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Microchip Technology 25AA640A-E/SN
- Part No.:
- 25AA640A-E/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25AA640A-E/SN.pdf
- Description:
- IC EEPROM 64KBIT SPI 10MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,723
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Product details
Overview
25AA640A-E/SN from Microchip Technology Inc. is a 64-Kbit SPI serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and 1.8V–5.5V supply range. It supports up to 10 MHz clock (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 - used in industrial control firmware storage and sensor calibration data logging.
For engineers reviewing the 25AA640A-E/SN datasheet, 25AA640A-E/SN pinout, 25AA640A-E/SN application, or 25AA640A-E/SN equivalent, key selection criteria include voltage compatibility (1.8V–5.5V), SPI Mode 0/1 support, HOLD functionality for interrupt-safe operation, and block-level write protection granularity (none/1/4/1/2/all).
Technical Context
The 25AA640A-E/SN implements a standard SPI interface with separate SI (data-in) and SO (data-out) lines, CS-controlled selection, and SCK-synchronized communication. Its internal architecture includes a page latch buffer, HV generator for EEPROM programming, and status register with WIP, WEL, BP0/BP1, and WPEN bits.
It supports sequential read, byte/page write, and HOLD suspension of ongoing transfers without sequence reset. Write operations require explicit WREN instruction and CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms), with automatic WEL reset upon completion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit array) - provides sufficient nonvolatile storage for configuration tables, calibration coefficients, or boot parameters in resource-constrained microcontroller systems. |
| Interface | SPI-compatible serial bus (Mode 0,0 and Mode 1,1) - enables direct connection to MCU SPI peripherals without protocol translation or additional logic. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5V - enables fast firmware update or log writes; drops to 5 MHz at 2.5V–4.5V and 3 MHz below 2.5V for robust low-voltage operation. |
| Page Size | 32 bytes - defines maximum contiguous write length per command; crossing physical page boundaries causes wraparound, requiring software boundary management. |
| Write Endurance | 1,000,000 erase/write cycles - supports frequent field-updatable parameters (e.g., energy metering logs, HVAC runtime counters) over product lifetime. |
| Data Retention | >200 years at +25°C - ensures long-term integrity of stored calibration data, device IDs, or security keys without refresh. |
| Operating Temp | −40°C to +125°C (Extended grade) - qualified for under-hood automotive, industrial motor drives, and outdoor IoT edge nodes. |
Pinout & Package
25AA640A-E/SN is packaged in an 8-lead narrow SOIC (SN) with 150-mil body width and standard 1.27 mm pitch. Pin 1 is marked by a beveled corner or notch; package meets RoHS and AEC-Q100 Grade 1 requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low enable: selects device for SPI communication; high state forces standby mode and tri-states SO for bus sharing. |
| SO (Pin 2) | Serial Output | Data-out line: outputs memory contents on falling edge of SCK during READ; enters high-impedance when CS is high or HOLD is asserted. |
| WP (Pin 3) | Write-Protect Input | Hardware lock: when WPEN bit = 1 and WP = low, disables writes to STATUS register nonvolatile bits; all other functions remain active. |
| VSS (Pin 4) | Ground | Reference return path for all I/O and core circuitry; must be low-impedance to ensure noise immunity during high-speed SPI transfers. |
| SI (Pin 5) | Serial Input | Data-in line: accepts instructions, addresses, and write data on rising edge of SCK; latched only when CS is low and HOLD is high. |
| SCK (Pin 6) | Serial Clock | Master-generated clock: synchronizes all data transfers; rising edge clocks SI, falling edge updates SO; timing constraints vary with VCC. |
| HOLD (Pin 7) | Hold Input | Transfer pause: suspends ongoing SPI sequence when pulled low (with SCK low); resumes automatically when released, preserving address pointer and state. |
| VCC (Pin 8) | Supply Voltage | Power input: operates from 1.8V to 5.5V; supports mixed-voltage systems and battery-backed operation down to 1.8V with reduced clock rate. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed write cycle | ≤5 ms internal erase/write - eliminates need for external timing control or polling delay; WIP bit allows precise host synchronization. |
| Block write protection | Configurable via BP0/BP1 bits to protect none, upper 1/4 (1800h–1FFFh), upper 1/2 (1000h–1FFFh), or entire array - prevents accidental overwrite of critical firmware or calibration zones. |
| HOLD function | Pauses SPI transfer mid-sequence without resetting address pointer - enables MCU to service time-critical interrupts (e.g., motor fault, safety shutdown) and resume transparently. |
| Power-on write protection | WEL reset and WPEN default state prevent unintended writes at power-up - eliminates need for external POR circuitry or firmware initialization guards. |
| Low-power operation | 1 µA standby current at 5.5V/85°C - suitable for always-on battery-powered devices such as smart meters and wireless sensors. |
Applications
| Industrial PLC Configuration Storage | Automotive ECU Calibration Data |
|---|---|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and user-defined logic configurations in programmable logic controllers that undergo periodic field updates. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via SPI during boot and runtime reconfiguration; HOLD enables safe parameter reload during motion control interrupts. Use Value: 1M endurance supports daily parameter adjustments over 10+ years; 125°C rating ensures reliability in cabinet-mounted PLCs near heat-generating drives. |
Use Scenario: Retaining sensor offset corrections, fuel trim values, and adaptive learning data across ignition cycles in engine control units. IC Role / Device Role / Timing Role: AEC-Q100 qualified EEPROM interfacing directly with MCU's SPI port; WP pin hard-locks calibration region during normal operation. Use Value: >200-year data retention preserves factory calibrations over vehicle lifetime; 1.8V operation enables backup power from supercapacitors during cold cranking. |
| Medical Device Usage Logs | Smart Energy Meter Firmware Patch Storage |
