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Microchip Technology 25LC640AXT-E/ST
- Part No.:
- 25LC640AXT-E/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25LC640AXT-E/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,723
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Product details
Overview
25LC640AXT-E/ST from Microchip Technology Inc. is a 64-Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and AEC-Q100 qualified operation across –40°C to +125°C. It supports up to 10 MHz clock frequency at 4.5–5.5 V, features hardware write protection via WP pin and STATUS register, and delivers 1 million erase/write cycles with >200-year data retention for automotive and industrial control storage.
For engineers reviewing the 25LC640AXT-E/ST datasheet, 25LC640AXT-E/ST pinout, 25LC640AXT-E/ST application, or 25LC640AXT-E/ST equivalent, this page provides verified electrical specs, SPI timing constraints, HOLD/CS/WP functional behavior, package-specific pin mapping (TSSOP-8), and validated alternative parts for design-in continuity.
Technical Context
The 25LC640AXT-E/ST implements a standard SPI Mode 0,0 interface with separate SI (data in) and SO (data out) lines, requiring CS low and SCK synchronized communication. Its internal architecture includes a 32-byte page latch, HV generator for EEPROM programming, and status register with WIP, WEL, BP0/BP1, and WPEN bits for granular block protection.
It supports sequential read, byte/page write, and STATUS register access (RDSR/WRSR) with self-timed internal write cycles ≤5 ms. The HOLD pin enables mid-sequence suspension without resetting the SPI state machine, and hardware write protection is active only when WP = low AND WPEN = 1 - both conditions must be met for nonvolatile bit locking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit array), sufficient for firmware parameter tables or calibration data in space-constrained systems. |
| Interface | SPI-compatible serial bus (Mode 0,0), enabling direct connection to MCU SPI peripherals without protocol translation. |
| Max Clock Frequency | 10 MHz at VCC = 4.5–5.5 V; drops to 5 MHz at 2.5–4.5 V and 3 MHz at 1.8–2.5 V - dictates maximum throughput in host-controlled timing budgets. |
| Page Size | 32 bytes; page writes must not cross physical boundaries (e.g., address 0x1FF → 0x200 wraps), requiring software alignment checks. |
| Write Endurance | 1,000,000 erase/write cycles at +25°C, 5.5 V - supports frequent logging or configuration updates over product lifetime. |
| Data Retention | >200 years at +25°C - ensures long-term reliability for unpowered storage in automotive ECUs or industrial controllers. |
| Operating Temp | –40°C to +125°C (Extended range), qualified per AEC-Q100 Grade 1 - suitable for under-hood or high-ambient industrial environments. |
| Supply Voltage | 2.5 V to 5.5 V - compatible with 3.3 V and 5 V logic domains, eliminating level-shifting in mixed-voltage designs. |
Pinout & Package
25LC640AXT-E/ST is packaged in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm lead pitch, JEDEC MO-153 compliant, and marked "25LC640A" on top. Pin 1 is located at the top-left corner with a dot or notch indicator.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (CS) | Chip Select Input | Active-low enable; must go low before any SPI transaction and high after final bit to initiate internal write cycle. |
| 2 (SO) | Serial Data Output | Tri-state open-drain output; data valid after falling edge of SCK; high-impedance when CS high or HOLD low. |
| 3 (WP) | Write-Protect Input | Hardware lock for STATUS register nonvolatile bits when WPEN = 1; no effect if WPEN = 0 or WP = high. |
| 4 (VSS) | Ground Reference | Primary return path for all internal circuitry; must be low-impedance and decoupled near VCC pin. |
| 5 (SI) | Serial Data Input | Latches instruction/address/data on rising edge of SCK; requires setup/hold timing compliance per VCC voltage tier. |
| 6 (SCK) | Serial Clock Input | Master-generated clock; defines timing for SI sampling and SO update; rise/fall times ≤100 ns required. |
| 7 (HOLD) | Serial Bus Hold Input | Pauses ongoing SPI sequence when pulled low while SCK is low; resumes on rising edge of HOLD with SCK low. |
