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Microchip Technology 25LC256-I/ST

Name: 25LC256-I/ST
Brand: Microchip Technology
SKU: 25LC256-I/ST
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 25LC256-I/ST

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 8-TSSOP (0.173", 4.40mm Width)

Datasheet:: 25LC256-I/ST.pdf

Description:: IC EEPROM 256KBIT SPI 8TSSOP

Quantity:: RFQ Add To RFQ list

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Inventory:3,712

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Product details

Overview

25LC256-I/ST from Microchip Technology Inc. is a 256 Kbit SPI Serial EEPROM with 32,768 × 8-bit organization, 64-byte page size, and industrial temperature range (–40°C to +85°C). It operates from 2.5V to 5.5V, supports up to 10 MHz clock frequency, and delivers 5 mA max write current at 5.5V - used for nonvolatile configuration storage in microcontroller-based embedded systems.

For engineers reviewing the 25LC256-I/ST datasheet, 25LC256-I/ST pinout, 25LC256-I/ST application, or 25LC256-I/ST equivalent, key selection criteria include SPI interface compatibility, hardware write protection via WP pin, HOLD functionality for interrupt-safe bus sharing, and guaranteed 1 million erase/write cycles with >200-year data retention.

Technical Context

The 25LC256-I/ST implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data in) and SO (data out) lines, requiring only CS, SCK, SI, SO, WP, HOLD, VCC, and VSS. Its internal architecture includes an 8-bit instruction register, status register with WIP/WEL/BP bits, and page latches enabling 64-byte burst writes within aligned physical pages.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms), while read operations support sequential addressing with automatic address roll-over at 0x7FFF. Hardware write protection is configurable via 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-bit) - sufficient for firmware parameter tables, calibration data, or device identity storage in resource-constrained systems.
Interface	SPI-compatible serial bus (Mode 0,0) - interoperable with PIC® and most MCU SPI peripherals without protocol translation.
Page Size	64 bytes - defines maximum contiguous write length; crossing page boundary wraps data to start of same page, requiring software alignment.
Max Clock Frequency	10 MHz at VCC ≥ 4.5V - enables fast read/write throughput (up to ~1.25 MB/s theoretical read rate) in high-speed control loops.
Endurance & Retention	1,000,000 erase/write cycles and >200 years data retention - validated for long-life industrial logging and infrequently updated configuration storage.
Supply Voltage	2.5V to 5.5V - supports direct interfacing with 3.3V and 5V logic domains without level shifting.
Operating Temp	–40°C to +85°C (Industrial grade) - qualified for deployment in automotive body electronics, industrial PLCs, and outdoor metering equipment.

Pinout & Package

25LC256-I/ST uses an 8-lead TSSOP package (4.4 mm body width, JEDEC MO-153), pin-compatible with other 25XX256 variants in SOIC, PDIP, and DFN packages. Pin numbering follows standard TSSOP orientation with Pin 1 (CS) at top-left corner when notch is oriented upward.

Pin/Terminal	Circuit Role	Design Meaning
CS	Chip Select Input	Active-low enable signal; must be low for all SPI transactions; rising edge after valid write sequence triggers internal write cycle.
SO	Serial Data Output	Tri-state output delivering memory contents on falling edge of SCK; enters high-Z when CS is high or HOLD is asserted.
WP	Write-Protect Pin	Hardware lock for STATUS register nonvolatile bits; effective only when WPEN bit = 1; allows selective block protection independent of software WREN state.
VSS	Ground Reference	Primary return path for all I/O and core logic; requires low-impedance connection to system ground plane to maintain noise immunity during SPI bursts.
SI	Serial Data Input	Accepts instructions, addresses, and write data on rising edge of SCK; sampled once per clock cycle with setup/hold timing dependent on VCC level.
SCK	Serial Clock Input	Master-generated clock synchronizing all data transfers; supports variable frequency up to 10 MHz depending on supply voltage.
HOLD	Hold Input	Pauses ongoing SPI transaction without resetting state machine; must be driven low while SCK is low to avoid metastability; tri-states SO immediately.
VCC	Supply Voltage	Power input for core logic and I/O buffers; decoupling capacitor (0.1 µF ceramic) required within 10 mm of pin to suppress switching noise during write cycles.

