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Microchip Technology 25AA256T-E/SN
- Part No.:
- 25AA256T-E/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25AA256T-E/SN.pdf
- Description:
- IC EEPROM 256KBIT SPI 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,961
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Product details
Overview
25AA256T-E/SN from Microchip Technology Inc. is a 256 Kbit SPI Serial EEPROM with 32,768 × 8-bit organization, 64-byte page size, and 1.8–5.5 V supply range. It supports up to 10 MHz clock frequency, delivers 5 mA max write current at 5.5 V, and offers >200 years data retention - deployed in automotive instrument clusters for firmware parameter storage.
For engineers reviewing the 25AA256T-E/SN datasheet, 25AA256T-E/SN pinout, 25AA256T-E/SN application, or 25AA256T-E/SN equivalent, key selection criteria include its AEC-Q100 qualification, hardware write protection via WP pin + WPEN bit, HOLD functionality for interrupt-safe SPI pauses, and extended temperature support (−40°C to +125°C).
Technical Context
The 25AA256T-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 an 8-bit instruction register, page latches, and high-voltage generator for EEPROM programming.
Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms). The STATUS register provides real-time WIP and WEL status, while BP0/BP1 bits enable configurable block protection (none, 1/4, 1/2, or full array).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8-bit), sufficient for boot configuration, calibration tables, or device identity storage in resource-constrained systems. |
| Interface | SPI-compatible serial bus (Mode 0,0), enabling direct connection to MCU SPI peripherals without protocol translation logic. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5 V - enables fast read/write throughput (up to 1.25 MB/s theoretical burst read) in high-speed host environments. |
| Page Size | 64 bytes - defines maximum contiguous write length per command; crossing page boundary wraps data within same page. |
| Endurance | 1,000,000 erase/write cycles - supports frequent field-updatable parameters (e.g., energy meter kWh counters, sensor offset logs). |
| Data Retention | >200 years at +25°C - ensures long-term reliability for infrequently updated settings in industrial or automotive life-cycle applications. |
| Supply Voltage | 1.8–5.5 V - allows operation across wide-input power rails including single-cell Li-ion, 3.3 V logic, and legacy 5 V systems. |
| Temperature Range | −40°C to +125°C (Extended grade) - qualified for under-hood automotive, motor control, and industrial ambient environments. |
Pinout & Package
25AA256T-E/SN uses an 8-lead SOIC package (SN), 3.90 mm body width, with standard pinout compatible with industry-wide SPI EEPROM footprints.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable signal; must be low for all SPI transactions; rising edge initiates internal write cycle after valid write sequence. |
| 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 writes when WPEN bit = 1; no effect on array writes unless combined with BP bits. |
| VSS | Ground Reference | Primary return path for all internal circuitry and I/O; requires low-impedance PCB connection to minimize noise coupling during write cycles. |
| SI | Serial Data Input | Latches instructions, addresses, and data on rising edge of SCK; accepts MSB-first 8-bit commands (e.g., 0x03 for READ). |
| SCK | Serial Clock Input | Synchronizes all data transfers; timing constraints (e.g., TCSS, TCSH) tighten at lower VCC, requiring careful layout for 10 MHz operation. |
| HOLD | Hold Input | Pauses ongoing SPI transaction without resetting state; must be driven low while SCK is low to avoid metastability; tri-states SO immediately. |
| VCC | Supply Voltage | Power input supporting 1.8–5.5 V; internal regulation ensures stable EEPROM programming voltage independent of rail variation. |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Configurable via BP0/BP1 bits to protect none, upper 1/4 (6000h–7FFFh), upper 1/2 (4000h–7FFFh), or entire array - enables secure bootloader region locking. |
| Hardware Write Protection | WP pin + WPEN bit combination disables STATUS register writes only - preserves ability to update memory array while preventing accidental lockout. |
| HOLD Functionality | Enables host MCU to service higher-priority interrupts mid-transaction without losing SPI context - eliminates need for retransmission or software state tracking. |
| Low-Power Operation | 1 µA standby current at 5.5 V and 125°C - suitable for battery-backed systems where quiescent power budget is critical (e.g., smart sensors). |
| AEC-Q100 Qualification | Qualified for automotive Grade 1 (−40°C to +125°C) - meets stress test requirements for vibration, thermal cycling, and ESD (>4 kV HBM) in vehicle ECUs. |
| Self-Timed Write Cycle | Internal 5 ms max write completion time - removes need for external timeout management; WIP bit in STATUS register enables precise polling-based synchronization. |
Applications
| Automotive Instrument Cluster | Industrial PLC Configuration Storage |
|---|---|
Use Scenario: Storing odometer values, trip counters, and warning thresholds that persist across ignition cycles and battery disconnects. IC Role / Device Role / Timing Role: Nonvolatile parameter store interfaced directly to cluster MCU's SPI port; accessed during boot and periodically during runtime. Use Value: AEC-Q100 qualification and >200-year data retention ensure legal compliance and field reliability over 15+ year vehicle lifetimes. |
Use Scenario: Holding user-defined I/O mapping, PID tuning constants, and calibration offsets in modular automation controllers. IC Role / Device Role / Timing Role: SPI-configurable memory mapped into MCU's peripheral address space; written during commissioning and read at startup. Use Value: 1M endurance supports daily recalibration routines; 64-byte page writes optimize firmware update efficiency without excessive wear leveling overhead. |
