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Microchip Technology 25AA640AXT-I/ST
- Part No.:
- 25AA640AXT-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25AA640AXT-I/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,027
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Product details
Overview
25AA640AXT-I/ST 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 - deployed in automotive instrument clusters for calibration storage.
For engineers reviewing the 25AA640AXT-I/ST datasheet, 25AA640AXT-I/ST pinout, 25AA640AXT-I/ST application, or 25AA640AXT-I/ST equivalent, key selection criteria include industrial temperature support (−40°C to +85°C), TSSOP-8 package compatibility, SPI Mode 0,0/1,1 timing compliance, and block-level write protection granularity (none/¼/½/all array).
Technical Context
The 25AA640AXT-I/ST implements a standard SPI interface with separate SI (data-in) and SO (data-out) lines, CS-controlled device selection, and HOLD pin for transaction suspension without reset. Its internal architecture includes an 8-bit instruction register, page latches, and HV generator for EEPROM programming.
It supports four instruction modes: READ (0x03), WRITE (0x02), WREN/WRDI for write-enable control, and RDSR/WRSR for STATUS register access. Block protection is managed via BP0/BP1 bits controlling write-lock on upper 1/4 (1800h–1FFFh), upper 1/2 (1000h–1FFFh), or full array (0000h–1FFFh).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit) - sufficient for firmware configuration, sensor calibration tables, or boot parameters in resource-constrained embedded systems. |
| Interface | SPI-compatible serial bus (Mode 0,0 and 1,1) - enables direct connection to MCU SPI peripherals without protocol translation. |
| Page Size | 32 bytes - defines maximum contiguous write length per command; crossing page boundary wraps data within same physical page. |
| Write Cycle Time | ≤5 ms max - determines minimum time between successive write commands; impacts real-time logging latency. |
| Endurance | 1,000,000 erase/write cycles - supports frequent field-updatable parameters in industrial controllers or automotive ECUs. |
| Data Retention | >200 years at +25°C - ensures long-term reliability of stored calibration or security keys without refresh. |
| VCC Range | 1.8V to 5.5V - interoperable with both 3.3V and 5V logic domains, simplifying mixed-voltage board design. |
Pinout & Package
25AA640AXT-I/ST uses an 8-lead TSSOP package (3.0 mm × 4.4 mm, 0.65 mm pitch), RoHS-compliant and qualified to AEC-Q100 Grade 2 (−40°C to +105°C ambient) for automotive use.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable; deselecting forces SO into high-impedance state, enabling multi-device SPI bus sharing. |
| SO | Serial Data Output | Tri-state output; data shifted out on falling edge of SCK; high-Z when CS high or HOLD active. |
| WP | Write-Protect Pin | Hardware lock for STATUS register nonvolatile bits when WPEN=1; low = protection enabled, high = full write access. |
| VSS | Ground | Reference for all I/O and internal circuitry; must be connected before VCC during power sequencing. |
| SI | Serial Data Input | Latches instructions, addresses, and data on rising edge of SCK; requires setup/hold timing per AC specs. |
| SCK | Serial Clock Input | Synchronizes all SPI transfers; rising edge clocks input, falling edge updates output; max 10 MHz at 4.5–5.5V. |
| HOLD | Hold Input | Pauses ongoing SPI sequence when pulled low while SCK is low; resumes on rising edge of HOLD with SCK low. |
| VCC | Supply Voltage | 1.8V–5.5V operation; standby current ≤1 µA at 5.5V/85°C enables ultra-low-power battery-backed applications. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed write cycle | Internal 5 ms max erase/write eliminates need for external timeout management in host firmware. |
| Block write protection | Selectable via STATUS register BP0/BP1 bits - allows partial array locking for secure parameter partitioning (e.g., factory vs. user zones). |
| Power-on write disable | Write enable latch resets at power-up, preventing accidental writes during brown-out or reset conditions. |
| HOLD pin functionality | Enables interrupt servicing by host MCU without aborting SPI transaction - critical for real-time deterministic response. |
| ESD robustness | >4 kV HBM - meets industrial and automotive ESD immunity requirements without external protection diodes. |
Applications
| Automotive Instrument Cluster | Industrial PLC Configuration Storage |
|---|---|
Use Scenario: Storing odometer values, trip counters, and display brightness settings across ignition cycles. IC Role / Device Role / Timing Role: Nonvolatile parameter memory interfaced via SPI to cluster MCU; accessed during startup and runtime updates. Use Value: AEC-Q100 qualification and >200-year data retention ensure legal mileage integrity and eliminate recalibration after battery disconnect. | Use Scenario: Holding I/O mapping, PID tuning constants, and alarm thresholds in modular PLC backplanes. IC Role / Device Role / Timing Role: SPI-configurable EEPROM providing persistent configuration independent of main controller firmware. Use Value: 1M endurance supports daily field updates over 27 years; 32-byte page writes minimize bus occupancy during reconfiguration. |
| Medical Infusion Pump Calibration | Smart Energy Meter Firmware Patch Storage |
Use Scenario: Archiving flow-rate calibration coefficients and maintenance logs in Class II medical devices. IC Role / Device Role / Timing Role: Secure, tamper-resistant memory storing traceable calibration data accessible only after authentication handshake. Use Value: Hardware WP pin + STATUS register lock prevents unauthorized modification; RoHS compliance satisfies IEC 60601-1 material restrictions. | Use Scenario: Storing encrypted firmware patches and metering algorithm updates in utility-grade smart meters. IC Role / Device Role / Timing Role: SPI-bootloader-accessible memory holding signed update payloads prior to secure execution. Use Value: 1.8V operation enables direct connection to low-power meter SoC; 10 MHz interface accelerates patch validation and load times. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC640AT-I/ST | Requires VCC ≥ 2.5V; identical pinout, timing, and feature set otherwise. | Not suitable for 1.8V systems; otherwise drop-in replacement in 3.3V/5V designs. | Select when operating voltage is guaranteed ≥2.5V and cost optimization is prioritized. |
| AT25DF641-SSH-T | 64-Mbit DataFlash with sector erase; SPI quad I/O capable; no HOLD pin; different command set. | Higher density but incompatible instruction set and protection model; requires firmware rewrite. | Choose only when migrating to larger memory footprint and supporting quad-SPI host interface. |
Compared with 25LC640AT-I/ST, the 25AA640AXT-I/ST enables 1.8V operation for ultra-low-power systems; versus AT25DF641-SSH-T, it offers simpler SPI protocol, HOLD functionality, and proven AEC-Q100 qualification for automotive safety-critical storage.
