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Microchip Technology 25LC256T-E/SM
- Part No.:
- 25LC256T-E/SM
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
25LC256T-E/SM.pdf
- Description:
- IC EEPROM 256KBIT SPI 8SOIJ
- Quantity:
- Payment:
- Shipping:
Inventory:1,868
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Product details
Overview
25LC256T-E/SM from Microchip Technology Inc. is a 256 Kbit SPI Serial EEPROM with 32,768 × 8-bit organization, 64-byte page size, and industrial-grade operation (−40°C to +85°C). It supports up to 10 MHz clock frequency, features hardware write protection via WP pin and STATUS register, and delivers 1,000,000 erase/write cycles with >200-year data retention - used for firmware storage, calibration data logging, and configuration backup in embedded control systems.
For engineers reviewing the 25LC256T-E/SM datasheet, 25LC256T-E/SM pinout, 25LC256T-E/SM application, or 25LC256T-E/SM equivalent, key selection criteria include VCC range (2.5–5.5V), HOLD/CS/SO/SI/SCK/WP/VSS/VCC 8-pin SOIC-SM package compatibility, self-timed 5 ms max write cycle, and block-level write protection granularity (none/¼/½/all array).
Technical Context
The 25LC256T-E/SM implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (data-in) and SO (data-out) lines, requiring CS assertion and SCK synchronization. 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, and WPEN bits.
Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate internal 5 ms write cycle; page writes are limited to 64-byte boundaries without wrap-around across pages. HOLD pin enables mid-sequence suspension while preserving state, and WP pin combined with WPEN bit enables hardware-level nonvolatile status register lockout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8-bit), directly addressable via 16-bit SPI command addressing |
| Interface | SPI-compatible serial bus (Mode 0,0 or 1,1), with dedicated SI/SO lines and CS/SCK control |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5V - enables fast read/write throughput in high-speed microcontroller systems |
| Page Size | 64 bytes - constrains burst writes to single-page boundaries; crossing boundary wraps data within page |
| Write Cycle Time | 5 ms max self-timed internal 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 deployment |
| VCC Range | 2.5V to 5.5V - supports dual-supply designs and brown-out tolerant operation in 3.3V/5V systems |
Pinout & Package
25LC256T-E/SM is housed in an 8-lead SOIC package with 3.90 mm body width (JEDEC MS-012AA), marked "25LC256T-E/SM" and RoHS-compliant matte tin finish. Pin 1 is located at the top-left corner with notch or dot indicator.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable; must be low for all SPI transactions; rising edge initiates internal write cycle |
| SO | Serial Data Output | Tri-state output; data shifted out on falling edge of SCK during READ; high-Z when CS high or HOLD active |
| WP | Write-Protect Input | Hardware lock for STATUS register when WPEN=1; no effect on memory writes unless configured in STATUS |
| VSS | Ground Reference | Primary return path for all internal circuitry and I/O; must be connected to system GND plane |
| SI | Serial Data Input | Data, instructions, and addresses latched on rising edge of SCK; MSB-first protocol |
| SCK | Serial Clock Input | Master-generated clock; defines timing for SI sampling and SO update; requires stable duty cycle |
| HOLD | Serial Bus Hold Input | Pauses ongoing SPI sequence when pulled low during SCK low; preserves internal state for resume |
| VCC | Supply Voltage | Power input (2.5–5.5V); powers EEPROM core, logic, and charge pump; bypass capacitor required |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Selective protection of none / 1/4 / 1/2 / full memory array via BP0/BP1 bits - prevents accidental firmware corruption |
| Power-On Write Protection | Automatic WEL reset at power-up and after each WRITE/WRSR - eliminates spurious writes during supply ramp |
| HOLD Functionality | Mid-transaction pause without reinitialization - enables interrupt servicing in real-time microcontroller hosts |
| Low Standby Current | 1 µA typical at 5.5V - critical for battery-backed systems and energy-constrained IoT nodes |
| ESD Robustness | 4 kV HBM rating on all pins - ensures reliability in handling and board assembly environments |
Applications
| Industrial PLC Configuration Storage | Automotive ECU Calibration Data Logging |
|---|---|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and fault history in programmable logic controllers with frequent field updates. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via SPI during boot and runtime parameter adjustment. Use Value: 64-byte page writes enable efficient partial updates; 1M endurance supports decades of maintenance cycles. |
Use Scenario: Recording sensor calibration offsets, trim values, and adaptive learning data in engine control units operating across −40°C to +125°C. IC Role / Device Role / Timing Role: AEC-Q100 qualified EEPROM providing tamper-resistant storage for safety-critical calibration constants. Use Value: Hardware WP pin + STATUS register lock prevents unauthorized modification; >200-year retention ensures lifetime data integrity. |
| Medical Device Setup Profiles | Smart Meter Firmware Patch Storage |
Use Scenario: Saving user-defined therapy modes, alarm thresholds, and device preferences in portable diagnostic equipment. IC Role / Device Role / Timing Role: Secure, low-power SPI EEPROM interfaced to ARM Cortex-M host for persistent settings retention. Use Value: 1 µA standby current extends battery life; sequential read simplifies profile loading during power-on initialization. |
Use Scenario: Holding over-the-air firmware patches and cryptographic keys in utility meters deployed in remote locations. IC Role / Device Role / Timing Role: Trusted nonvolatile memory for secure code storage with hardware write protection against malicious overwrite. Use Value: Block protection allows locking bootloader region while permitting patch updates to application section. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA256-I/SM | Wider VCC range (1.8–5.5V); identical pinout, timing, and memory map | Better suited for 1.8V/2.5V logic systems; not rated for extended temperature | Select 25AA256-I/SM only if supply voltage may drop below 2.5V and industrial temp suffices |
| AT25DF256A-SSH-T | Dual/quad SPI interface; 32 Mbit density; different command set and sector protection model | Requires firmware adaptation; supports faster bulk reads but lacks HOLD pin and same page-write behavior | Choose AT25DF256A-SSH-T only when higher density or quad-mode speed is mandatory and layout changes acceptable |
Compared with 25LC256T-E/SM, 25AA256-I/SM offers lower-voltage flexibility but reduced thermal margin, while AT25DF256A-SSH-T provides greater capacity and speed at the cost of command compatibility and pin-level interoperability.
