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Microchip Technology 25AA640X-I/ST
- Part No.:
- 25AA640X-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25AA640X-I/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 1MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,753
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Product details
Overview
25AA640X-I/ST from Microchip Technology Inc. is a 64 Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 1.8–5.5 V supply range, and industrial temperature rating (–40°C to +85°C), housed in an 8-lead TSSOP package with alternate pinout. It supports up to 1 MHz clock frequency, features 32-byte page write capability, and delivers ultra-low standby current (500 nA typical) for battery-backed systems.
For engineers reviewing the 25AA640X-I/ST datasheet, 25AA640X-I/ST pinout, 25AA640X-I/ST application, or 25AA640X-I/ST equivalent, this device serves as a drop-in replacement for legacy 25AA640 variants requiring TSSOP packaging with HOLD and WP functionality in space-constrained industrial control, sensor calibration storage, and firmware parameter retention designs.
Technical Context
The 25AA640X-I/ST implements a standard SPI Mode 0,0 interface with separate SI (data in) and SO (data out) lines, CS-controlled selection, and dedicated HOLD and WP pins for bus arbitration and hardware write protection. Its internal architecture includes a status register with WIP, WEL, BP0/BP1, and WPEN bits enabling configurable block protection and real-time write-status monitoring.
It uses self-timed erase/write cycles (max 5 ms), supports sequential read with automatic address roll-over, and incorporates power-on data protection via automatic WEL reset and built-in write-enable latch logic. The alternate pinout (per DS21223H-page 21) reassigns HOLD to Pin 1 and VCC to Pin 2 in the TSSOP package-distinct from standard SOIC/PDIP layouts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit), sufficient for storing configuration tables, calibration coefficients, or boot parameters in microcontroller-based systems |
| Interface | SPI Mode 0,0 (CPOL=0, CPHA=0), compatible with PIC, AVR, ARM Cortex-M, and most MCU SPI peripherals without protocol translation |
| Max Clock Frequency | 1 MHz at VCC = 1.8–5.5 V, enabling fast read/write in low-power embedded hosts without high-speed timing constraints |
| Write Cycle Time | 5 ms max per page or byte, deterministic timing for host firmware scheduling of non-blocking EEPROM updates |
| Endurance | 1 million erase/write cycles, supporting long-term field deployment in devices requiring frequent parameter logging or update tracking |
| Data Retention | 200+ years at +85°C, ensuring reliable storage of critical settings across product lifetime without refresh |
| Standby Current | 500 nA typical, minimizing quiescent drain in always-on battery-powered nodes such as IoT sensors or smart meters |
Pinout & Package
25AA640X-I/ST is packaged in an 8-lead Plastic Thin Shrink Small Outline Package (TSSOP), 4.4 mm body width, with JEDEC-standard lead pitch (0.65 mm) and Pb-free matte tin finish. This alternate-pinout variant swaps HOLD and VCC positions relative to standard SOIC/PDIP footprints.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | HOLD | Active-low pause signal: suspends ongoing SPI transfer without resetting state, enabling interrupt servicing on shared buses |
| 2 | VCC | Supply voltage input (1.8–5.5 V): powers internal charge pump, logic, and memory array; decoupling required within 10 mm |
| 3 | CS | Chip Select: active-low enables serial communication; high forces SO into high-Z to allow multi-device SPI sharing |
| 4 | SO | Serial Output: tri-state CMOS output delivering read data MSB-first on SCK falling edge |
| 5 | WP | Write-Protect: hardware lock for STATUS register when WPEN=1; grounded to prevent accidental writes during power transitions |
| 6 | VSS | Ground reference: common return path for VCC, I/O, and internal HV generator; must be low-impedance |
| 7 | SI | Serial Input: latches instruction/address/data on SCK rising edge; accepts standard CMOS logic levels |
| 8 | SCK | Serial Clock: synchronous timing reference; rise/fall times ≤2 μs required for reliable sampling at 1 MHz |
Key Features
| Feature | Design Value |
|---|---|
| Alternate TSSOP Pinout | Repositions HOLD to Pin 1 and VCC to Pin 2-enabling PCB layout optimization in dense industrial modules where standard SOIC routing conflicts |
| Hardware Write Protection | WP pin + WPEN bit combination prevents unintended STATUS register modification, safeguarding block-protection settings across power cycles |
| Page Write Buffer | 32-byte write buffer allows burst programming within same page boundary, reducing total write time vs. byte-by-byte operations |
| Power-On Write Disable | WEL automatically resets at power-up, eliminating risk of spurious writes during brown-out or cold-start conditions |
| Industrial Temp Range | Specified operation from –40°C to +85°C ensures reliability in factory automation, motor drives, and outdoor metering environments |
Applications
| Industrial Sensor Calibration | Embedded Firmware Parameter Storage |
|---|---|
Use Scenario: Storing factory-trimmed ADC offset/gain coefficients and temperature compensation tables in programmable logic controllers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during system initialization and runtime recalibration sequences. Use Value: Enables field-replaceable sensor modules with persistent calibration data independent of main MCU flash lifecycle limits. |
Use Scenario: Holding user-configurable settings (baud rate, network ID, alarm thresholds) in HVAC controllers and building automation gateways. IC Role / Device Role / Timing Role: SPI-accessible parameter store updated infrequently but retained across power loss and firmware upgrades. Use Value: Eliminates need for battery-backed RAM while maintaining >200-year data integrity under continuous thermal stress. |
| Smart Meter Tamper Logs | Medical Device Usage Counters |
Use Scenario: Recording timestamped tamper events (cover removal, magnetic interference) in ANSI C12.22-compliant electricity meters. IC Role / Device Role / Timing Role: High-endurance write log with atomic page writes ensuring no event loss during mains interruption. Use Value: Achieves 1M-cycle endurance for >10 years of daily logging at 300 events/day, validated per IEC 62055-31. |
