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Microchip Technology 25LC256XT-E/ST

Name: 25LC256XT-E/ST
Brand: Microchip Technology
SKU: 25LC256XT-E/ST
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 25LC256XT-E/ST

Manufacturer:: Microchip Technology

Category:: Memory

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

Datasheet:: 25LC256XT-E/ST.pdf

Description:: IC EEPROM 256KBIT SPI 8TSSOP

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Product details

Overview

25LC256XT-E/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 operation (−40°C to +85°C). It features hardware write protection via WP pin and STATUS register, self-timed 5 ms write cycles, and 1 µA standby current - deployed in embedded systems for firmware parameter storage, calibration data retention, and configuration backup.

For engineers reviewing the 25LC256XT-E/ST datasheet, 25LC256XT-E/ST pinout, 25LC256XT-E/ST application, or 25LC256XT-E/ST equivalent, key selection criteria include VCC range (2.5–5.5V), SPI Mode 0/1 compatibility, HOLD functionality for interrupt-safe bus arbitration, and AEC-Q100 qualification for automotive-grade reliability.

Technical Context

The 25LC256XT-E/ST implements a standard SPI interface with separate SI/SO lines, CS-controlled device selection, and HOLD input for pausing ongoing transfers without sequence reset. Its internal architecture includes an 8-bit instruction register, page latches, and high-voltage generator for EEPROM programming.

It supports four block protection levels (none, 1/4, 1/2, or full array) via BP0/BP1 bits in the nonvolatile STATUS register, and integrates power-on write-disable, WREN/WRDI command sequencing, and WIP bit polling for write cycle status monitoring - all compliant with JEDEC-standard SPI timing at up to 10 MHz under 5.5V supply.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	256 Kbit (32,768 × 8) organized as 32K bytes - sufficient for storing bootloader configs, sensor calibration tables, or device identity data in space-constrained designs.
Interface	SPI-compatible serial bus (Mode 0,0 and Mode 1,1) with dedicated SI, SO, SCK, CS, HOLD, and WP pins - enables direct connection to MCU SPI peripherals without level-shifting or protocol translation.
Page Size	64-byte page buffer - allows burst writes up to 64 bytes within same physical page boundary; crossing page boundaries wraps data instead of advancing, requiring software address alignment.
Write Cycle Time	Max 5 ms internal self-timed erase/write - eliminates need for external timing control; WIP bit in STATUS register enables polling-based completion detection.
Supply Voltage	2.5V to 5.5V operating range - supports mixed-voltage systems including 3.3V logic domains and legacy 5V microcontrollers without external regulators.
Endurance & Retention	1,000,000 erase/write cycles and >200 years data retention - validated for long-life applications such as industrial controllers, automotive ECUs, and medical devices with infrequent but critical updates.
Temperature Range	Industrial grade: −40°C to +85°C - qualified per AEC-Q100 Grade 3, enabling use in under-hood automotive modules and outdoor industrial gateways.

Pinout & Package

25LC256XT-E/ST is housed in an 8-lead TSSOP package (4.4 mm body width, JEDEC MO-153), marked "25LC256I" with temperature code 'I' and RoHS-compliant matte tin finish. Pin 1 is located at the top-left corner with notch or dot marking.

Pin/Terminal	Circuit Role	Design Meaning
CS	Chip Select Input	Active-low enable signal; must be low for instruction/address/data transfer; rising edge initiates internal write cycle after valid WRITE sequence.
SO	Serial Data Output	Tri-state output delivering read data 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 writes when WPEN bit = 1; low = protection enabled; no effect on memory array writes unless BP bits are set.
VSS	Ground Reference	Primary return path for all internal circuitry and I/O; requires low-impedance connection to system ground plane.
SI	Serial Data Input	Input for instructions, addresses, and write data; sampled on rising edge of SCK; ignored during HOLD assertion.
SCK	Serial Clock Input	Master-generated clock synchronizing all SPI transfers; rising edge latches SI, falling edge updates SO; max 10 MHz at VCC ≥ 4.5V.
HOLD	Hold Input	Pauses ongoing SPI transaction when pulled low while SCK is low; preserves internal state for resumption without retransmission - critical for real-time interrupt handling.
VCC	Supply Voltage	Power input for core logic and EEPROM array; bypass capacitor (0.1 µF ceramic) required near pin for noise suppression during write cycles.

