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Microchip Technology 25LC256X-I/ST
- Part No.:
- 25LC256X-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25LC256X-I/ST.pdf
- Description:
- IC EEPROM 256KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,181
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Product details
Overview
25LC256X-I/ST from Microchip Technology Inc. is a 256 Kbit (32,768 × 8) SPI Serial EEPROM with 64-byte page write capability, 10 MHz max clock frequency, and industrial temperature range (–40°C to +85°C). It operates from 2.5V to 5.5V, features hardware write protection via WP pin and STATUS register, and is used for nonvolatile configuration storage in microcontroller-based embedded systems.
For engineers reviewing the 25LC256X-I/ST datasheet, 25LC256X-I/ST pinout, 25LC256X-I/ST application, or 25LC256X-I/ST equivalent, this page delivers verified electrical specs, SPI timing constraints, HOLD/CS control behavior, block protection mapping, and real-world use context for reliable system integration.
Technical Context
The 25LC256X-I/ST implements a standard SPI Mode 0,0 (CPOL=0, CPHA=0) interface with separate SI/SO lines, requiring CS low and HOLD high for active operation. Its internal architecture includes an 8-bit instruction register, page latches, HV generator for EEPROM programming, and a STATUS register with WIP/WEL/BP0/BP1 bits.
Write operations require explicit WREN instruction before WRITE or WRSR; CS rising edge initiates self-timed internal write cycle (≤5 ms). Block protection supports four configurations (none, upper 1/4, upper 1/2, or full array), controlled by BP0/BP1 bits and enabled only when WPEN=1 and WP=low.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - provides sufficient space for firmware parameters, calibration data, or device identity storage in resource-constrained systems. |
| Interface | SPI-compatible serial bus (Mode 0,0) - enables direct connection to MCU SPI peripherals without protocol translation or glue logic. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5V - supports high-speed read/write bursts while maintaining compatibility with common MCU SPI clock dividers. |
| Page Size | 64 bytes - defines maximum contiguous write length per CS assertion; crossing page boundaries wraps data within same physical page. |
| Write Cycle Time | ≤5 ms (TWC) - determines minimum time between successive write commands; STATUS register WIP bit must be polled to avoid bus contention. |
| Endurance & Retention | 1,000,000 erase/write cycles; >200 years data retention - ensures long-term reliability in field-deployed industrial controllers and automotive modules. |
| Supply Voltage | 2.5V to 5.5V - allows interoperability with both 3.3V and 5V logic domains without level-shifting circuitry. |
| Temp Range | Industrial: –40°C to +85°C - qualified for use in factory automation, motor drives, and outdoor IoT gateways. |
Pinout & Package
25LC256X-I/ST is housed in an 8-lead TSSOP package (4.4 mm body width), RoHS-compliant, with gull-wing leads and standard JEDEC MO-153 footprint. Pin 1 is marked by a dot or beveled corner; orientation follows standard TSSOP pin 1 indicator (top-left when notch or mark faces up).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable signal; falling edge initiates command sequence; rising edge triggers internal write cycle after valid WRITE/WRSR. |
| SO | Serial Data Output | Tri-state open-drain output; data shifted out on SCK falling edge during READ; high-impedance when CS high or HOLD low. |
| WP | Write-Protect Pin | Hardware lock for STATUS register writes when WPEN=1; no effect on memory writes unless BP bits are set and WPEN=1. |
| VSS | Ground Reference | Primary return path for all internal circuits; must be low-impedance and decoupled near VCC pin. |
| SI | Serial Data Input | CMOS input; latches instruction/address/data on SCK rising edge; requires setup/hold timing compliance per VCC voltage grade. |
| SCK | Serial Clock Input | Asynchronous master clock; defines timing for SI sampling and SO updates; max 10 MHz at 4.5–5.5V. |
| HOLD | Hold Input | Pauses ongoing SPI transaction without resetting state; must be asserted while SCK is low; tri-states SO immediately. |
| VCC | Supply Voltage | Power rail for core logic and EEPROM programming; requires 0.1 µF ceramic decoupling capacitor placed ≤5 mm from pin. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed write cycle | Internal 5 ms max erase/write eliminates need for external timing control or busy-wait loops beyond WIP polling. |
| Block write protection | Configurable via BP0/BP1 bits to protect none, upper 1/4 (6000h–7FFFh), upper 1/2 (4000h–7FFFh), or full array (0000h–7FFFh). |
| Hardware + software write protection | WP pin + WPEN bit enables dual-layer protection: physical pin lock and programmable register lock for robust security. |
| HOLD function | Enables interrupt servicing during SPI transfers without losing command context or requiring retransmission of address/instruction. |
| Low-power standby | 1 µA max ICCS at 5.5V/85°C - suitable for battery-backed systems where quiescent current directly impacts runtime. |
| AEC-Q100 qualification | Qualified for automotive applications (Grade 3), confirming reliability under thermal cycling, vibration, and ESD stress per AEC standards. |
Applications
| Industrial PLC Configuration Storage | Automotive ECU Calibration Data |
|---|---|
|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and fault log history in programmable logic controllers operating in factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via SPI during boot and runtime; supports infrequent writes but frequent reads with guaranteed data integrity over 200+ years. Use Value: Eliminates need for battery-backed SRAM; withstands wide temperature swings and electrical noise typical in industrial settings. |
Use Scenario: Holding engine calibration maps, sensor offset corrections, and diagnostic trouble code (DTC) history in engine control units. IC Role / Device Role / Timing Role: SPI-connected EEPROM providing deterministic read latency (<160 ns output valid) and secure write protection against unintended updates during vehicle operation. Use Value: AEC-Q100 qualification ensures reliability across automotive temperature range; block protection prevents corruption of critical calibration sectors. |
