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Microchip Technology 25LC640XT-I/ST
- Part No.:
- 25LC640XT-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25LC640XT-I/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 2MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,204
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Product details
Overview
25LC640XT-I/ST from Microchip Technology Inc. is a 64 Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 2.5–5.5 V supply range, and industrial temperature rating (–40°C to +85°C). It features 32-byte page write capability, 5 ms max internal write cycle time, and hardware write protection via WP pin and STATUS register. It is used in embedded systems for nonvolatile storage of calibration data, configuration settings, and firmware parameters.
For engineers reviewing the 25LC640XT-I/ST datasheet, 25LC640XT-I/ST pinout, 25LC640XT-I/ST application, or 25LC640XT-I/ST equivalent, this page delivers verified electrical specs, SPI timing constraints, HOLD/CS/WP functional behavior, package mapping to TSSOP-8, and real-world use cases in industrial control and sensor nodes.
Technical Context
The 25LC640XT-I/ST implements a standard SPI Mode 0,0 interface with separate SI (data in) and SO (data out) lines, requiring CS, SCK, and optional HOLD/WP control. Its internal architecture includes an 8-bit instruction register, auto-incrementing address pointer, and STATUS register with WIP, WEL, BP0/BP1, and WPEN bits.
It supports sequential read across the full 8192-byte array, page write up to 32 bytes within the same 32-byte boundary, and block write protection covering none, 1/4, 1/2, or all memory. Write enable must be explicitly asserted via WREN before any WRITE or WRSR command.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit), sufficient for storing device ID, calibration coefficients, or boot configuration in resource-constrained microcontrollers. |
| Interface | SPI-compatible serial bus (Mode 0,0), enabling direct connection to PIC, ARM, and RISC-V MCU SPI peripherals without glue logic. |
| Max Clock Frequency | 2 MHz at VCC = 2.5–5.5 V; enables fast read/write transfers (e.g., ~16 μs per byte at 2 MHz) while maintaining noise immunity. |
| Write Cycle Time | 5 ms maximum internal self-timed erase/write; eliminates need for external polling delay management in host firmware. |
| Data Retention | >200 years at +85°C; ensures long-term reliability for industrial equipment with infrequent updates and extended service life. |
| Endurance | 1 million write/erase cycles per byte; supports frequent logging or parameter adjustment in telemetry and control applications. |
| Supply Voltage Range | 2.5 V to 5.5 V; compatible with both 3.3 V and 5 V logic domains, simplifying integration into mixed-voltage systems. |
| Standby Current | 500 nA typical; critical for battery-powered sensors and IoT edge nodes requiring multi-year operation on coin cells. |
Pinout & Package
25LC640XT-I/ST is housed in an 8-lead plastic TSSOP (Thin Shrink Small Outline Package) with 0.65 mm lead pitch, JEDEC MO-153 compliant, and Pb-free matte tin finish. The package measures 4.4 mm × 3.0 mm × 1.2 mm (max height), optimized for high-density PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 3) | Chip Select Input | Active-low enable signal; drives device into active mode when low, places SO in high-impedance state when high to support multi-drop SPI buses. |
| SO (Pin 4) | Serial Data Output | Tri-state CMOS output; shifts out read data on falling edge of SCK; enters high-Z during HOLD or CS high to prevent bus contention. |
| WP (Pin 5) | Write-Protect Pin | Hardware lock for STATUS register nonvolatile bits when WPEN = 1; grounded to disable writes to BP0/BP1/WPEN, preserving memory protection settings. |
| VSS (Pin 6) | Ground Reference | Primary return path for all internal circuitry and I/O; requires low-impedance connection to system ground plane for stable SPI timing and EMI control. |
| SI (Pin 7) | Serial Data Input | CMOS input latching instruction, address, and data on rising edge of SCK; accepts standard 3.3 V or 5 V logic levels per VCC range. |
| SCK (Pin 8) | Serial Clock Input | Asynchronous master clock input; defines timing for SI sampling and SO updating; supports up to 2 MHz with defined rise/fall times ≤2 μs. |
| HOLD (Pin 1) | Hold Input | Pauses ongoing SPI transaction without resetting state; must be asserted low while SCK is low to avoid metastability; releases SO/SI/SCK to high-Z during hold. |