| 8 (VCC) | Power Supply | 2.5–5.5 V supply; internal power-on reset ensures WEL reset and SO high-Z at startup; bypass capacitor mandatory. |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Selectable via BP1/BP0 bits: protect none, upper 1/4 (0x1800–0x1FFF), upper 1/2 (0x1000–0x1FFF), or full array (0x0000–0x1FFF). |
| Self-Timed Write Cycle | ≤5 ms internal erase/write completion; eliminates need for external timeout polling - host can read STATUS register WIP bit to detect completion. |
| Power-On Data Protection | WEL automatically reset at power-up; WP pin inactive until WPEN bit set; prevents accidental writes during brown-out or reset sequences. |
| HOLD Functionality | Enables interrupt servicing without SPI re-synchronization; SO tri-states immediately on HOLD low, preserving address pointer and internal state. |
| AEC-Q100 Qualification | Qualified for automotive Grade 1 (–40°C to +125°C); includes stress testing for temperature cycling, HTOL, and ESD (>4 kV HBM) per automotive reliability standards. |
| Low Standby Current | 1 µA at 5.5 V, +85°C - critical for battery-backed systems where EEPROM must remain powered but idle for extended periods. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial PLC Configuration Storage |
|---|---|
Use Scenario: Storing adaptive fuel trim values, fault code history, and calibration offsets that persist across ignition cycles. IC Role / Device Role / Timing Role: Nonvolatile parameter memory accessed via SPI during boot and runtime; write operations occur infrequently but require guaranteed retention over 15+ years. Use Value: AEC-Q100 qualification and >200-year data retention ensure compliance with ISO 26262 ASIL-B functional safety requirements for persistent memory. |
Use Scenario: Holding user-defined I/O mapping, PID loop coefficients, and alarm thresholds in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: SPI-configurable storage element interfaced to ARM Cortex-M7 MCU; withstands repeated field updates during commissioning and maintenance. Use Value: 1M endurance cycles and 32-byte page write support enable efficient firmware patching and parameter backup without wear leveling overhead. |
| Medical Infusion Pump Calibration | Smart Energy Meter Firmware Parameters |
Use Scenario: Recording pump motor calibration constants, dose history logs, and safety-critical limit settings subject to FDA 21 CFR Part 11 audit trails. IC Role / Device Role / Timing Role: Secure, tamper-resistant memory with hardware write protection (WP + WPEN) preventing unauthorized modification of calibrated values. Use Value: Block protection allows locking of calibration sector while leaving user-adjustable parameters writable - meets IEC 62304 Class C software safety requirements. |
Use Scenario: Storing tariff schedules, metering constants, and cryptographic keys in ANSI C12.22-compliant smart meters operating in outdoor utility cabinets. IC Role / Device Role / Timing Role: High-temp EEPROM interfaced to TI MSP430FR59xx FRAM controller; operates reliably at +85°C ambient with minimal power draw. Use Value: 2.5–5.5 V supply range and 1 µA standby current extend battery life in AMI deployments where primary power may be intermittent. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA640AT-I/ST | Wider VCC range (1.8–5.5 V); supports 3 MHz operation down to 1.8 V; identical pinout and instruction set. | Better suited for 1.8 V microcontroller interfaces or ultra-low-power sleep modes where 2.5 V minimum is limiting. | Select when system operates below 2.5 V or requires extended low-voltage timing margin - otherwise 25LC640AXT-E/ST offers superior high-temp robustness. |
| AT25DF641-SSH-T | 64 Mbit density, quad SPI interface, 85 MHz max clock; different command set and no HOLD pin; SOIC-8 package only. | Targeted at high-speed firmware storage, not parameter/configuration EEPROM; lacks hardware write protection granularity. | Not a drop-in replacement; choose only for bandwidth-intensive code storage - not for legacy 25LC640A-based designs requiring pin compatibility and BP-level protection. |
Compared with 25AA640AT-I/ST, the 25LC640AXT-E/ST trades lower-voltage operation for guaranteed AEC-Q100 qualification and tighter high-temp AC timing; versus AT25DF641-SSH-T, it prioritizes deterministic write latency and hardware security over raw speed and density - making it optimal for safety-critical, low-bandwidth configuration storage.
