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Microchip Technology 25AA256T-I/ST
- Part No.:
- 25AA256T-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25AA256T-I/ST.pdf
- Description:
- IC EEPROM 256KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,088
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Product details
Overview
25AA256T-I/ST 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 temperature support (−40°C to +85°C). It features hardware write protection via WP pin and STATUS register, HOLD functionality for interrupt-safe bus suspension, and AEC-Q100 qualification for automotive use.
For engineers reviewing the 25AA256T-I/ST datasheet, 25AA256T-I/ST pinout, 25AA256T-I/ST application, or 25AA256T-I/ST equivalent, key selection criteria include its 10 MHz max clock at 4.5–5.5 V, 1 μA standby current, 1M endurance cycles, >200-year data retention, and TSSOP-8 package compatibility with space-constrained embedded control and automotive subsystems.
Technical Context
The 25AA256T-I/ST implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (input) and SO (output) lines, requiring CS, SCK, SI, SO, WP, HOLD, VCC, and VSS. Its internal architecture includes a write-enable latch, nonvolatile STATUS register (BP0/BP1/WEL/WIP), and page latches enabling up to 64-byte writes within aligned 64-byte boundaries.
Write operations are self-timed (≤5 ms), with built-in power-on write protection, automatic WEL reset after write completion, and hardware-controlled block protection covering none, 1/4, 1/2, or full memory array. The HOLD pin suspends ongoing serial transfers without resetting sequence state, supporting deterministic interrupt handling in real-time systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits) - supports firmware parameter storage, calibration data, and event logs in resource-limited microcontroller systems |
| Interface | SPI-compatible serial bus (Mode 0,0 / Mode 1,1) - interoperable with PIC® and other MCU SPI peripherals without protocol translation |
| 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 control loops |
| Page Size | 64 bytes - constrains write bursts to single-page boundaries; crossing pages wraps data instead of advancing, requiring software address validation |
| Endurance | 1,000,000 erase/write cycles - suitable for logging applications with frequent updates (e.g., battery cycle counters, error history) |
| Data Retention | >200 years at 25°C - ensures long-term integrity of configuration and calibration data across product lifetime |
| Supply Voltage | 1.8–5.5 V - supports direct interfacing with 1.8 V logic, 3.3 V I/O, and 5 V legacy systems without level shifters |
Pinout & Package
25AA256T-I/ST is housed in an 8-lead Thin Shrink Small Outline Package (TSSOP-8), 4.4 mm body width, RoHS-compliant, with gull-wing leads and JEDEC-standard pinout. Pin 1 is marked by a dot or beveled corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable; deselecting places SO in high-impedance to share SPI bus with multiple devices |
| SO | Serial Data Output | Tri-state output; data valid after falling edge of SCK; high-Z when CS high or HOLD low |
| WP | Write-Protect Input | Hardware lock for STATUS register when WPEN=1; low = protect nonvolatile BP/WPEN bits; no effect on array writes unless enabled |
| VSS | Ground Reference | Primary return path for all digital and internal charge-pump circuits; must be low-impedance connection |
| SI | Serial Data Input | Latches instruction, address, and data on rising edge of SCK; accepts MSB-first SPI frames |
| SCK | Serial Clock Input | Synchronizes all data transfers; timing parameters (e.g., TCSS, THD) scale with VCC voltage tier |
| HOLD | Bus Hold Control | Active-low pause signal; must be asserted while SCK is low to avoid metastability; tri-states SO immediately |
| VCC | Power Supply | 1.8–5.5 V input powering logic, EEPROM array, and internal HV generator; bypass capacitor required |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Selectable via STATUS register (BP0/BP1): protect none, upper 1/4 (6000h–7FFFh), upper 1/2 (4000h–7FFFh), or entire array (0000h–7FFFh) |
| Hardware Write Enable Latch | WREN/WRDI instructions control volatile write permission; automatically resets after power-up, write completion, or WRSR execution |
| HOLD Functionality | Pauses active SPI transfer mid-sequence without losing state; resumes from exact bit position on HOLD high (SCK low required) |
| Low-Power Operation | 1 μA standby current at 5.5 V/125°C enables always-on storage in battery-powered nodes and energy-harvesting systems |
| AEC-Q100 Qualification | Qualified for automotive applications per Grade 2 (−40°C to +105°C ambient) - validated for engine control, ADAS sensors, and infotainment modules |
Applications
| Automotive Body Control Module | Industrial PLC Configuration Storage |
|---|---|
Use Scenario: Storing door lock settings, mirror position presets, and lighting profiles in vehicle body controllers. IC Role / Device Role / Timing Role: Nonvolatile parameter memory accessed via SPI during boot and runtime; retains values across ignition cycles. Use Value: Enables user-customizable features without external backup batteries; AEC-Q100 qualification ensures reliability under thermal cycling and vibration. |
Use Scenario: Holding I/O mapping tables, PID tuning constants, and alarm thresholds in programmable logic controllers. IC Role / Device Role / Timing Role: Configuration EEPROM interfaced to ARM Cortex-M host MCU; updated only during commissioning or maintenance mode. Use Value: 1M endurance supports field recalibration over 10+ years; 1.8–5.5 V range simplifies integration with diverse 3.3 V/5 V PLC power domains. |
| Medical Infusion Pump Calibration | Smart Meter Firmware Patch Storage |