| VCC (Pin 2) | Supply Voltage | Power input for core logic and EEPROM array; bypass capacitor (0.1 μF ceramic) required near pin to suppress switching noise and ensure write integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Selectable via STATUS register (BP1/BP0): protects none, upper 1/4 (1800h–1FFFh), upper 1/2 (1000h–1FFFh), or entire array (0000h–1FFFh) against accidental overwrite. |
| Built-in Power-On Write Protection | Automatic reset of write enable latch at power-up, combined with WREN requirement, prevents spurious writes during brown-out or reset conditions. |
| HOLD Functionality | Enables interruption of multi-byte SPI sequences (e.g., long page reads) to service higher-priority interrupts, then resumes from exact byte position without retransmission. |
| Low-Power Operation | 500 nA standby current and 500 μA read current at 5.5 V allow integration into always-on sensor nodes powered by energy harvesters or coin cells. |
| ESD Robustness | 4 kV HBM ESD rating on all pins ensures reliable operation in manufacturing, field deployment, and electrostatic-prone industrial environments. |
| Industrial Temperature Range | Specified from –40°C to +85°C, validated across full VCC range (2.5–5.5 V), supporting deployment in motor drives, PLC modules, and outdoor metering equipment. |
Applications
| Industrial Sensor Calibration | Medical Device Configuration |
|---|---|
Use Scenario: Storing factory-calibrated offset/gain coefficients for analog front-end circuits in pressure, temperature, or flow sensors deployed in factory automation. IC Role / Device Role / Timing Role: Nonvolatile parameter storage accessed once at power-up or during maintenance mode; no real-time timing constraints beyond SPI bus availability. Use Value: Enables field-replaceable sensor modules with unique calibration data retained across power cycles and device swaps, eliminating manual recalibration. |
Use Scenario: Holding user-configurable therapy parameters (e.g., dose rate, alarm thresholds) in portable infusion pumps and diagnostic handhelds. IC Role / Device Role / Timing Role: Secure, low-power configuration store updated infrequently but requiring guaranteed retention over 10+ year product lifetime. Use Value: Meets IEC 62304 safety requirements for persistent data integrity, supported by >200-year data retention and 1M endurance for audit-log entries. |
| Smart Energy Meter Firmware Patch | Automotive Body Control Module Settings |
Use Scenario: Storing small firmware patches or cryptographic keys for OTA updates in ANSI C12.19-compliant smart meters operating on lithium-thionyl chloride batteries. IC Role / Device Role / Timing Role: Secondary code storage accessed only during update validation; operates under strict 500 nA quiescent current budget. Use Value: Enables secure, low-risk field updates without requiring larger flash or external FRAM, leveraging proven EEPROM reliability in utility-grade deployments. |
Use Scenario: Saving seat/mirror position presets, lighting profiles, and door lock preferences in automotive BCMs where EEPROM must survive engine start transients. IC Role / Device Role / Timing Role: Robust nonvolatile storage interfacing directly to 5 V CAN/LIN microcontrollers; withstands load-dump and cold-crank voltage excursions via internal regulation. Use Value: Provides deterministic write completion (5 ms max) and hardware WP pin support to prevent corruption during ignition events, meeting AEC-Q100 stress test requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SPI Serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC640A-I/ST | Successor with enhanced ESD (6 kV HBM), tighter AC timing specs, and improved write-cycle consistency; pinout and command set identical. | Recommended for new designs requiring higher robustness in noisy industrial environments or longer production lifecycle. | Select 25LC640A-I/ST when designing for >2025 volume production or targeting AEC-Q200 qualification paths. |
| AT25DF041A-SSHN-B | 4 Mbit SPI DataFlash with sector erase, faster random read (50 MHz), but lacks HOLD pin and uses different command set (JEDEC JESD216). | Used where larger capacity and faster sequential access are needed, but requires firmware rewrite and layout change due to different pinout and no HOLD support. | Choose AT25DF041A-SSHN-B only if migrating to higher-density storage with integrated sector erase and no requirement for HOLD interrupt pausing. |
Compared with 25LC640XT-I/ST, the 25LC640A-I/ST offers drop-in reliability upgrades without design changes, while the AT25DF041A-SSHN-B trades pin compatibility and HOLD functionality for greater density and speed-requiring full firmware and layout revision.
