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Microchip Technology 25LC640AT-M/SN
- Part No.:
- 25LC640AT-M/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25LC640AT-M/SN.pdf
- Description:
- IC EEPROM 64KBIT SPI 10MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,261
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Product details
Overview
25LC640AT-M/SN from Microchip Technology is a 64 Kbit (8192 × 8) SPI Serial EEPROM with extended temperature range (−55°C to +125°C), 2.5–5.5 V supply, 32-byte page write capability, and hardware write protection via WP pin and STATUS register. It operates at up to 10 MHz clock frequency and supports HOLD functionality for interrupt-safe bus sharing in industrial control and automotive subsystems.
For engineers reviewing the 25LC640AT-M/SN datasheet, 25LC640AT-M/SN pinout, 25LC640AT-M/SN application, or 25LC640AT-M/SN equivalent, key selection criteria include guaranteed operation across −55°C to +125°C, self-timed 5 ms max write cycle, 1 million erase/write endurance, 200+ year data retention, and SPI Mode 0,0/1,1 compatibility with PIC® and other microcontrollers.
Technical Context
The 25LC640AT-M/SN implements a true SPI-compatible serial interface with separate SI (data in) and SO (data out) lines, CS-controlled selection, and HOLD pin for pausing ongoing transfers without sequence reset. Its internal architecture includes an 8-bit instruction register, page latches, HV generator for EEPROM programming, and status register with WIP, WEL, BP0/BP1, and WPEN bits.
Write operations require explicit WREN instruction before WRITE or WRSR commands; the write enable latch resets automatically after power-up, WRDI, WRSR, or successful WRITE. Block protection is configurable via BP0/BP1 to protect none, upper 1/4, upper 1/2, or entire memory array - all nonvolatile and retained across power cycles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit organization), sufficient for firmware parameter storage or calibration data in space-constrained designs |
| Interface | SPI-compatible serial bus (Mode 0,0 and Mode 1,1), requiring only CS, SCK, SI, SO - no I²C pull-up or arbitration overhead |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5V; 5 MHz at 2.5V ≤ VCC < 4.5V - enables fast read/write in high-throughput embedded logging |
| Page Size | 32 bytes - defines maximum contiguous write length per command; crossing page boundary wraps data within same page |
| Write Cycle Time | 5 ms maximum internal self-timed erase/write - eliminates need for external timing control or polling delay estimation |
| Endurance & Retention | 1,000,000 erase/write cycles and >200 years data retention - validated for long-life industrial deployments with infrequent updates |
| Operating Temp | −55°C to +125°C (Extended M grade) - qualified for under-hood automotive, downhole tools, and military-grade systems |
| Supply Voltage | 2.5V to 5.5V - interoperable with both 3.3V and 5V microcontroller I/O without level shifters |
Pinout & Package
8-lead SOIC (SN package, 3.90 mm body width), RoHS-compliant, tape-and-reel packaged (T suffix). Pin 1 marked with notch or dot; pin numbering follows standard SOIC convention (counterclockwise from notch).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low enable: pulls device into active mode; rising edge initiates internal write cycle after valid write sequence |
| SO (Pin 2) | Serial Data Output | Tri-state open-drain output; data shifted out on falling edge of SCK; high-impedance when CS high or HOLD low |
| WP (Pin 3) | Hardware Write-Protect Input | Low-active pin enabling nonvolatile STATUS register lock when WPEN = 1 - prevents accidental configuration changes in field |
| VSS (Pin 4) | Ground Reference | Primary return path for all internal circuitry; must be low-impedance connection to system ground plane |
| SI (Pin 5) | Serial Data Input | Latches instructions, addresses, and data on rising edge of SCK; sampled first after CS goes low |
| SCK (Pin 6) | Serial Clock Input | Synchronizes all SPI transactions; rising edge clocks data in, falling edge clocks data out on SO |
| HOLD (Pin 7) | Bus Hold Control | Pauses ongoing SPI transfer when pulled low during SCK low phase - allows host to service higher-priority interrupts |
| VCC (Pin 8) | Power Supply | 2.5–5.5 V operating range; decoupling capacitor (0.1 µF ceramic) required within 10 mm of pin for noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Configurable via STATUS register (BP0/BP1) to protect none, upper 1/4, upper 1/2, or full 64 Kbit array - enables secure boot code partitioning |
| Hardware Write Protection | WP pin + WPEN bit combination provides physical lock on STATUS register writes - prevents runtime corruption of protection settings |
| HOLD Functionality | Halts SPI communication mid-sequence without resetting address pointer - preserves state during interrupt servicing in real-time systems |
| Low-Power Operation | 5 μA standby current at 125°C ensures minimal battery drain in always-on monitoring nodes or energy-harvesting devices |
| Robust Electrical Ratings | 4 kV ESD protection on all pins and −0.6V to VCC+1.0V absolute input voltage range - enhances reliability in noisy industrial environments |
| Extended Temperature Grade | M-grade qualification (−55°C to +125°C) with full DC/AC specs guaranteed - eliminates derating concerns in harsh thermal profiles |
Applications
| Industrial Sensor Calibration Storage | Automotive ECU Configuration Memory |
|---|---|
Use Scenario: Storing factory-calibrated sensor coefficients and linearization tables in programmable logic controllers and distributed I/O modules. IC Role / Device Role / Timing Role: Nonvolatile parameter store accessed via SPI during system initialization and periodic recalibration routines. Use Value: 200+ year data retention and 1M endurance ensure calibration integrity over full product lifecycle without refresh cycles. |
Use Scenario: Holding vehicle-specific configuration data (e.g., VIN-derived settings, variant options) in engine control units and body control modules. IC Role / Device Role / Timing Role: SPI-configurable memory mapped to microcontroller's peripheral address space for runtime read/write access. Use Value: Hardware write protection (WP + WPEN) prevents unauthorized reprogramming of safety-critical configuration parameters. |