Key Features

Feature	Design Value
Self-timed write cycle	≤5 ms internal erase/write completion - eliminates need for external timeout logic; WIP bit in STATUS register enables polling-based synchronization.
Block write protection	Configurable via BP0/BP1 bits to protect none, upper 1/4 (0x6000–0x7FFF), upper 1/2 (0x4000–0x7FFF), or full array - prevents accidental overwrites of critical boot or calibration sectors.
HOLD functionality	Bus pause/resume capability without retransmission - allows host MCU to service higher-priority interrupts mid-transaction while preserving address pointer and command state.
Low-power standby	1 µA max ICCS at 5.5V and 85°C - enables always-on configuration storage in battery-backed systems with multi-year shelf life.
ESD robustness	4 kV HBM rating on all pins - meets industrial IEC 61000-4-2 Level 2 requirements for reliable operation in noisy factory environments.

Applications

Industrial Sensor Calibration Storage	Medical Device Configuration Memory
Use Scenario: Storing factory-calibrated sensor offset/gain coefficients and linearization tables in programmable logic controllers and distributed I/O modules. IC Role / Device Role / Timing Role: Nonvolatile configuration store accessed during power-up initialization and runtime recalibration routines via SPI. Use Value: Guarantees consistent measurement accuracy across product lifetime using 1M-cycle endurance and >200-year data retention under thermal cycling.	Use Scenario: Holding user-defined therapy parameters, device serial numbers, and regulatory compliance logs in portable infusion pumps and diagnostic monitors. IC Role / Device Role / Timing Role: Secure, tamper-resistant memory for FDA-required audit trails and safety-critical settings with hardware write protection. Use Value: WP pin + BP bits prevent unauthorized modification of treatment profiles; RoHS/AEC-Q100 qualification ensures suitability for medical-grade assemblies.
Automotive Body Control Module	Smart Energy Meter Firmware Parameters
Use Scenario: Saving seat/mirror position presets, lighting profiles, and door lock configurations in vehicle BCMs operating across –40°C to +85°C ambient. IC Role / Device Role / Timing Role: SPI-connected persistent memory interfaced directly with 8-bit/16-bit automotive MCUs (e.g., PIC18F, S12X). Use Value: Industrial temp grade and AEC-Q100 qualification ensure reliability in under-hood and cabin-mounted ECUs; HOLD pin enables deterministic interrupt handling.	Use Scenario: Storing tariff schedules, demand-response thresholds, and metrology calibration constants in ANSI C12.20-compliant smart meters deployed outdoors. IC Role / Device Role / Timing Role: Low-power, long-retention memory for infrequently updated utility billing parameters accessed during meter boot or firmware updates. Use Value: 1 µA standby current extends battery backup life; 2.5V min VCC supports brown-out operation during grid instability events.

Industrial Sensor Calibration Storage

Medical Device Configuration Memory

Use Scenario: Storing factory-calibrated sensor offset/gain coefficients and linearization tables in programmable logic controllers and distributed I/O modules.

IC Role / Device Role / Timing Role: Nonvolatile configuration store accessed during power-up initialization and runtime recalibration routines via SPI.

Use Value: Guarantees consistent measurement accuracy across product lifetime using 1M-cycle endurance and >200-year data retention under thermal cycling.

Use Scenario: Holding user-defined therapy parameters, device serial numbers, and regulatory compliance logs in portable infusion pumps and diagnostic monitors.

IC Role / Device Role / Timing Role: Secure, tamper-resistant memory for FDA-required audit trails and safety-critical settings with hardware write protection.

Use Value: WP pin + BP bits prevent unauthorized modification of treatment profiles; RoHS/AEC-Q100 qualification ensures suitability for medical-grade assemblies.

Automotive Body Control Module

Smart Energy Meter Firmware Parameters

Use Scenario: Saving seat/mirror position presets, lighting profiles, and door lock configurations in vehicle BCMs operating across –40°C to +85°C ambient.

IC Role / Device Role / Timing Role: SPI-connected persistent memory interfaced directly with 8-bit/16-bit automotive MCUs (e.g., PIC18F, S12X).

Use Value: Industrial temp grade and AEC-Q100 qualification ensure reliability in under-hood and cabin-mounted ECUs; HOLD pin enables deterministic interrupt handling.

Use Scenario: Storing tariff schedules, demand-response thresholds, and metrology calibration constants in ANSI C12.20-compliant smart meters deployed outdoors.

IC Role / Device Role / Timing Role: Low-power, long-retention memory for infrequently updated utility billing parameters accessed during meter boot or firmware updates.

Use Value: 1 µA standby current extends battery backup life; 2.5V min VCC supports brown-out operation during grid instability events.