Use Scenario: Archiving flow rate calibration coefficients, sensor offset corrections, and usage audit logs in Class II medical devices. IC Role / Device Role / Timing Role: Secure, tamper-resistant storage accessed during self-test and dose delivery sequences. Use Value: Hardware WP pin + BP bits prevent accidental overwrite of critical calibration data; >200-year retention meets FDA long-life device requirements. |
Use Scenario: Storing signed firmware patches and cryptographic keys for secure over-the-air (OTA) updates in utility meters. IC Role / Device Role / Timing Role: Trusted storage element isolated from main flash; verified before patch application via host MCU. Use Value: Page-write efficiency (64-byte bursts) reduces OTA update time; ESD rating >4 kV ensures robustness in high-noise meter environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC256T-I/ST | 2.5–5.5 V supply range; lacks 1.8 V operation; otherwise identical pinout, timing, and feature set | Not suitable for 1.8 V logic systems; requires level-shifting if interfaced with sub-2.5 V MCUs | Select when system VCC is guaranteed ≥2.5 V and cost sensitivity favors mature 25LC variant |
| AT25DF256A-SSH-T | Dual/quad SPI interface; 2.7–3.6 V only; 256 Mbit density; no HOLD or WP pins; different command set | Higher density but incompatible protocol; requires driver rewrite and layout changes; no hardware write protection | Choose only for bandwidth-critical applications needing >10× capacity and quad-SPI acceleration; not drop-in |
Compared with 25LC256T-I/ST, the 25AA256T-I/ST enables direct 1.8 V MCU integration and broader supply flexibility, while AT25DF256A-SSH-T trades pin compatibility and protection features for higher density and faster quad-SPI throughput - making it unsuitable for legacy SPI-only or safety-critical write-protected designs.
Availability
25AA256T-I/ST is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC configuration storage, and medical infusion pump calibration requiring stable component supply, long-term lifecycle support, and AEC-Q100 compliance.
Supply support for 25AA256T-I/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 microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25AA256 belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile data storage in automotive, industrial, and medical applications where write endurance and data retention are critical.
FAQ
What is the minimum supply voltage supported by the 25AA256T-I/ST?
The 25AA256T-I/ST operates down to 1.8 V, enabling direct interface with modern ultra-low-voltage microcontrollers and battery-powered systems without level-shifting circuitry. This distinguishes it from the 25LC256 variant, which requires a minimum of 2.5 V.
Does the 25AA256T-I/ST support page write operations, and what is the maximum byte count per page?
Yes, the 25AA256T-I/ST supports page write operations with a fixed 64-byte page size. Up to 64 bytes can be written in a single transaction, provided all addresses fall within the same physical page boundary (e.g., 0x0000–0x003F); crossing boundaries causes wraparound, not auto-advancing.
How does the HOLD pin function during an active SPI transfer on the 25AA256T-I/ST?
The HOLD pin on the 25AA256T-I/ST pauses ongoing SPI communication when pulled low while SCK is low. All inputs (except CS) are ignored, SO goes high-impedance, and the internal state is preserved. Resuming requires bringing HOLD high while SCK remains low - ensuring deterministic interrupt servicing without reinitialization.
What write protection mechanisms are implemented in the 25AA256T-I/ST?
The 25AA256T-I/ST implements three-tiered write protection: (1) volatile write-enable latch (set via WREN), (2) nonvolatile STATUS register bits (BP0/BP1) for block-level array protection, and (3) hardware WP pin + WPEN bit for STATUS register lockdown. All layers must be configured correctly to prevent unintended writes.
Is the 25AA256T-I/ST qualified for automotive applications, and under which standard?
Yes, the 25AA256T-I/ST is AEC-Q100 qualified (Grade 2), certified for operation from −40°C to +105°C ambient temperature. This qualification validates its reliability for use in automotive body control, infotainment, and ADAS subsystems subject to rigorous thermal, vibration, and ESD stress testing.
25AA256T-I/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:
- 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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25AA256T-I/ST FAQ
1.How can I place an order for 25AA256T-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA256T-I/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 25AA256T-I/ST reliable?
The price and inventory of 25AA256T-I/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA256T-I/ST is usually 5 days.
3.What payment methods are accepted for 25AA256T-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA256T-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA256T-I/ST?
25AA256T-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA256T-I/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 25AA256T-I/ST?
For technical support, including 25AA256T-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA256T-I/ST requirements.
6.How does Aetrix verify that 25AA256T-I/ST is sourced from the original manufacturer or authorized distributors?
All 25AA256T-I/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 25AA256T-I/ST meets industry standards.
7.What is the process for return or replacement of 25AA256T-I/ST?
All 25AA256T-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25AA256T-I/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 25AA256T-I/ST part is unused and in its original packaging.
Return procedure for 25AA256T-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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