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Microchip Technology 25AA256-E/SN
- Part No.:
- 25AA256-E/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25AA256-E/SN.pdf
- Description:
- IC EEPROM 256KBIT SPI 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,017
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Product details
Overview
25AA256-E/SN from Microchip Technology Inc. is a 256 Kbit (32,768 × 8) SPI serial EEPROM with 1.8–5.5 V supply range, 64-byte page write capability, and industrial/extended temperature support (–40°C to +125°C). It features hardware write protection via WP pin and STATUS register, HOLD functionality for interrupt-safe bus suspension, and operates up to 10 MHz at 4.5–5.5 V. It is used in embedded systems for firmware parameter storage, calibration data retention, and configuration backup.
For engineers reviewing the 25AA256-E/SN datasheet, 25AA256-E/SN pinout, 25AA256-E/SN application, or 25AA256-E/SN equivalent, key selection criteria include its 1.8 V minimum VCC, 1 μA standby current, AEC-Q100 qualification for automotive use, and SOIC-8 (SN) package compatibility with standard PCB footprints.
Technical Context
The 25AA256-E/SN implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data in) and SO (data out) lines, requiring CS, SCK, and optional HOLD/WP control. Its internal architecture includes a 64-byte page latch, nonvolatile STATUS register with BP0/BP1 block protection bits, and HV generator for EEPROM cell programming.
Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate TWC (5 ms max), while read supports continuous sequential access with automatic address rollover. The HOLD pin suspends ongoing transfers without resetting the internal state, enabling deterministic interrupt handling in real-time microcontroller systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - provides sufficient space for boot code flags, sensor calibration tables, and device identity storage in resource-constrained MCUs. |
| Interface | SPI-compatible serial bus (Mode 0,0) - enables direct connection to PIC® and other MCU SPI peripherals without glue logic or level shifters. |
| VCC Range | 1.8 V to 5.5 V - supports single-supply operation across battery-powered (1.8–3.3 V) and legacy 5 V industrial systems. |
| Page Size | 64 bytes - constrains burst writes to aligned boundaries; software must manage cross-page writes to avoid data wraparound. |
| Write Cycle Time | 5 ms maximum - defines minimum interval between successive page writes; impacts firmware update latency and logging throughput. |
| Endurance & Retention | 1,000,000 erase/write cycles / >200 years data retention - ensures long-term reliability in infrequently updated configuration storage applications. |
| Temperature Range | –40°C to +125°C (Extended grade) - qualified for under-hood automotive, industrial motor drives, and outdoor IoT edge nodes. |
Pinout & Package
25AA256-E/SN is packaged in an 8-lead narrow SOIC (SN) with 1.27 mm pitch, 3.90 mm body width, and JEDEC MS-012AC compliant footprint. The package supports reflow soldering and is compatible with standard automated assembly processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low enable signal; deselecting places SO in high-impedance state, allowing multi-device SPI bus sharing. |
| SO (Pin 2) | Serial Data Output | Tri-state output delivering read data on falling SCK edge; high-Z when CS high or HOLD active. |
| WP (Pin 3) | Write-Protect Pin | Hardware lock for STATUS register writes when WPEN bit = 1; low = protection enabled, high = full write access. |
| VSS (Pin 4) | Ground Reference | Primary return path for all I/O and core circuitry; requires low-impedance PCB plane connection for noise immunity. |
| SI (Pin 5) | Serial Data Input | Latches instructions, addresses, and write data on rising SCK edge; sampled only when CS is asserted. |
| SCK (Pin 6) | Serial Clock Input | Master-generated clock synchronizing all SPI transactions; max 10 MHz at VCC ≥ 4.5 V. |
| HOLD (Pin 7) | Hold Input | Pauses ongoing SPI transfer (e.g., mid-read) without losing internal state; resumes on HOLD high while SCK low. |
| VCC (Pin 8) | Supply Voltage | Power input for core logic and EEPROM array; bypass capacitor (0.1 µF) required near pin for stable operation. |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Configurable via STATUS register (BP0/BP1) to protect 0%, 25%, 50%, or 100% of memory - prevents accidental overwrites of critical firmware or calibration sectors. |
| Low-Power Standby | 1 μA typical ICCS at 5.5 V and 125°C - enables always-on storage in battery-backed systems with multi-year shelf life. |
| Hardware Write Enable | WREN/WRDI instructions plus power-on reset of write latch - eliminates spurious writes during power ramp or brownout conditions. |
| AEC-Q100 Qualified | Grade 1 (–40°C to +125°C) qualification - validates reliability for automotive body control modules, ADAS sensors, and infotainment subsystems. |
| HOLD Functionality | Bus-suspend capability with no sequence restart - allows host MCU to service higher-priority interrupts without corrupting ongoing EEPROM reads/writes. |
Applications
| Automotive Telematics Unit | Industrial PLC Configuration Storage |
|---|---|
|
Use Scenario: Storing GPS module calibration offsets, SIM card credentials, and OTA update metadata in a vehicle-mounted telematics gateway. IC Role / Device Role / Timing Role: Nonvolatile configuration register holding persistent settings that survive ignition cycling and ECU resets. Use Value: Enables secure, field-upgradable device identity and location services without requiring external backup power or FRAM cost premium. |
Use Scenario: Retaining I/O mapping tables, PID tuning parameters, and safety interlock states in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: Dedicated parameter EEPROM interfaced directly to PLC's ARM Cortex-M7 SPI peripheral. Use Value: Guarantees >200-year data retention and 1M endurance for infrequent but mission-critical configuration updates across 15+ year equipment lifecycles. |
| Medical Infusion Pump Calibration | Smart Energy Meter Firmware Flags |
|