| Medical Device Usage Logs | Avionics System Boot Parameters |
Use Scenario: Recording operational timestamps, fault events, and usage counters in portable diagnostic equipment and infusion pumps. IC Role / Device Role / Timing Role: Low-power serial EEPROM interfaced to ARM Cortex-M MCU for timestamped event logging during battery operation. Use Value: 5 μA standby current at 125°C extends battery life in sealed, fanless enclosures with limited thermal dissipation. |
Use Scenario: Storing flight-critical boot parameters (e.g., sensor null offsets, mission-specific trim values) in airborne navigation and guidance subsystems. IC Role / Device Role / Timing Role: Radiation-tolerant (qualified) nonvolatile memory providing deterministic read latency (<100 ns output valid) for boot-time configuration loading. Use Value: Extended temperature range (−55°C to +125°C) and 10 MHz max clock support deterministic startup timing across environmental extremes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SPI Serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA640A-I/SN | Same 64 Kbit capacity, but Industrial (I) grade (−40°C to +85°C); identical pinout, timing, and instruction set | Lacks extended temperature qualification; unsuitable for under-hood or aerospace use cases requiring −55°C operation | Select 25AA640A-I/SN only for cost-sensitive commercial applications where ambient temperature stays within −40°C to +85°C |
| AT25DF041A-SH-B | 4 Mbit density, quad SPI interface, 85 MHz max clock; different instruction set and write protection scheme | Higher density and faster throughput, but requires firmware rewrite for quad-mode support and lacks HOLD pin | Choose AT25DF041A-SH-B when migrating to larger storage needs and can accommodate interface redesign and new driver development |
Compared with 25AA640A-I/SN, the 25LC640AT-M/SN delivers guaranteed operation at −55°C and +125°C - critical for automotive and defense systems - while maintaining identical software compatibility. Versus AT25DF041A-SH-B, it offers simpler SPI-legacy integration and HOLD-based interrupt handling, at the cost of lower density and speed.
Availability
25LC640AT-M/SN is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive ECUs, medical diagnostics equipment, and avionics subsystems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for 25LC640AT-M/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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design, manufacturing, and sales operations.
The 25LC640A family was designed specifically for reliable, low-power, SPI-based nonvolatile data storage in harsh-environment applications - emphasizing extended temperature operation, robust write protection, and seamless integration with PIC® and other embedded processors.
FAQ
What is the maximum clock frequency supported by the 25LC640AT-M/SN?
The 25LC640AT-M/SN supports up to 10 MHz clock frequency when VCC is 4.5V to 5.5V, and up to 5 MHz when VCC is 2.5V to less than 4.5V. These limits are specified across the full −55°C to +125°C operating range and ensure reliable setup/hold timing compliance per Table 1-2 in DS22144A.
Does the 25LC640AT-M/SN support page write operations, and what is the page size?
Yes, the 25LC640AT-M/SN supports page write operations with a fixed 32-byte page size. Up to 32 bytes can be written in a single command, provided all addresses reside within the same physical page boundary (e.g., 0x0000–0x001F). Crossing a page boundary causes wraparound within the current page, not continuation to the next page.
How does hardware write protection work on the 25LC640AT-M/SN?
Hardware write protection on the 25LC640AT-M/SN requires both the WP pin (Pin 3) to be low and the WPEN bit (bit 7 of STATUS register) to be set high. When enabled, this combination blocks writes to nonvolatile STATUS register bits (BP0, BP1, WPEN) while allowing normal memory reads, writes, and STATUS register reads.
What is the purpose of the HOLD pin on the 25LC640AT-M/SN?
The HOLD pin (Pin 7) on the 25LC640AT-M/SN suspends ongoing SPI communication without resetting the internal address pointer or instruction state. When asserted low during SCK low time, it places SI, SCK, and SO in high-impedance state, allowing the host microcontroller to service higher-priority interrupts and resume exactly where transmission left off.
Is the 25LC640AT-M/SN compatible with standard SPI Mode 0,0 and Mode 1,1?
Yes, the 25LC640AT-M/SN is fully compatible with SPI Mode 0,0 (CPOL = 0, CPHA = 0) and Mode 1,1 (CPOL = 1, CPHA = 1). Data is sampled on the rising edge of SCK (SI) and output on the falling edge (SO), matching standard SPI timing conventions used by PIC®, ARM, and most other microcontrollers with hardware SPI peripherals.
25LC640AT-M/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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:
- 10 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
25LC640AT-M/SN FAQ
1.How can I place an order for 25LC640AT-M/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640AT-M/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 25LC640AT-M/SN reliable?
The price and inventory of 25LC640AT-M/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC640AT-M/SN is usually 5 days.
3.What payment methods are accepted for 25LC640AT-M/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640AT-M/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640AT-M/SN?
25LC640AT-M/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640AT-M/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 25LC640AT-M/SN?
For technical support, including 25LC640AT-M/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640AT-M/SN requirements.
6.How does Aetrix verify that 25LC640AT-M/SN is sourced from the original manufacturer or authorized distributors?
All 25LC640AT-M/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 25LC640AT-M/SN meets industry standards.
7.What is the process for return or replacement of 25LC640AT-M/SN?
All 25LC640AT-M/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640AT-M/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 25LC640AT-M/SN part is unused and in its original packaging.
Return procedure for 25LC640AT-M/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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