Availability
25LC256T-E/SM is available at Aetrix Electronics and suitable for industrial PLCs, automotive ECUs, medical devices, and smart metering systems requiring stable component supply, long-term lifecycle support, and AEC-Q100 compliance.
Supply support for 25LC256T-E/SM 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 infrastructure.
The 25LC256T-E/SM belongs to Microchip's legacy 25XX256 SPI EEPROM family, designed for reliable, low-power, pin-compatible nonvolatile storage in cost-sensitive industrial and automotive applications.
FAQ
What is the operating temperature range for the 25LC256T-E/SM?
The 25LC256T-E/SM is rated for the Industrial temperature range of −40°C to +85°C. This is confirmed in the Device Selection Table and Electrical Characteristics section of the official datasheet DS20001822H. The "E" suffix in the part number denotes Extended temperature grade, but the specific 25LC256T-E/SM variant uses the Industrial (I) qualification level per package marking and specification tables.
Does the 25LC256T-E/SM support SPI Mode 3,0 (CPOL=1, CPHA=0)?
No, the 25LC256T-E/SM supports only SPI Mode 0,0 (CPOL=0, CPHA=0) and Mode 1,1 (CPOL=1, CPHA=1), as explicitly defined in Figure 1-2 and Figure 1-3 of the datasheet. Attempting Mode 3,0 will result in incorrect data sampling because SI is latched on the rising edge of SCK and SO is updated after the falling edge - incompatible with Mode 3,0 timing requirements.
How does the HOLD pin function during an active write cycle in the 25LC256T-E/SM?
The HOLD pin has no effect during an active internal write cycle (TWC) in the 25LC256T-E/SM. As stated in Section 3.6, HOLD suspends serial communication only when the device is selected and actively receiving or transmitting data. Once CS rises to initiate TWC, the device ignores HOLD transitions until the write completes and returns to standby mode.
Can the 25LC256T-E/SM be used with a 1.8V microcontroller SPI interface?
No - the 25LC256T-E/SM requires a minimum VCC of 2.5V and specifies DC and AC characteristics only down to that level. Its VIH threshold is 0.7×VCC (min 1.75V at 2.5V), but the device is not characterized or guaranteed for reliable operation below 2.5V. For 1.8V systems, the 25AA256-I/SM variant is the appropriate choice.
What happens if a page write crosses a 64-byte boundary in the 25LC256T-E/SM?
If a page write command attempts to cross a 64-byte boundary, data wraps around to the start of the same physical page instead of advancing to the next page. This behavior is explicitly documented in Section 2.3 and results in unintended overwrites of earlier bytes in the page. Application firmware must enforce address alignment and byte count limits to prevent this condition.
25LC256T-E/SM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- 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-SOIJ
25LC256T-E/SM FAQ
1.How can I place an order for 25LC256T-E/SM through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC256T-E/SM 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 25LC256T-E/SM reliable?
The price and inventory of 25LC256T-E/SM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC256T-E/SM is usually 5 days.
3.What payment methods are accepted for 25LC256T-E/SM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC256T-E/SM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC256T-E/SM?
25LC256T-E/SM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC256T-E/SM 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 25LC256T-E/SM?
For technical support, including 25LC256T-E/SM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC256T-E/SM requirements.
6.How does Aetrix verify that 25LC256T-E/SM is sourced from the original manufacturer or authorized distributors?
All 25LC256T-E/SM 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 25LC256T-E/SM meets industry standards.
7.What is the process for return or replacement of 25LC256T-E/SM?
All 25LC256T-E/SM units undergo pre-shipment inspection (PSI). If there is an issue with 25LC256T-E/SM, 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 25LC256T-E/SM part is unused and in its original packaging.
Return procedure for 25LC256T-E/SM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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