Use Scenario: Archiving per-pump flow rate calibration coefficients, operator audit logs, and regulatory compliance timestamps in Class II medical devices. IC Role / Device Role / Timing Role: Safety-critical data logger with hardware write protection (WP pin + BP bits) preventing unauthorized parameter modification. Use Value: Meets IEC 62304 software lifecycle requirements through deterministic 5 ms write cycles and AEC-Q100-grade reliability validation. |
Use Scenario: Storing tariff schedules, meter firmware version hashes, and tamper-detection event counters in ANSI C12.20-compliant smart electricity meters. IC Role / Device Role / Timing Role: Secure boot parameter store accessed during cold start to validate firmware integrity before execution. Use Value: Leverages 1.8 V operation to interface directly with ultra-low-power metrology SoCs, reducing BOM count versus discrete level-shifting solutions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC256-I/SN | Requires 2.5–5.5 V VCC; lacks 1.8 V operation; otherwise identical pinout, timing, and feature set. | Not suitable for 1.8 V or 2.5 V-only systems; acceptable where board already uses 3.3 V or 5 V supply rails. | Select 25LC256-I/SN only if system VCC ≥ 2.5 V and extended low-voltage operation is unnecessary. |
| AT25DF256A-SSH-T | Quad SPI interface, 32 Mbit density, 2.7–3.6 V only; no HOLD or WP pins; different command set and status register layout. | Designed for high-speed firmware code shadowing, not parameter storage; incompatible with standard SPI EEPROM drivers. | Choose AT25DF256A-SSH-T only for boot code acceleration in 3.3 V systems; not a functional substitute for 25AA256-E/SN in configuration storage roles. |
Compared with 25LC256-I/SN and AT25DF256A-SSH-T, the 25AA256-E/SN uniquely supports 1.8 V operation and automotive-grade temperature range while maintaining full SPI EEPROM software compatibility - making it the only drop-in option for low-voltage, high-reliability parameter storage.
Availability
25AA256-E/SN is available at Aetrix Electronics and suitable for automotive telematics, industrial PLCs, medical infusion pumps, and smart energy meter designs requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for 25AA256-E/SN 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 25AA256-E/SN belongs to Microchip's serial EEPROM product line, engineered specifically for robust, low-power, and automotive-qualified nonvolatile data storage in space- and cost-constrained embedded systems.
FAQ
What is the minimum supply voltage required for reliable operation of the 25AA256-E/SN?
The 25AA256-E/SN supports operation down to 1.8 V across its full –40°C to +125°C temperature range. Below 1.8 V, read/write functionality is not guaranteed per datasheet specifications. This makes the 25AA256-E/SN suitable for battery-powered or energy-harvesting systems where supply voltage may dip near 1.8 V during brownout conditions. Always verify VCC stability with appropriate decoupling capacitors.
Does the 25AA256-E/SN support SPI Mode 1,1 or only Mode 0,0?
The 25AA256-E/SN is specified exclusively for SPI Mode 0,0 (CPOL = 0, CPHA = 0), meaning data is sampled on the rising edge of SCK and output on the falling edge. Attempting to use Mode 1,1 will result in incorrect data capture or communication failure. The 25AA256-E/SN does not auto-detect or adapt to alternate SPI modes - firmware must configure the host controller accordingly.
How does the HOLD pin function during an active read sequence on the 25AA256-E/SN?
When HOLD is pulled low during an active read sequence on the 25AA256-E/SN, the device immediately tri-states SO and ignores further SCK transitions, preserving the internal address pointer and byte counter. Upon returning HOLD to high (while SCK is low), the read resumes from the exact byte position where it was paused - enabling deterministic interrupt servicing without data loss or reinitialization overhead.
Can the 25AA256-E/SN be used as a direct replacement for the 25LC256-I/SN in an existing design?
The 25AA256-E/SN is pin- and software-compatible with the 25LC256-I/SN, sharing identical SOIC-8 (SN) packaging, SPI command set, and register map. However, because the 25AA256-E/SN operates down to 1.8 V while the 25LC256-I/SN requires ≥2.5 V, substitution is safe only if the host system's VCC remains within 1.8–5.5 V. No PCB or firmware changes are needed beyond verifying supply voltage compliance.
What happens if a page write crosses a 64-byte boundary on the 25AA256-E/SN?
If a page write command on the 25AA256-E/SN attempts to write across a 64-byte physical boundary (e.g., writing 10 bytes starting at address 0x003E), the excess bytes wrap around to the start of the same page (0x0000–0x003F), overwriting previously written data. The 25AA256-E/SN does not auto-align or reject such commands - this behavior must be prevented in firmware by validating address alignment prior to initiating page writes.
25AA256-E/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
25AA256-E/SN FAQ
1.How can I place an order for 25AA256-E/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA256-E/SN 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 25AA256-E/SN reliable?
The price and inventory of 25AA256-E/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA256-E/SN is usually 5 days.
3.What payment methods are accepted for 25AA256-E/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA256-E/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA256-E/SN?
25AA256-E/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA256-E/SN 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 25AA256-E/SN?
For technical support, including 25AA256-E/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA256-E/SN requirements.
6.How does Aetrix verify that 25AA256-E/SN is sourced from the original manufacturer or authorized distributors?
All 25AA256-E/SN 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 25AA256-E/SN meets industry standards.
7.What is the process for return or replacement of 25AA256-E/SN?
All 25AA256-E/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25AA256-E/SN, 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 25AA256-E/SN part is unused and in its original packaging.
Return procedure for 25AA256-E/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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