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Microchip Technology 25LC640X-I/ST
- Part No.:
- 25LC640X-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25LC640X-I/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 2MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:500
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Product details
Overview
25LC640X-I/ST from Microchip Technology Inc. is a 64 Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page write capability, and industrial temperature range (–40°C to +85°C). It operates at up to 2 MHz clock frequency with 2.5–5.5 V supply, features hardware write protection via WP pin and STATUS register, and supports HOLD for interrupt-safe serial communication in embedded control systems.
For engineers reviewing the 25LC640X-I/ST datasheet, 25LC640X-I/ST pinout, 25LC640X-I/ST application, or 25LC640X-I/ST equivalent, this page delivers verified electrical specs, TSSOP-8 pin mapping, real-world use cases in power management and firmware storage, and two validated alternative parts with documented functional and packaging differences.
Technical Context
The 25LC640X-I/ST implements a standard SPI Mode 0,0 interface with separate SI/SO lines, CS-controlled selection, and dedicated HOLD and WP pins for deterministic bus arbitration and data integrity. Its internal architecture includes an 8-bit instruction register, auto-incrementing address pointer, and nonvolatile STATUS register with BP0/BP1 block protection bits.
It uses low-power CMOS technology with typical read current of 500 μA, standby current of 500 nA, and self-timed 5 ms max write cycle. The device supports sequential read, page write (up to 32 bytes within same page), and programmable array protection covering none, 1/4, 1/2, or all memory segments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit) - provides sufficient nonvolatile storage for configuration data, calibration tables, or boot parameters in space-constrained designs. |
| Interface | SPI Mode 0,0 (CPOL=0, CPHA=0) - ensures compatibility with most microcontroller SPI peripherals without custom timing logic. |
| Max Clock Frequency | 2 MHz at VCC = 2.5–5.5 V - enables fast read/write transfers while maintaining signal integrity on standard PCB traces. |
| Write Cycle Time | 5 ms maximum - defines worst-case latency for persistent data commits; critical for fail-safe logging and state retention. |
| Data Retention | >200 years - guarantees long-term reliability for industrial equipment with infrequent field updates. |
| Endurance | 1 million erase/write cycles - supports frequent parameter tuning in test instrumentation or adaptive control systems. |
| Supply Voltage | 2.5 V to 5.5 V - allows direct integration into 3.3 V or 5 V logic domains without level-shifting circuitry. |
| Operating Temperature | –40°C to +85°C (Industrial) - qualified for deployment in factory automation, motor drives, and outdoor electronics enclosures. |
Pinout & Package
25LC640X-I/ST is housed in an 8-pin Plastic Thin Shrink Small Outline Package (TSSOP) with 0.65 mm lead pitch and 4.4 mm body width. This alternate pinout variant (denoted by "X" suffix) reassigns pin positions compared to standard SOIC/PDIP versions - specifically, HOLD occupies Pin 1 and VCC occupies Pin 2 per Microchip's package marking specification.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (HOLD) | Hold Input | Pauses ongoing SPI transaction without resetting sequence; tri-states SO when asserted low, enabling host CPU to service higher-priority interrupts. |
| Pin 2 (VCC) | Supply Voltage | Primary power input (2.5–5.5 V); decoupling capacitor placement near this pin is mandatory for stable read/write operation. |
| Pin 3 (CS) | Chip Select Input | Active-low enable signal; must be held low for entire SPI frame; rising edge after WRITE initiates internal write cycle. |
| Pin 4 (SO) | Serial Data Output | Tri-state open-drain output; shifts out memory data MSB-first on falling SCK edge during READ operations. |
| Pin 5 (WP) | Write-Protect Pin | Hardware lock for STATUS register when WPEN bit is set; grounded to disable nonvolatile bit writes while permitting array reads/writes. |
| Pin 6 (VSS) | Ground | Reference return path for all I/O and internal circuitry; requires low-impedance connection to system ground plane. |
| Pin 7 (SI) | Serial Data Input | Latches instruction, address, and data bits on rising SCK edge; accepts standard SPI command set including RDSR, WRSR, READ, WRITE. |
| Pin 8 (SCK) | Serial Clock Input | Master-generated clock synchronizing all data transfers; timing constraints require min. 150 ns high/low times at 2 MHz operation. |
Key Features
| Feature | Design Value |
|---|---|
| Alternate Pinout (TSSOP) | Reordered pin assignment (HOLD=1, VCC=2) enables layout optimization in dense PCBs where standard SOIC pinout causes routing congestion. |
| Block Write Protection | Configurable via BP0/BP1 bits to protect 0%, 25%, 50%, or 100% of memory - prevents accidental overwrite of critical bootloader or calibration sectors. |
| Power-On Write Disable | Write enable latch resets at power-up, requiring explicit WREN instruction before any write - eliminates spurious writes during brown-out or reset conditions. |
| HOLD Functionality | Halts SPI communication mid-frame with no loss of state; resumes from exact byte position upon HOLD deassertion - essential for real-time OS context switching. |
| Low Standby Current | 500 nA typical at VCC = 2.5–5.5 V - extends battery life in portable diagnostic tools or energy-harvesting sensor nodes. |
| ESD Robustness | >4 kV HBM rating - withstands handling and board-level ESD events common in manufacturing and field service environments. |
Applications
| Industrial Power Supply Configuration | Firmware Parameter Storage |
|---|---|
Use Scenario: Storing trim values, fault thresholds, and operating modes in AC/DC power modules with digital control loops. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed during startup and runtime via SPI by digital PWM controller. Use Value: Enables field-upgradable calibration without firmware reflash; 200-year data retention ensures settings persist across product lifetime. |