Use Scenario: Tracking actuation cycles and service intervals in portable infusion pumps and diagnostic handhelds. IC Role / Device Role / Timing Role: Secure, low-power counter storage updated after each therapeutic delivery cycle. Use Value: Guarantees audit-trail persistence without external backup power, meeting FDA 21 CFR Part 11 electronic record requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SPI EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA640A-I/ST | Successor with enhanced ESD rating (6 kV HBM), improved AC timing margins, and updated qualification per AEC-Q100 Grade 3 | Preferred for new designs targeting automotive-adjacent industrial use cases requiring higher robustness | Select 25AA640A-I/ST if long-term supply assurance and extended qualification are prioritized over legacy footprint compatibility |
| AT25DF041A-SSH-T | 4 Mbit density, quad-SPI support, 85 MHz max clock, but lacks HOLD pin and uses different status register mapping | Suitable for high-throughput firmware storage but requires SPI driver rework and lacks hardware pause capability | Choose only when migrating to larger memory capacity and accepting software-level HOLD emulation via CS toggling |
Compared with 25AA640A-I/ST, the 25AA640X-I/ST offers identical pinout and function but lacks updated process and qualification; versus AT25DF041A-SSH-T, it trades density and speed for guaranteed HOLD functionality, simpler SPI implementation, and lower static power-making it optimal for resource-constrained, safety-critical parameter storage.
Availability
25AA640X-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration, embedded firmware parameter storage, smart meter tamper logs, and medical device usage counters requiring stable component supply across extended production lifecycles.
Supply support for 25AA640X-I/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 microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing infrastructure.
The 25AA640X-I/ST belongs to Microchip's legacy 25XX640 SPI EEPROM family, designed specifically for low-voltage, low-power, industrial-grade nonvolatile data storage in space-constrained embedded systems.
FAQ
What is the key functional difference between 25AA640X-I/ST and standard 25AA640-I/SN?
The 25AA640X-I/ST uses an alternate pinout in its TSSOP package: HOLD is assigned to Pin 1 and VCC to Pin 2, whereas the 25AA640-I/SN places CS on Pin 1 and VCC on Pin 8. This rearrangement optimizes routing in high-density PCB layouts but requires footprint verification before substitution. All electrical and functional specifications remain identical across both variants.
Does 25AA640X-I/ST support SPI Mode 1,1 or only Mode 0,0?
The 25AA640X-I/ST supports SPI Mode 0,0 exclusively-CPOL = 0 (idle clock low) and CPHA = 0 (sample on first clock edge). It does not support Mode 1,1 or other phase/polarity combinations. The device expects data setup on the rising edge of SCK and outputs valid data after the falling edge, as defined in DS21223H Section 1.2 and Figure 1-2.
How is hardware write protection implemented on 25AA640X-I/ST?
Hardware write protection on the 25AA640X-I/ST requires both the WP pin held low *and* the WPEN bit set high in the STATUS register. When enabled, this blocks writes to nonvolatile STATUS bits (BP0, BP1, WPEN) but permits normal memory reads and writes. If WPEN = 0, the WP pin is ignored-allowing full STATUS register access even with WP grounded.
What is the maximum clock frequency supported by 25AA640X-I/ST at 1.8 V supply?
At VCC = 1.8 V, the 25AA640X-I/ST supports a maximum clock frequency of 1 MHz, as specified in Table 1-2 (Param No. 1, FCLK) of DS21223H. This limit applies across the full industrial temperature range (–40°C to +85°C); operation above 1 MHz is not characterized or guaranteed at 1.8 V.
Can 25AA640X-I/ST be used in automotive applications requiring AEC-Q100 qualification?
No-25AA640X-I/ST is rated for industrial temperature range only (–40°C to +85°C) and is not AEC-Q100 qualified. For automotive use, Microchip recommends the 25LC640E variant (–40°C to +125°C, AEC-Q100 Grade 3 qualified) or the newer 25AA640A series, which includes automotive-grade versions with enhanced reliability testing.
25AA640X-I/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:
- 1 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25AA640X-I/ST FAQ
1.How can I place an order for 25AA640X-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA640X-I/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 25AA640X-I/ST reliable?
The price and inventory of 25AA640X-I/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA640X-I/ST is usually 5 days.
3.What payment methods are accepted for 25AA640X-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA640X-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA640X-I/ST?
25AA640X-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA640X-I/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 25AA640X-I/ST?
For technical support, including 25AA640X-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA640X-I/ST requirements.
6.How does Aetrix verify that 25AA640X-I/ST is sourced from the original manufacturer or authorized distributors?
All 25AA640X-I/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 25AA640X-I/ST meets industry standards.
7.What is the process for return or replacement of 25AA640X-I/ST?
All 25AA640X-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25AA640X-I/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 25AA640X-I/ST part is unused and in its original packaging.
Return procedure for 25AA640X-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25AA640X-I/ST 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
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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AT24C04C-SSHM-T
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24LC01BT-I/SN
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24AA02UIDT-I/OT
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AT24C08C-STUM-T
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