Availability
25AA640AXT-I/ST is available at Aetrix Electronics and suitable for automotive instrument clusters, industrial PLCs, medical infusion pumps, and smart energy meters requiring stable component supply across extended product lifecycles.
Supply support for 25AA640AXT-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, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25AA640A family targets cost-sensitive, space-constrained embedded systems needing reliable, low-voltage serial EEPROM - especially automotive, industrial, and medical applications demanding AEC-Q100 qualification and long-term data integrity.
FAQ
What is the maximum SPI clock frequency supported by the 25AA640AXT-I/ST?
The 25AA640AXT-I/ST supports up to 10 MHz SPI clock frequency when VCC is 4.5V–5.5V, 5 MHz at 2.5V–4.5V, and 3 MHz at 1.8V–2.5V. These limits are defined in Table 1-2 of the DS20001830G datasheet and reflect actual timing margins under worst-case voltage and temperature conditions. The 25AA640AXT-I/ST must be operated within these AC specifications to guarantee reliable read/write operation.
Does the 25AA640AXT-I/ST support hardware write protection?
Yes, the 25AA640AXT-I/ST supports dual-layer hardware write protection: (1) the WP pin, when asserted low and WPEN bit set high in the STATUS register, disables writes to nonvolatile STATUS bits; (2) the STATUS register's BP0/BP1 bits enable software-configurable block protection of none, upper 1/4, upper 1/2, or entire memory array. This combination ensures robust defense against accidental or malicious overwrites in the 25AA640AXT-I/ST.
What package type is used by the 25AA640AXT-I/ST?
The 25AA640AXT-I/ST uses an 8-lead TSSOP package (3.0 mm × 4.4 mm body, 0.65 mm lead pitch), marked "25AA640A" and "XT-I/ST" per Microchip's packaging specification C04-057-T. This package is RoHS-compliant, thermally enhanced for industrial ambient operation, and compatible with standard surface-mount reflow profiles. The 25AA640AXT-I/ST pinout matches other 8-lead variants like SOIC and MSOP, enabling layout reuse where footprint constraints allow.
How does the HOLD pin function in the 25AA640AXT-I/ST?
The HOLD pin in the 25AA640AXT-I/ST suspends ongoing SPI communication without resetting the sequence: when pulled low while SCK is low, SI/SO/SCK enter high-impedance state and inputs are ignored except CS; resuming requires bringing HOLD high while SCK remains low. This allows host MCUs to service higher-priority interrupts and resume exactly where paused - a deterministic behavior confirmed in Figure 1-1 and Section 2.6 of the 25AA640AXT-I/ST datasheet.
Is the 25AA640AXT-I/ST qualified for automotive applications?
Yes, the 25AA640AXT-I/ST is AEC-Q100 qualified (Grade 2, −40°C to +105°C ambient), with extended temperature range support (−40°C to +125°C) and built-in power-on write protection. Its qualification covers HTOL, TC, ESD, and AC/DC stress testing per AEC standards. This makes the 25AA640AXT-I/ST suitable for automotive instrument clusters, body control modules, and ADAS subsystems where data integrity across thermal and electrical extremes is mandatory.
25AA640AXT-I/ST Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 10 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
25AA640AXT-I/ST FAQ
1.How can I place an order for 25AA640AXT-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA640AXT-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 25AA640AXT-I/ST reliable?
The price and inventory of 25AA640AXT-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 25AA640AXT-I/ST is usually 5 days.
3.What payment methods are accepted for 25AA640AXT-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA640AXT-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA640AXT-I/ST?
25AA640AXT-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA640AXT-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 25AA640AXT-I/ST?
For technical support, including 25AA640AXT-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA640AXT-I/ST requirements.
6.How does Aetrix verify that 25AA640AXT-I/ST is sourced from the original manufacturer or authorized distributors?
All 25AA640AXT-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 25AA640AXT-I/ST meets industry standards.
7.What is the process for return or replacement of 25AA640AXT-I/ST?
All 25AA640AXT-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25AA640AXT-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 25AA640AXT-I/ST part is unused and in its original packaging.
Return procedure for 25AA640AXT-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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