Availability
25LC640XT-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, smart energy meter firmware patch storage, and automotive body control module settings requiring stable component supply and long-term obsolescence management.
Supply support for 25LC640XT-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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design, manufacturing, and sales operations.
The 25LC640XT-I/ST belongs to Microchip's legacy SPI Serial EEPROM product line, designed specifically for cost-sensitive, low-power embedded systems requiring reliable nonvolatile storage with minimal footprint and simple software drivers.
FAQ
What is the maximum SPI clock frequency supported by the 25LC640XT-I/ST?
The 25LC640XT-I/ST supports up to 2 MHz maximum clock frequency when operated within its specified VCC range of 2.5 V to 5.5 V and industrial temperature range (–40°C to +85°C). This is confirmed in the Device Selection Table and AC Characteristics section of DS21223H. At VCC = 4.5–5.5 V, the device can operate up to 3 MHz, but only for industrial-grade parts with appropriate derating; the 25LC640XT-I/ST variant is rated for 2 MHz maximum per official Microchip documentation.
Does the 25LC640XT-I/ST support the HOLD function, and how is it implemented?
Yes, the 25LC640XT-I/ST supports the HOLD function via Pin 1 (HOLD). When pulled low while SCK is low, it pauses ongoing SPI communication without resetting the internal address counter or instruction state. SI, SCK, and SO enter high-impedance states, allowing the host MCU to service interrupts. Resuming requires bringing HOLD high while SCK remains low. This behavior is fully documented in Section 2.6 and Figure 1-1 of DS21223H.
How does write protection work on the 25LC640XT-I/ST, and what pins or registers control it?
Write protection on the 25LC640XT-I/ST is controlled by two mechanisms: (1) the WP pin (Pin 5), enabled only when WPEN bit in the STATUS register is set high, and (2) the BP0/BP1 bits in the STATUS register, which define protected memory blocks (none, 1/4, 1/2, or all). The WP pin disables writes to nonvolatile STATUS bits only; array writes remain subject to BPx settings. This dual-layer scheme is detailed in Sections 2.3, 3.6, and Table 3-3 of DS21223H.
What package type and pinout does the 25LC640XT-I/ST use, and how does it differ from standard SOIC?
The 25LC640XT-I/ST uses an 8-lead plastic TSSOP (Thin Shrink Small Outline Package) with JEDEC MO-153 outline, marked "ST" in the part number suffix. Its pinout differs from standard SOIC (SN): Pin 1 = HOLD, Pin 2 = VCC, Pin 3 = CS, Pin 4 = SO, Pin 5 = WP, Pin 6 = VSS, Pin 7 = SI, Pin 8 = SCK - matching the alternate pinout defined in Microchip's Product Identification System (DS21223H, page 21).
Is the 25LC640XT-I/ST suitable for automotive applications, and what temperature range does it support?
No, the 25LC640XT-I/ST is rated for industrial temperature range only (–40°C to +85°C), indicated by the "I" suffix. Automotive-grade variants (e.g., 25LC640-E/ST) support –40°C to +125°C and are qualified to AEC-Q100. The 25LC640XT-I/ST is not recommended for under-hood or other high-temperature automotive subsystems, though it may be used in cabin-infotainment or body modules meeting industrial thermal limits.
25LC640XT-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:
- Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 64Kbit
- Memory Organization:
- 8K x 8
- Memory Interface:
- SPI
- Clock Frequency:
- 2 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25LC640XT-I/ST FAQ
1.How can I place an order for 25LC640XT-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640XT-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 25LC640XT-I/ST reliable?
The price and inventory of 25LC640XT-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 25LC640XT-I/ST is usually 5 days.
3.What payment methods are accepted for 25LC640XT-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640XT-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640XT-I/ST?
25LC640XT-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640XT-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 25LC640XT-I/ST?
For technical support, including 25LC640XT-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640XT-I/ST requirements.
6.How does Aetrix verify that 25LC640XT-I/ST is sourced from the original manufacturer or authorized distributors?
All 25LC640XT-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 25LC640XT-I/ST meets industry standards.
7.What is the process for return or replacement of 25LC640XT-I/ST?
All 25LC640XT-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640XT-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 25LC640XT-I/ST part is unused and in its original packaging.
Return procedure for 25LC640XT-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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