruction/address/data sequence and resumes exactly where it left off when HOLD is returned high with SCK still low-enabling deterministic interrupt handling in real-time systems.
Can the 25AA040T/SN be used in automotive applications requiring −40°C to +125°C operation?
No, the 25AA040T/SN is rated only for the industrial temperature range (−40°C to +85°C). For automotive-grade operation up to +125°C, Microchip specifies the 25C040 variant (4.5 V–5.5 V supply) or the newer 25AA040A-IMNY variant qualified to AEC-Q100 Grade 3. Using the 25AA040T/SN outside its specified temperature range risks timing violations, increased write failure rate, and premature data retention loss.
What happens to the write enable latch after a successful write operation completes on the 25AA040T/SN?
After a successful write operation-whether byte, page, or STATUS register-the write enable latch (WEL) in the 25AA040T/SN is automatically reset to '0'. This prevents unintended subsequent writes unless WREN is explicitly reissued. The WEL bit remains cleared until the next WREN command is executed or until power-on reset, WRDI instruction, or WP pin assertion forces a reset-ensuring robust default protection against accidental writes.
25AA040T/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:
- Obsolete
- Programmable:
- Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 4Kbit
- Memory Organization:
- 512 x 8
- Memory Interface:
- SPI
- Clock Frequency:
- 1 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 1.8V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
25AA040T/SN FAQ
1.How can I place an order for 25AA040T/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA040T/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 25AA040T/SN reliable?
The price and inventory of 25AA040T/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA040T/SN is usually 5 days.
3.What payment methods are accepted for 25AA040T/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA040T/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA040T/SN?
25AA040T/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA040T/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 25AA040T/SN?
For technical support, including 25AA040T/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA040T/SN requirements.
6.How does Aetrix verify that 25AA040T/SN is sourced from the original manufacturer or authorized distributors?
All 25AA040T/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 25AA040T/SN meets industry standards.
7.What is the process for return or replacement of 25AA040T/SN?
All 25AA040T/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25AA040T/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 25AA040T/SN part is unused and in its original packaging.
Return procedure for 25AA040T/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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