Key Features

Feature	Design Value
Block Write Protection	Selectable protection of none, upper 1/4 (6000h–7FFFh), upper 1/2 (4000h–7FFFh), or full array (0000h–7FFFh) via BP0/BP1 bits - prevents accidental overwrites of critical firmware or calibration sectors.
Built-in Power-On Write Protection	Write enable latch resets automatically at power-up, and WEL bit clears after every successful WRITE/WRSR/WRDI - eliminating risk of spurious writes during brown-out or reset conditions.
HOLD Functionality	Enables deterministic pause/resume of multi-byte SPI transfers without losing byte count or address pointer state - essential for deterministic latency in safety-critical or time-bounded systems.
Low-Power Operation	1 µA standby current at 5.5V/125°C and 6 mA active read current at 5.5V/10 MHz - extends battery life in portable instrumentation and reduces thermal load in dense PCB layouts.
AEC-Q100 Qualification	Qualified to Automotive Electronics Council standard Grade 3 (−40°C to +85°C), including stress testing for temperature cycling, HTOL, and ESD (>4 kV HBM) - suitable for Tier-1 automotive subsystems without additional qualification effort.

Applications

Automotive Body Control Module	Industrial PLC Configuration Storage
Use Scenario: Storing door lock logic states, mirror position presets, and lighting profiles across ignition cycles in a vehicle body controller. IC Role / Device Role / Timing Role: Nonvolatile configuration register holding user-defined settings; accessed via SPI during boot and updated only on explicit request. Use Value: Enables persistent personalization without external battery backup; AEC-Q100 qualification ensures reliability over 15-year vehicle lifetime.	Use Scenario: Retaining I/O mapping tables, PID tuning parameters, and alarm thresholds in programmable logic controllers used in factory automation. IC Role / Device Role / Timing Role: Dedicated configuration EEPROM interfaced to ARM Cortex-M7 host MCU via hardware SPI peripheral. Use Value: Survives frequent power cycling and field firmware updates; 1M endurance supports decades of parameter adjustments in unattended deployments.
Medical Infusion Pump Calibration	Smart Energy Meter Firmware Patch Storage
Use Scenario: Holding flow-rate calibration coefficients and motor compensation curves that must survive sterilization cycles and battery replacement. IC Role / Device Role / Timing Role: SPI-connected data vault storing factory-trimmed analog front-end parameters; read once per power-on, write only during service mode. Use Value: >200-year data retention guarantees accuracy over product lifecycle; ESD-hardened design withstands clinical environment handling.	Use Scenario: Storing signed firmware patches and cryptographic keys for secure over-the-air updates in utility-grade electricity meters. IC Role / Device Role / Timing Role: Secure boot adjunct storing verified update metadata; accessed only by trusted execution environment during OTA validation. Use Value: Hardware write-protection (WP + BP bits) prevents tampering with patch integrity flags; 2.5–5.5V range matches meter's wide-input DC-DC output.

Automotive Body Control Module

Industrial PLC Configuration Storage

Use Scenario: Storing door lock logic states, mirror position presets, and lighting profiles across ignition cycles in a vehicle body controller.

IC Role / Device Role / Timing Role: Nonvolatile configuration register holding user-defined settings; accessed via SPI during boot and updated only on explicit request.

Use Value: Enables persistent personalization without external battery backup; AEC-Q100 qualification ensures reliability over 15-year vehicle lifetime.

Use Scenario: Retaining I/O mapping tables, PID tuning parameters, and alarm thresholds in programmable logic controllers used in factory automation.

IC Role / Device Role / Timing Role: Dedicated configuration EEPROM interfaced to ARM Cortex-M7 host MCU via hardware SPI peripheral.

Use Value: Survives frequent power cycling and field firmware updates; 1M endurance supports decades of parameter adjustments in unattended deployments.

Medical Infusion Pump Calibration

Smart Energy Meter Firmware Patch Storage

Use Scenario: Holding flow-rate calibration coefficients and motor compensation curves that must survive sterilization cycles and battery replacement.

IC Role / Device Role / Timing Role: SPI-connected data vault storing factory-trimmed analog front-end parameters; read once per power-on, write only during service mode.

Use Value: >200-year data retention guarantees accuracy over product lifecycle; ESD-hardened design withstands clinical environment handling.

Use Scenario: Storing signed firmware patches and cryptographic keys for secure over-the-air updates in utility-grade electricity meters.

IC Role / Device Role / Timing Role: Secure boot adjunct storing verified update metadata; accessed only by trusted execution environment during OTA validation.

Use Value: Hardware write-protection (WP + BP bits) prevents tampering with patch integrity flags; 2.5–5.5V range matches meter's wide-input DC-DC output.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Serial EEPROM applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
AT25SF256B-SSHD-B	Quad SPI interface, 133 MHz max clock, 32 Mbit density, 1.7–2.0V VCC range - not pin-compatible; requires different driver stack.	Targeted at high-speed boot code storage in flash-like applications; lacks HOLD pin and hardware WP pin.	Select only if migrating to QSPI infrastructure and needing faster sequential reads; not drop-in for existing 25LC256XT-E/ST designs.
BR25H256FJ-WE2	Same 256 Kbit SPI EEPROM, 2.5–5.5V, 10 MHz, 64-byte page, but with built-in error correction (ECC) and extended −40°C to +125°C rating (E grade).	Designed for functional-safety systems requiring single-bit error detection/correction; higher temp grade suits under-hood engine control units.	Prefer when ECC is mandated by ISO 26262 ASIL-B or when operating beyond +85°C ambient; otherwise identical usage model.

