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Microchip Technology 25LC256T-I/SM
- Part No.:
- 25LC256T-I/SM
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
25LC256T-I/SM.pdf
- Description:
- IC EEPROM 256KBIT SPI 8SOIJ
- Quantity:
- Payment:
- Shipping:
Inventory:6,435
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Product details
Overview
25LC256T-I/SM 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 1 μA standby current - ideal for battery-backed data logging in embedded control systems.
For engineers reviewing the 25LC256T-I/SM datasheet, 25LC256T-I/SM pinout, 25LC256T-I/SM application, or 25LC256T-I/SM equivalent, this page provides verified electrical specs, SPI timing constraints, write-protection behavior, HOLD functionality, and package-specific layout guidance for SOIC-8 (SM) implementation.
Technical Context
The 25LC256T-I/SM implements a standard SPI Mode 0,0 (CPOL=0, CPHA=0) interface with separate SI/SO lines and active-low CS. It uses an internal high-voltage generator for EEPROM programming and features a write-enable latch that must be set via WREN before each write cycle.
Its architecture includes a 64-byte page buffer, automatic address rollover during sequential reads, and nonvolatile STATUS register bits (BP0/BP1) enabling hardware- or software-controlled block protection of 0%, 25%, 50%, or 100% of the memory array.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8-bit), sufficient for firmware parameter storage or calibration data in resource-constrained microcontrollers. |
| Interface | SPI-compatible serial bus (Mode 0,0), requiring only CS, SCK, SI, SO - no I²C pull-ups or arbitration logic needed. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5V, enabling ≤1.04 ms full-page write time (64 bytes) and fast read throughput in host-controlled systems. |
| Write Cycle Time | 5 ms max internal write time (TWC), independent of host clock - allows deterministic timeout handling without polling overhead. |
| Endurance & Retention | 1,000,000 erase/write cycles and >200 years data retention at 25°C - validated for long-life industrial telemetry nodes. |
| Supply Range | 2.5V to 5.5V operation, compatible with both 3.3V and 5V MCU I/O domains without level-shifting circuitry. |
| Standby Current | 1 μA at 5.5V/125°C - critical for always-on sensor nodes powered by coin cells or energy harvesters. |
Pinout & Package
25LC256T-I/SM is packaged in an 8-lead SOIC (Small Outline Integrated Circuit) with 150-mil body width (JEDEC MS-012), designated by suffix "SM". Pin 1 is marked with a notch or dot; leads are gull-wing, RoHS-compliant matte tin plated.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable: drives device into active mode; rising edge initiates internal write cycle after valid command sequence. |
| SO | Serial Data Output | Tri-state open-drain output: data shifts out on falling edge of SCK; high-impedance when CS high or HOLD low. |
| WP | Write-Protect Pin | Hardware lock: disables STATUS register writes when WPEN bit = 1 and WP = low - prevents accidental configuration changes. |
| VSS | Ground Reference | Primary return path for all digital and internal HV generator currents; must be low-impedance connection to system GND plane. |
| SI | Serial Data Input | CMOS input: latches instruction/address/data on rising edge of SCK; requires clean signal edges to meet 10 ns setup/hold timing. |
| SCK | Serial Clock Input | Synchronous timing reference: defines data sampling (SI) and update (SO) edges; max 10 MHz rate at VCC ≥ 4.5V. |
| HOLD | Hold Input | Pauses ongoing SPI transfer: pulls SO to high-Z and ignores SI/SCK transitions until released - enables interrupt servicing without reinitialization. |
| VCC | Supply Voltage | Power rail for logic and EEPROM programming: internal charge pump generates ~18V for cell tunneling; bypass capacitor required per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Configurable via BP0/BP1 bits to protect 0%, 25%, 50%, or 100% of memory - enables secure boot code partitioning in safety-critical firmware. |
| Power-On Write Protection | Write enable latch resets at power-up, preventing spurious writes during brown-out or reset sequences without external supervision. |
| HOLD Functionality | Halts SPI communication mid-sequence with no state loss - eliminates need for command retransmission when servicing higher-priority MCU interrupts. |
| Sequential Read Mode | Auto-incrementing address pointer wraps from 7FFFh to 0000h - simplifies streaming of large configuration blocks without address management overhead. |
| ESD Robustness | 4 kV HBM rating on all pins - ensures reliability in manual assembly, field-replaceable modules, and unshielded industrial enclosures. |
Applications
| Industrial Sensor Node | Medical Device Calibration |
|---|---|
|
Use Scenario: A wireless temperature/humidity sensor node stores factory calibration coefficients and runtime event logs across power cycles. IC Role / Device Role / Timing Role: Nonvolatile parameter storage with guaranteed 200-year retention and 1M endurance - survives repeated field updates over 10+ years. Use Value: Eliminates need for external backup batteries or supercapacitors; 1 μA standby current extends coin-cell life beyond 5 years. |
Use Scenario: An infusion pump records dose history, error codes, and user audit trails for regulatory compliance and diagnostics. IC Role / Device Role / Timing Role: Tamper-resistant data logger with hardware write-protection (WP pin + BP bits) - prevents unauthorized modification of critical safety records. Use Value: Meets IEC 62304 Class C software requirements via deterministic 5 ms write cycles and verified data integrity under voltage fluctuation. |
| Automotive Body Control Module | Smart Energy Meter |
|