Use Scenario: Holding user-modifiable settings (e.g., display brightness, alarm limits) in medical infusion pumps. IC Role / Device Role / Timing Role: Dedicated SPI EEPROM interfaced to ARM Cortex-M0+ MCU for safe, atomic parameter updates. Use Value: Page-write capability (32 bytes) allows batch saving of related parameters; WP pin prevents corruption during power interruption. |
| Automotive Body Control Module | Smart Energy Meter Calibration |
Use Scenario: Recording seat position memory, mirror presets, and lighting profiles in vehicle BCMs. IC Role / Device Role / Timing Role: SPI slave storing user preferences with HOLD support to pause writes during CAN bus arbitration. Use Value: Industrial temp grade (–40°C to +85°C) meets automotive cabin requirements; 1M endurance supports daily adjustments over 10+ years. |
Use Scenario: Storing metrology IC calibration coefficients and tariff schedules in ANSI C12.20-compliant meters. IC Role / Device Role / Timing Role: Secure nonvolatile storage isolated from main processor; accessed only during factory calibration or firmware update. Use Value: Hardware write protection (WP + WPEN) prevents unauthorized coefficient modification; 500 nA standby current minimizes battery drain in backup mode. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SPI EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC640-I/ST | Standard pinout TSSOP-8 (HOLD=7, VCC=8); identical electrical specs and memory map. | Requires PCB layout revision if replacing 25LC640X-I/ST due to swapped HOLD/VCC positions. | Select when redesigning for standard pin compatibility or sourcing legacy layouts. |
| 25AA640-I/ST | 1.8–5.5 V supply range; 1 MHz max clock; same 64 Kbit density and TSSOP-8 package. | Better suited for mixed-voltage systems with 1.8 V logic; lower speed acceptable for infrequent configuration access. | Choose for ultra-low-voltage operation or where 1 MHz SPI bandwidth suffices. |
Compared with 25LC640X-I/ST, the 25LC640-I/ST offers identical functionality but demands PCB layout changes due to pin reordering, while the 25AA640-I/ST trades speed and voltage margin for broader supply flexibility - making it preferable in battery-powered or multi-rail designs.
Availability
25LC640X-I/ST is available at Aetrix Electronics and suitable for industrial power supplies, medical devices, automotive body controllers, and smart metering systems requiring stable component supply, long-term obsolescence planning, and traceable sourcing.
Supply support for 25LC640X-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 operations.
The 25LC640X-I/ST belongs to Microchip's serial EEPROM product line, engineered for reliable nonvolatile data storage in resource-constrained embedded systems where SPI interface simplicity, low power, and industrial-grade reliability are critical.
FAQ
What is the key distinction between 25LC640X-I/ST and 25LC640-I/ST?
The 25LC640X-I/ST uses an alternate pinout in its TSSOP-8 package: HOLD is on Pin 1 and VCC on Pin 2, whereas the standard 25LC640-I/ST places HOLD on Pin 7 and VCC on Pin 8. All electrical specifications, memory organization, and instruction set remain identical between the two variants. This pin swap is intended to improve PCB routing in high-density layouts.
Does 25LC640X-I/ST support SPI Mode 1,1 or only Mode 0,0?
The 25LC640X-I/ST supports only SPI Mode 0,0 (CPOL = 0, CPHA = 0), as confirmed by its timing diagrams and functional description. Data is sampled on the rising edge of SCK and shifted out on the falling edge. Attempting Mode 1,1 will result in misaligned sampling and communication failure.
How does the HOLD pin function during an active write cycle?
The HOLD pin cannot suspend an internal write cycle once initiated; it only pauses serial communication (READ/WRITE instructions) before the CS-high transition that triggers the internal 5 ms write. If HOLD is asserted during a write sequence prior to CS going high, the device halts further instruction parsing but completes the pending write after CS rises - ensuring data integrity.
Can 25LC640X-I/ST be used with a 1.8 V supply?
No, the 25LC640X-I/ST requires a minimum supply voltage of 2.5 V and is not rated for 1.8 V operation. For 1.8 V systems, Microchip recommends the 25AA640-I/ST, which is specified down to 1.8 V and shares the same 64 Kbit density and TSSOP-8 package option.
What happens to the write enable latch after issuing a WRITE instruction?
After a successful WRITE instruction completes (i.e., CS is brought high following the final data bit), the write enable latch is automatically reset. This means a new WREN instruction must be issued before any subsequent write operation - a safety mechanism preventing unintended writes during software glitches or power transients.
25LC640X-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:
- 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
25LC640X-I/ST FAQ
1.How can I place an order for 25LC640X-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640X-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 25LC640X-I/ST reliable?
The price and inventory of 25LC640X-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 25LC640X-I/ST is usually 5 days.
3.What payment methods are accepted for 25LC640X-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640X-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640X-I/ST?
25LC640X-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640X-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 25LC640X-I/ST?
For technical support, including 25LC640X-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640X-I/ST requirements.
6.How does Aetrix verify that 25LC640X-I/ST is sourced from the original manufacturer or authorized distributors?
All 25LC640X-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 25LC640X-I/ST meets industry standards.
7.What is the process for return or replacement of 25LC640X-I/ST?
All 25LC640X-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640X-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 25LC640X-I/ST part is unused and in its original packaging.
Return procedure for 25LC640X-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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