Compared with AT25SF256B-SSHD-B and BR25H256FJ-WE2, the 25LC256XT-E/ST offers proven industrial-grade reliability with HOLD and WP pin support at lower cost, making it optimal for cost-sensitive, interrupt-aware embedded systems where QSPI speed or ECC are unnecessary.

Availability

25LC256XT-E/ST is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC configuration storage, medical infusion pump calibration, and smart energy meter firmware patch storage requiring stable component supply and long-term lifecycle support.

Supply support for 25LC256XT-E/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 and manufacturing operations.

The 25LC256XT-E/ST belongs to Microchip's 25XX256 family of SPI Serial EEPROMs, engineered for robust, low-power nonvolatile data storage in automotive, industrial, and medical systems where deterministic timing, hardware write protection, and long-term data integrity are mandatory.

FAQ

What is the maximum clock frequency supported by the 25LC256XT-E/ST?

The 25LC256XT-E/ST supports a maximum SPI clock frequency of 10 MHz when VCC is 4.5V to 5.5V. At 2.5V ≤ VCC < 4.5V, the limit drops to 5 MHz, and at 1.8V ≤ VCC < 2.5V, it is 3 MHz. These limits ensure reliable setup/hold timing across voltage and temperature ranges - critical for maintaining data integrity in the 25LC256XT-E/ST's internal shift registers and EEPROM array.

Does the 25LC256XT-E/ST require external pull-up resistors on its SPI lines?

No, the 25LC256XT-E/ST does not require external pull-ups on SI, SO, or SCK. Its inputs (CS, WP, HOLD, SI) have internal weak pull-downs or are CMOS-compatible with rail-to-rail logic levels. SO is actively driven or tri-stated - never open-drain - so external pull-ups would cause contention. Only CS may benefit from a weak external pull-up in noisy environments to ensure clean deassertion, but it is not mandatory for correct 25LC256XT-E/ST operation.

How does the HOLD function behave during an active write cycle in the 25LC256XT-E/ST?

The HOLD pin has no effect during an internal write cycle (TWC) in the 25LC256XT-E/ST. Once CS rises after a valid WRITE sequence, the device enters self-timed programming mode, and all inputs - including HOLD - are ignored until the 5 ms cycle completes. HOLD only pauses ongoing SPI communication (read/write instructions, address, data) before CS deassertion; it cannot interrupt or suspend active EEPROM programming.

Can the 25LC256XT-E/ST be used with 1.8V microcontrollers?

No, the 25LC256XT-E/ST is not rated for 1.8V operation. Its minimum VCC is 2.5V, as specified in the Device Selection Table and DC Characteristics. While the related 25AA256 variant supports 1.8V, the 25LC256XT-E/ST requires 2.5–5.5V. Using it below 2.5V risks unreliable instruction decoding, incomplete writes, or STATUS register corruption - invalidating all 25LC256XT-E/ST functionality.

What package type does the 'ST' suffix indicate for the 25LC256XT-E/ST?

The 'ST' suffix in 25LC256XT-E/ST denotes the 8-lead Plastic Thin Shrink Small Outline (TSSOP) package with 4.4 mm body width, per JEDEC MO-153. This surface-mount package features gull-wing leads, pin 1 indicator notch, and RoHS-compliant matte tin plating - optimized for automated assembly and high-density PCB layouts where SOIC (SN) or PDIP (P) footprints are too large.

25LC256XT-E/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:: 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 ~ 125°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-TSSOP

25LC256XT-E/ST FAQ

1.How can I place an order for 25LC256XT-E/ST through Aetrix?

Please submit a Request for Quotation (RFQ) for 25LC256XT-E/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 25LC256XT-E/ST reliable?

The price and inventory of 25LC256XT-E/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC256XT-E/ST is usually 5 days.

3.What payment methods are accepted for 25LC256XT-E/ST?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC256XT-E/ST transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 25LC256XT-E/ST?

25LC256XT-E/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 25LC256XT-E/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 25LC256XT-E/ST?

For technical support, including 25LC256XT-E/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC256XT-E/ST requirements.

6.How does Aetrix verify that 25LC256XT-E/ST is sourced from the original manufacturer or authorized distributors?

All 25LC256XT-E/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 25LC256XT-E/ST meets industry standards.

7.What is the process for return or replacement of 25LC256XT-E/ST?

All 25LC256XT-E/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC256XT-E/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 25LC256XT-E/ST part is unused and in its original packaging.

Return procedure for 25LC256XT-E/ST:

1.Submit a request within 90 days.

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

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