Use Scenario: Recording sterilization cycles, usage hours, and diagnostic event timestamps in portable infusion pumps and ventilators requiring regulatory audit trails. IC Role / Device Role / Timing Role: Tamper-resistant log storage with write-protection enabled after each session; sequential read supports rapid report generation. Use Value: ESD protection >4 kV prevents corruption from handling discharge; RoHS compliance meets IEC 60601-1 medical safety standards. |
Use Scenario: Holding delta patches for firmware upgrades in utility-grade electricity meters deployed in remote substations with infrequent maintenance windows. IC Role / Device Role / Timing Role: Secure patch repository accessed only during validated OTA update sequences; block protection isolates patch area from main firmware. Use Value: 32-byte page writes minimize flash wear on host MCU; 10 MHz interface accelerates patch validation and installation in <500 ms. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC640A-E/SN | Requires minimum 2.5V VCC; identical pinout, timing, and feature set otherwise. | Not suitable for 1.8V systems (e.g., ultra-low-power IoT sensors); same industrial/automotive use cases above 2.5V. | Select 25LC640A-E/SN only if system VCC never drops below 2.5V; otherwise 25AA640A-E/SN provides broader voltage margin. |
| AT25DF641A-SHN-T | Quad SPI interface, 3V-only supply (2.7–3.6V), 64 Mbit density, no HOLD pin. | Higher throughput for large firmware images but incompatible with standard SPI-only hosts and 1.8V/5V systems. | Choose AT25DF641A-SHN-T only when quad I/O bandwidth is required and voltage rails match; not a drop-in replacement. |
Compared with 25LC640A-E/SN, the 25AA640A-E/SN extends operational voltage down to 1.8V for battery-backed designs, while AT25DF641A-SHN-T trades pin compatibility and voltage flexibility for higher density and faster quad-mode reads - making it unsuitable for legacy SPI-only or wide-VCC applications.
Availability
25AA640A-E/SN is available at Aetrix Electronics and suitable for industrial control systems, automotive ECUs, medical instrumentation, and smart metering applications requiring stable component supply, long-term lifecycle support, and AEC-Q100 qualification.
Supply support for 25AA640A-E/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, FPGA, and memory solutions, serving industrial, automotive, communications, and consumer markets with integrated silicon and development tools.
The 25AA640A belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile data storage in space- and cost-constrained embedded systems requiring extended temperature operation and high endurance.
FAQ
What is the operating voltage range of the 25AA640A-E/SN?
The 25AA640A-E/SN operates from 1.8V to 5.5V, enabling use in both low-voltage battery-powered devices and standard 3.3V/5V industrial systems. Its AC characteristics scale with VCC: max clock is 10 MHz at ≥4.5V, 5 MHz at 2.5–4.5V, and 3 MHz at 1.8–2.5V. This wide range eliminates need for level shifters in mixed-rail designs.
How does the HOLD function work on the 25AA640A-E/SN?
The HOLD pin on the 25AA640A-E/SN pauses an active SPI transaction without resetting the address pointer or internal state. To invoke HOLD, the pin must be pulled low while SCK is low; SO, SI, and SCK enter high-impedance, ignoring further transitions. Resuming requires bringing HOLD high while SCK remains low. This allows MCUs to service urgent interrupts and resume EEPROM access seamlessly.
Can the 25AA640A-E/SN be used in automotive applications?
Yes - the 25AA640A-E/SN is AEC-Q100 qualified for Extended temperature range (−40°C to +125°C) and is commonly deployed in automotive ECUs for storing calibration data, adaptive learning values, and fault logs. Its 1 million endurance and >200-year data retention meet stringent automotive reliability requirements, and the WP pin provides hardware-level protection against unintended writes during vehicle operation.
What is the page size and why does it matter for writing to the 25AA640A-E/SN?
The 25AA640A-E/SN has a 32-byte page size, meaning up to 32 contiguous bytes can be written in a single Page Write command. Crossing a 32-byte boundary causes data to wrap within the current page instead of advancing to the next, risking overwrite of valid data. Software must align write addresses and limit length to avoid boundary violations - critical for robust firmware update or logging routines.
How is write protection implemented on the 25AA640A-E/SN?
Write protection on the 25AA640A-E/SN uses dual mechanisms: (1) Block Protection bits (BP0/BP1) in the STATUS register to lock 0%, 25%, 50%, or 100% of the memory array; and (2) Hardware WP pin, enabled only when WPEN bit = 1 and WP = low, which blocks writes to nonvolatile STATUS bits. Both are independent and can be combined for layered security in safety-critical applications.
25AA640A-E/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- 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:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
25AA640A-E/SN FAQ
1.How can I place an order for 25AA640A-E/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA640A-E/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 25AA640A-E/SN reliable?
The price and inventory of 25AA640A-E/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA640A-E/SN is usually 5 days.
3.What payment methods are accepted for 25AA640A-E/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA640A-E/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA640A-E/SN?
25AA640A-E/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA640A-E/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 25AA640A-E/SN?
For technical support, including 25AA640A-E/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA640A-E/SN requirements.
6.How does Aetrix verify that 25AA640A-E/SN is sourced from the original manufacturer or authorized distributors?
All 25AA640A-E/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 25AA640A-E/SN meets industry standards.
7.What is the process for return or replacement of 25AA640A-E/SN?
All 25AA640A-E/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25AA640A-E/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 25AA640A-E/SN part is unused and in its original packaging.
Return procedure for 25AA640A-E/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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