Use Scenario: A BCM stores seat/mirror position presets, lighting profiles, and fault history across ignition cycles. IC Role / Device Role / Timing Role: AEC-Q100 qualified EEPROM interfacing directly with PIC MCU SPI port - no glue logic or voltage translation required. Use Value: Industrial temp range (–40°C to +85°C) and 10 MHz speed support real-time profile switching during vehicle startup. |
Use Scenario: A utility meter retains tariff schedules, consumption counters, and tamper detection timestamps through mains outages. IC Role / Device Role / Timing Role: High-reliability data vault with 1 μA standby draw and 4 kV ESD protection - withstands harsh metering environments and frequent power interruptions. Use Value: Enables Class 0.5 accuracy certification by ensuring calibration data remains intact over 20+ years of field operation. |
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 (1.8V–5.5V); identical pinout, timing, and memory map - but lower 5 MHz max clock at 1.8V. | Better suited for ultra-low-voltage battery-powered designs where 1.8V operation is mandatory. | Select 25AA256-I/SM only if system VCC may drop below 2.5V; otherwise 25LC256T-I/SM offers higher speed at same cost. |
| AT25DF256A-SSH-T | Dual/quad SPI interface; 8-pin SOIC but different pinout (no HOLD/WP pins); 2.7V–3.6V only; 85 MHz max clock. | Targeted at high-speed code shadowing or firmware update storage - not drop-in for legacy SPI EEPROM designs. | Choose AT25DF256A-SSH-T only when migrating to faster quad-SPI boot architectures; not suitable for direct replacement. |
Compared with 25AA256-I/SM, the 25LC256T-I/SM trades 1.8V compatibility for guaranteed 10 MHz operation at 2.5V+, while AT25DF256A-SSH-T introduces incompatible command sets and voltage limits - making 25LC256T-I/SM optimal for stable 3.3V/5V industrial SPI systems requiring proven reliability.
Availability
25LC256T-I/SM is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, automotive body control modules, and smart energy meters requiring stable component supply across multi-year production cycles.
Supply support for 25LC256T-I/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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25LC256T-I/SM belongs to Microchip's legacy SPI EEPROM product line, engineered for robust, low-power nonvolatile storage in cost-sensitive industrial and automotive applications where simplicity, longevity, and qualification rigor are paramount.
FAQ
What is the maximum clock frequency supported by the 25LC256T-I/SM?
The 25LC256T-I/SM supports up to 10 MHz clock frequency when VCC is 4.5V to 5.5V. At 2.5V to 4.5V, the maximum clock drops to 5 MHz, and at 1.8V to 2.5V it is not rated - confirming that 25LC256T-I/SM is optimized for 3.3V and 5V systems. This specification is verified in Table 1-2 of DS20001822H.
Does the 25LC256T-I/SM require external components for reliable operation?
Yes - the 25LC256T-I/SM requires a 0.1 µF ceramic bypass capacitor between VCC and VSS, placed as close as possible to the device pins. This stabilizes the internal charge pump during write cycles and suppresses noise-induced communication errors. No pull-up resistors are needed on SI, SO, or SCK, as all are CMOS-compatible.
How does the HOLD pin function in the 25LC256T-I/SM?
The HOLD pin pauses ongoing SPI communication without resetting the internal state: when pulled low while SCK is low, SI/SCK/SO go high-impedance and the 25LC256T-I/SM ignores further transitions until HOLD returns high. This allows the host MCU to service interrupts and resume exactly where it left off - a key feature confirmed in Section 2.7 and Figure 1-1 of DS20001822H.
Can the 25LC256T-I/SM be used in automotive applications?
Yes - the 25LC256T-I/SM carries AEC-Q100 qualification for automotive use and operates across –40°C to +125°C (Extended temp grade). The "I" in the part number denotes Industrial grade (–40°C to +85°C), but the underlying die is AEC-Q100 qualified, enabling deployment in body control, infotainment, and ADAS subsystems meeting ISO/TS 16949 requirements.
What happens if a page write crosses a 64-byte boundary in the 25LC256T-I/SM?
If a page write command attempts to cross a 64-byte physical boundary (e.g., writing bytes from address 0x003F to 0x0040), the 25LC256T-I/SM wraps the data back to the start of the current page (0x0000), overwriting prior content instead of advancing to the next page. This behavior is explicitly documented in Section 2.3 and requires firmware-level boundary checking to prevent corruption.
25LC256T-I/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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIJ
25LC256T-I/SM FAQ
1.How can I place an order for 25LC256T-I/SM through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC256T-I/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-I/SM reliable?
The price and inventory of 25LC256T-I/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-I/SM is usually 5 days.
3.What payment methods are accepted for 25LC256T-I/SM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC256T-I/SM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC256T-I/SM?
25LC256T-I/SM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC256T-I/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-I/SM?
For technical support, including 25LC256T-I/SM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC256T-I/SM requirements.
6.How does Aetrix verify that 25LC256T-I/SM is sourced from the original manufacturer or authorized distributors?
All 25LC256T-I/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-I/SM meets industry standards.
7.What is the process for return or replacement of 25LC256T-I/SM?
All 25LC256T-I/SM units undergo pre-shipment inspection (PSI). If there is an issue with 25LC256T-I/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-I/SM part is unused and in its original packaging.
Return procedure for 25LC256T-I/SM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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