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	1.8–5.5V supply range; identical pinout and instruction set; lower VCCmin enables 1.8V MCU compatibility.	Preferred where system operates below 2.5V or requires wider voltage margin during brown-out conditions.	Select 25AA256-I/ST only if 1.8V operation is mandatory; otherwise 25LC256-I/ST offers tighter VCCmax tolerance (5.5V vs 5.5V) and identical performance above 2.5V.
AT25DF256A-SSH-T	3V-only supply (2.7–3.6V); quad-SPI capable; 104 MHz max clock; integrated sector protection registers.	Higher bandwidth and density suited for firmware code storage; not drop-in compatible due to voltage and protocol differences.	Choose AT25DF256A-SSH-T only when migrating to faster quad-SPI interfaces or requiring >256Kbit capacity; not suitable as direct replacement for 25LC256-I/ST in existing designs.

Compared with 25AA256-I/ST and AT25DF256A-SSH-T, the 25LC256-I/ST provides optimal balance of industrial temperature support, 2.5V–5.5V flexibility, and proven SPI compatibility for legacy MCU platforms - making it the preferred choice for cost-sensitive, long-lifecycle embedded systems where voltage headroom and pin-level interchangeability are critical.

Availability

25LC256-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration storage, medical device configuration memory, and automotive body control module applications requiring stable component supply and long-term lifecycle assurance.

Supply support for 25LC256-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, mixed-signal, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design, manufacturing, and sales operations.

The 25LC256-I/ST belongs to Microchip's 25XX256 family of SPI Serial EEPROMs, designed specifically for reliable, low-power nonvolatile data storage in space-constrained embedded systems where SPI interface simplicity and industrial-grade reliability are essential.

FAQ

What is the maximum clock frequency supported by the 25LC256-I/ST?

The 25LC256-I/ST supports up to 10 MHz clock frequency when VCC is 4.5V to 5.5V, 5 MHz at 2.5V ≤ VCC < 4.5V, and 3 MHz at 1.8V ≤ VCC < 2.5V. These limits are defined in Table 1-2 AC Characteristics and ensure reliable setup/hold timing across voltage and temperature ranges. The 25LC256-I/ST does not support 10 MHz operation below 4.5V.

Does the 25LC256-I/ST support hardware write protection?

Yes, the 25LC256-I/ST supports hardware write protection via the WP pin in conjunction with the WPEN bit in the STATUS register. When WPEN = 1 and WP = low, writes to nonvolatile STATUS register bits are disabled. This feature remains active even if the write enable latch (WEL) is set, providing a physical layer of protection against accidental firmware corruption.

How many erase/write cycles is the 25LC256-I/ST rated for?

The 25LC256-I/ST is rated for 1,000,000 erase/write cycles per memory location, as specified in Table 1-3 and confirmed by Microchip's Total Endurance™ characterization model. This endurance is guaranteed at 25°C and VCC = 5.5V, with derating applied per application conditions - enabling multi-decade field deployment in infrequently updated storage roles.

What package type does the 25LC256-I/ST use?

The 25LC256-I/ST uses an 8-lead Plastic Thin Shrink Small Outline Package (TSSOP) with 4.4 mm body width (JEDEC MO-153), designated by the "ST" suffix. Its pinout matches standard TSSOP orientation: Pin 1 = CS, Pin 2 = SO, Pin 3 = WP, Pin 4 = VSS, Pin 5 = SI, Pin 6 = SCK, Pin 7 = HOLD, Pin 8 = VCC.

Can the 25LC256-I/ST be used with 1.8V microcontrollers?

No, the 25LC256-I/ST has a minimum supply voltage of 2.5V and is not guaranteed to operate reliably with 1.8V logic levels. For 1.8V systems, Microchip recommends the functionally identical 25AA256-I/ST, which supports 1.8V–5.5V operation and shares the same pinout, instruction set, and timing specifications as the 25LC256-I/ST.

25LC256-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

25LC256-I/ST FAQ

1.How can I place an order for 25LC256-I/ST through Aetrix?

Please submit a Request for Quotation (RFQ) for 25LC256-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 25LC256-I/ST reliable?

The price and inventory of 25LC256-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 25LC256-I/ST is usually 5 days.

3.What payment methods are accepted for 25LC256-I/ST?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC256-I/ST transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 25LC256-I/ST?

25LC256-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 25LC256-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 25LC256-I/ST?

For technical support, including 25LC256-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC256-I/ST requirements.

6.How does Aetrix verify that 25LC256-I/ST is sourced from the original manufacturer or authorized distributors?

All 25LC256-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 25LC256-I/ST meets industry standards.

7.What is the process for return or replacement of 25LC256-I/ST?

All 25LC256-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC256-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 25LC256-I/ST part is unused and in its original packaging.

Return procedure for 25LC256-I/ST:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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