Availability
25LC640AXT-E/ST is available at Aetrix Electronics and suitable for automotive ECU development, industrial PLC commissioning, and medical device calibration requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for 25LC640AXT-E/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 devices, and memory solutions, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.
The 25LC640A family is designed specifically for automotive and industrial applications demanding high reliability, extended temperature operation, and hardware-enforced data integrity - emphasizing AEC-Q100 qualification, 1M endurance, and configurable block protection.
FAQ
What is the maximum clock frequency supported by the 25LC640AXT-E/ST, and how does it vary with supply voltage?
The 25LC640AXT-E/ST supports up to 10 MHz at VCC = 4.5–5.5 V, 5 MHz at 2.5–4.5 V, and 3 MHz at 1.8–2.5 V. Since the 25LC640AXT-E/ST is rated for 2.5–5.5 V operation, its maximum usable clock is 10 MHz within its specified VCC range. This voltage-dependent scaling ensures timing margins are maintained across process and temperature variations - critical for deterministic SPI communication in automotive systems.
Does the 25LC640AXT-E/ST support hardware write protection, and how is it configured?
Yes, the 25LC640AXT-E/ST supports hardware write protection via the WP pin combined with the WPEN bit in the STATUS register. Protection is active only when WP = low AND WPEN = 1. When enabled, it locks nonvolatile bits in the STATUS register (BP0/BP1/WPEN), preventing accidental changes to block protection settings. The 25LC640AXT-E/ST's WP pin has no effect if WPEN = 0, allowing flexible system-level grounding without compromising configurability.
What is the page size of the 25LC640AXT-E/ST, and why does it matter for write operations?
The 25LC640AXT-E/ST has a fixed 32-byte page size. During page write, all bytes must reside within the same physical page boundary (e.g., addresses 0x0000–0x001F); crossing boundaries causes wraparound to the start of the current page. This constraint requires firmware to align write buffers and split multi-page updates - a key consideration for reliable parameter storage in the 25LC640AXT-E/ST, especially in safety-critical applications where incomplete writes must be avoided.
How does the HOLD pin function on the 25LC640AXT-E/ST, and what are its timing requirements?
The HOLD pin on the 25LC640AXT-E/ST suspends ongoing SPI communication without resetting the internal address pointer or command state. To activate HOLD, the pin must be pulled low while SCK is low; to resume, it must be raised high while SCK remains low. Violating this timing causes undefined behavior. This feature allows host MCUs to service higher-priority interrupts - a capability explicitly documented for the 25LC640AXT-E/ST in Microchip DS20001830G.
Is the 25LC640AXT-E/ST AEC-Q100 qualified, and what grade does it meet?
Yes, the 25LC640AXT-E/ST is AEC-Q100 qualified for Grade 1 (–40°C to +125°C), as confirmed in the official Microchip datasheet DS20001830G. This qualification includes stress testing for temperature cycling, high-temperature operating life (HTOL), and electrostatic discharge (ESD >4 kV HBM). The "E" suffix in the part number denotes Extended temperature range, and the "XT-E/ST" packaging variant is explicitly listed in the Device Selection Table for E-temp operation.
25LC640AXT-E/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:
- 2.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25LC640AXT-E/ST FAQ
1.How can I place an order for 25LC640AXT-E/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640AXT-E/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 25LC640AXT-E/ST reliable?
The price and inventory of 25LC640AXT-E/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC640AXT-E/ST is usually 5 days.
3.What payment methods are accepted for 25LC640AXT-E/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640AXT-E/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640AXT-E/ST?
25LC640AXT-E/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640AXT-E/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 25LC640AXT-E/ST?
For technical support, including 25LC640AXT-E/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640AXT-E/ST requirements.
6.How does Aetrix verify that 25LC640AXT-E/ST is sourced from the original manufacturer or authorized distributors?
All 25LC640AXT-E/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 25LC640AXT-E/ST meets industry standards.
7.What is the process for return or replacement of 25LC640AXT-E/ST?
All 25LC640AXT-E/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640AXT-E/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 25LC640AXT-E/ST part is unused and in its original packaging.
Return procedure for 25LC640AXT-E/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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