| Medical Device Settings Backup | Smart Meter Firmware Parameters |
|
Use Scenario: Preserving user-configured alarm thresholds, measurement units, and calibration offsets in portable diagnostic equipment. IC Role / Device Role / Timing Role: Low-power (1 µA standby) nonvolatile memory enabling long battery life; write-enable latch prevents accidental overwrites during power transitions. Use Value: Meets medical safety requirements for data persistence; >1M endurance supports repeated recalibration over device lifetime. |
Use Scenario: Storing tariff schedules, communication keys, and metering constants in utility smart meters deployed outdoors for 15+ years. IC Role / Device Role / Timing Role: High-reliability EEPROM with >200-year data retention and ESD protection (>4 kV) for harsh field environments. Use Value: RoHS-compliant TSSOP package simplifies automated assembly; 64-byte page writes optimize firmware update efficiency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SPI Serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA256-I/ST | Wider VCC range (1.8–5.5V); identical pinout, timing, and memory organization; lower 1.8V operation enables compatibility with ultra-low-power MCUs. | Preferred in battery-powered or energy-harvesting systems where supply may dip below 2.5V; not suitable if system exclusively uses 5V rails with no margin. | Select 25AA256-I/ST when operating below 2.5V is required; otherwise, 25LC256X-I/ST offers tighter VCC tolerance and higher noise immunity at 2.5–5.5V. |
| AT25SF256A-SSHD-B | Quad SPI interface (QPI), 133 MHz max clock, 2.7–3.6V only; integrated security features (secure OTP, hardware reset protection); different command set and pinout. | Targeted at secure firmware storage in connected devices; incompatible with standard SPI-only hosts without driver modification. | Choose AT25SF256A-SSHD-B only when Quad SPI bandwidth or hardware security features are mandatory; not a drop-in replacement for 25LC256X-I/ST. |
Compared with 25AA256-I/ST, the 25LC256X-I/ST trades wider voltage flexibility for improved noise margin above 2.5V; versus AT25SF256A-SSHD-B, it sacrifices speed and security for universal SPI compatibility and simpler firmware integration.
Availability
25LC256X-I/ST is available at Aetrix Electronics and suitable for industrial PLCs, automotive ECUs, medical diagnostics, and smart metering applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for 25LC256X-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 25LC256X-I/ST belongs to Microchip's legacy SPI Serial EEPROM product line, designed specifically for cost-sensitive, high-reliability embedded systems requiring simple, proven nonvolatile storage with minimal MCU resource overhead.
FAQ
What is the maximum clock frequency supported by the 25LC256X-I/ST?
The 25LC256X-I/ST supports up to 10 MHz clock frequency when VCC is 4.5V to 5.5V, 5 MHz at 2.5V to <4.5V, and 3 MHz at 1.8V to <2.5V. Since the 25LC256X-I/ST is rated for 2.5–5.5V operation, its maximum usable clock is 10 MHz. This enables fast read throughput in systems with capable SPI peripherals.
Does the 25LC256X-I/ST support page write operations, and what is the page size?
Yes, the 25LC256X-I/ST supports page write operations with a fixed page size of 64 bytes. A single WRITE instruction can load up to 64 consecutive bytes into the page buffer before initiating the internal write cycle. Attempting to cross a 64-byte boundary wraps data to the start of the same page, so software must enforce alignment.
How does hardware write protection work on the 25LC256X-I/ST?
Hardware write protection on the 25LC256X-I/ST requires both the WP pin to be low and the WPEN bit (STATUS register bit 7) to be set high. When enabled, this combination blocks writes to the nonvolatile STATUS register bits (BP0, BP1, WPEN), but does not affect memory array writes unless block protection bits are also set.
What is the purpose of the HOLD pin on the 25LC256X-I/ST?
The HOLD pin on the 25LC256X-I/ST suspends an ongoing SPI transaction without resetting the internal state. When pulled low while SCK is low, it places SO, SI, and SCK in high-impedance and pauses the command sequence. Resuming requires bringing HOLD high while SCK remains low - enabling MCU interrupt handling without reinitializing communication.
Is the 25LC256X-I/ST qualified for automotive applications?
Yes, the 25LC256X-I/ST is AEC-Q100 qualified (Grade 3: –40°C to +85°C), confirming its suitability for automotive applications such as body control modules, instrument clusters, and ADAS subsystems where reliability under thermal, mechanical, and electrical stress is critical.
25LC256X-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:
- 256Kbit
- Memory Organization:
- 32K 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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25LC256X-I/ST FAQ
1.How can I place an order for 25LC256X-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC256X-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 25LC256X-I/ST reliable?
The price and inventory of 25LC256X-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 25LC256X-I/ST is usually 5 days.
3.What payment methods are accepted for 25LC256X-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC256X-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC256X-I/ST?
25LC256X-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC256X-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 25LC256X-I/ST?
For technical support, including 25LC256X-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC256X-I/ST requirements.
6.How does Aetrix verify that 25LC256X-I/ST is sourced from the original manufacturer or authorized distributors?
All 25LC256X-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 25LC256X-I/ST meets industry standards.
7.What is the process for return or replacement of 25LC256X-I/ST?
All 25LC256X-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC256X-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 25LC256X-I/ST part is unused and in its original packaging.
Return procedure for 25LC256X-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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