| Medical Infusion Pump Settings | Smart Energy Meter Firmware Parameters |
Use Scenario: Securing drug library limits, dose safety checks, and operator audit trails in Class II medical devices requiring traceable configuration history. IC Role / Device Role / Timing Role: Protected EEPROM accessed via isolated SPI bus; WP pin tied low during production to prevent runtime corruption of safety-critical registers. Use Value: Hardware write protection + BP bits enforce regulatory requirement for immutable safety parameters; ESD >4 kV ensures robustness in hospital EMI environments. |
Use Scenario: Storing tariff schedules, meter ID, phase calibration coefficients, and tamper-event logs in ANSI C12.20-compliant electricity meters. IC Role / Device Role / Timing Role: Dual-supply tolerant (1.8–5.5 V) memory co-located with metrology SoC; HOLD used during real-time energy accumulation to pause EEPROM access. Use Value: Extended temperature rating (−40°C to +125°C) accommodates outdoor pole-mount enclosures; low 1 µA standby extends battery backup life during grid outages. |
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 supply; lacks 1.8 V operation; otherwise identical pinout, timing, and feature set. | Not suitable for ultra-low-voltage systems (e.g., coin-cell IoT sensors); acceptable for 3.3 V/5 V industrial designs. | Select 25LC256-I/SN only if system VCC never drops below 2.5 V and AEC-Q100 is not required. |
| AT25DF256A-SSH-T | Quad SPI interface (QPI mode), 3-byte addressing, deeper power-down modes (3 µA), but no HOLD pin and different command set. | Better suited for high-throughput firmware storage; incompatible with legacy SPI-only hosts requiring HOLD or standard 25XX instruction set. | Choose AT25DF256A-SSH-T only when migrating to QPI-capable MCUs and needing faster sequential reads; not drop-in replaceable. |
Compared with 25AA256T-E/SN, the 25LC256-I/SN sacrifices 1.8 V compatibility but maintains identical packaging and AEC-Q100 exemption, while the AT25DF256A-SSH-T trades HOLD and instruction compatibility for higher bandwidth and lower deep-sleep current - making each alternative optimal only in narrowly defined voltage or interface contexts.
Availability
25AA256T-E/SN is available at Aetrix Electronics and suitable for automotive instrument clusters, industrial PLCs, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature and long product lifecycles.
Supply support for 25AA256T-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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25AA256T-E/SN belongs to Microchip's serial EEPROM product line, engineered specifically for automotive and industrial applications demanding high reliability, extended temperature operation, and robust data integrity under electrical stress.
FAQ
What is the operating voltage range for the 25AA256T-E/SN?
The 25AA256T-E/SN operates from 1.8 V to 5.5 V, enabling direct integration into both low-power portable systems and legacy 5 V industrial platforms. This wide range eliminates level-shifting requirements in mixed-voltage designs and supports brown-out resilience down to 1.8 V without data corruption.
Does the 25AA256T-E/SN support hardware write protection?
Yes, the 25AA256T-E/SN supports hardware write protection through the WP pin in conjunction with the WPEN bit in its STATUS register. When WP is low and WPEN = 1, writes to nonvolatile STATUS bits are disabled - preserving critical protection settings even during firmware updates.
How does the HOLD function work on the 25AA256T-E/SN?
The HOLD pin on the 25AA256T-E/SN suspends ongoing SPI communication without resetting internal state. When asserted low while SCK is low, it tri-states SO and ignores SI/SCK transitions, allowing the host MCU to service urgent interrupts and resume exactly where it left off - a key feature for real-time deterministic systems.
What is the maximum clock frequency supported by the 25AA256T-E/SN?
The 25AA256T-E/SN supports up to 10 MHz clock frequency at VCC ≥ 4.5 V. At lower voltages (2.5 V ≤ VCC < 4.5 V), max clock drops to 5 MHz; at 1.8 V ≤ VCC < 2.5 V, it is limited to 3 MHz - AC timing parameters scale accordingly to maintain signal integrity.
Is the 25AA256T-E/SN qualified for automotive applications?
Yes, the 25AA256T-E/SN carries AEC-Q100 qualification for Grade 1 (−40°C to +125°C), including stress testing for thermal cycling, mechanical shock, and ESD (>4 kV HBM). This makes it suitable for engine control modules, ADAS sensors, and other under-hood automotive subsystems.
25AA256T-E/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
25AA256T-E/SN FAQ
1.How can I place an order for 25AA256T-E/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA256T-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 25AA256T-E/SN reliable?
The price and inventory of 25AA256T-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 25AA256T-E/SN is usually 5 days.
3.What payment methods are accepted for 25AA256T-E/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA256T-E/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA256T-E/SN?
25AA256T-E/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA256T-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 25AA256T-E/SN?
For technical support, including 25AA256T-E/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA256T-E/SN requirements.
6.How does Aetrix verify that 25AA256T-E/SN is sourced from the original manufacturer or authorized distributors?
All 25AA256T-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 25AA256T-E/SN meets industry standards.
7.What is the process for return or replacement of 25AA256T-E/SN?
All 25AA256T-E/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25AA256T-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 25AA256T-E/SN part is unused and in its original packaging.
Return procedure for 25AA256T-E/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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