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Microchip Technology 24CS256T-E/MS66KVAO
- Part No.:
- 24CS256T-E/MS66KVAO
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
24CS256T-E/MS66KVAO.pdf
- Description:
- IC EEPROM 256KBIT I2C 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,791
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Product details
Overview
24CS256T-E/MS66KVAO from Microchip Technology is a 256-Kbit I²C serial EEPROM organized as 32,768 × 8-bit, supporting high-speed mode up to 3.4 MHz, 1.7V–5.5V operation, and AEC-Q100 automotive qualification. It integrates a 128-bit factory-programmed serial number, 64-byte user-lockable ID page, and built-in ECC for single-bit error correction - deployed in vehicle infotainment configuration storage, industrial sensor calibration data retention, and medical device parameter backup.
For engineers reviewing the 24CS256T-E/MS66KVAO datasheet, 24CS256T-E/MS66KVAO pinout, 24CS256T-E/MS66KVAO application, or 24CS256T-E/MS66KVAO equivalent, key selection criteria include its extended temperature range (–40°C to +125°C), hardware/software write protection flexibility, I²C manufacturer ID support, and wettable flank VDFN-8 package compatibility with automated optical inspection.
Technical Context
The 24CS256T-E/MS66KVAO implements a two-wire I²C interface with Schmitt-trigger inputs, slope-controlled outputs, and configurable clock frequency support (100 kHz / 400 kHz / 1 MHz / 3.4 MHz). Its memory architecture comprises a 256-Kbit main array (0000h–7FFFh) and a dedicated 1-Kbit security register split into read-only 128-bit serial number (0800h–080Fh) and programmable lockable ID page (0840h–087Fh).
Write protection is implemented via dual-path control: hardware-level full-array blocking using the WP pin, and software-configurable zone protection across eight independent 32-Kbit segments via the Configuration register - which itself can be permanently locked. Built-in ECC logic corrects single-bit errors within any four-byte read window and latches error occurrence status in the ECS bit.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8-bit), enabling storage of firmware identifiers, calibration coefficients, or device-specific settings without external memory expansion |
| I²C Speed Modes | Supports 100 kHz, 400 kHz, 1 MHz, and 3.4 MHz High-Speed mode - allows integration into bandwidth-constrained or latency-sensitive systems like real-time sensor hubs |
| Operating Voltage | 1.7V to 5.5V supply range - compatible with both low-voltage microcontrollers (e.g., 1.8V ARM Cortex-M0+) and legacy 5V industrial controllers |
| Write Endurance | 1,000,000 erase/write cycles - suitable for applications requiring frequent parameter updates, such as adaptive motor control tuning tables |
| Data Retention | Greater than 200 years at 55°C - ensures long-term reliability in sealed automotive modules where field replacement is impractical |
| Temperature Range | –40°C to +125°C (Extended grade) - validated for under-hood automotive use and industrial edge computing environments |
| ESD Protection | >4000V HBM - provides robust handling during board assembly and system integration in unshielded production lines |
Pinout & Package
24CS256T-E/MS66KVAO is packaged in an 8-lead Wettable Flank VDFN (Very Thin Dual Flat No-Lead) with exposed pad, optimized for automated optical inspection (AOI) and solder joint reliability in automotive PCB assemblies.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0 | Device Address Input | Hardware-selectable LSB of 3-bit client address; enables up to eight devices on same I²C bus when tied to VSS or VCC |
| A1 | Device Address Input | Middle bit of hardware client address; must be hardwired for deterministic multi-device addressing |
| A2 | Device Address Input | MSB of hardware client address; required to be logic '0' in SOT-23 variants but fully functional here |
| VSS | Ground Reference | Primary return path for all internal circuitry; connected to exposed pad in VDFN for thermal and EMI performance |
| SDA | Serial Data Line | Open-drain bidirectional I²C data line requiring external pull-up; supports clock stretching and ACK/NACK signaling |
| SCL | Serial Clock Input | Input-only I²C clock line synchronized to host controller; includes internal Schmitt trigger for noise immunity |
| WP | Write-Protect Control | Active-high hardware lock disabling all writes to main array and security register when pulled to VCC |
| VCC | Power Supply | Single-supply input supporting 1.7V–5.5V; powers internal charge pump for EEPROM programming |
Key Features
| Feature | Design Value |
|---|---|
| Factory-Programmed 128-Bit Serial Number | Unique identifier preloaded at wafer level - eliminates post-manufacturing serialization overhead in automotive Tier-1 production lines |
| User-Programmable & Lockable ID Page | 64-byte EEPROM section (0840h–087Fh) that can be permanently write-protected via software sequence - secures cryptographic keys or calibration signatures |
| Configurable Write Protection | Switchable between legacy WP-pin mode and enhanced software-defined zone protection across eight 32-Kbit blocks - enables granular access control per subsystem |
| Built-In Error Correction Code (ECC) | Corrects single-bit errors in any four-byte read window and reports correction events via ECS latch - improves data integrity in electrically noisy engine compartments |
| I²C Manufacturer Identification Support | Returns unique 24-bit ID on command - enables runtime validation of device authenticity in secure boot sequences |
Applications
| Automotive Infotainment System | Industrial PLC Configuration Storage |
|---|---|
Use Scenario: Storing UI language preferences, display brightness profiles, and Bluetooth pairing history across ignition cycles in head unit modules. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via I²C during boot initialization and runtime parameter updates. Use Value: Leverages AEC-Q100 qualification and 125°C operation to survive under-dash thermal environments while maintaining data integrity over 15+ year vehicle lifetimes. |
Use Scenario: Retaining ladder logic configuration, I/O mapping, and alarm thresholds after power loss in modular automation controllers. IC Role / Device Role / Timing Role: Persistent parameter store interfaced with ARM-based PLC CPU via standard I²C peripheral. Use Value: Uses software zone protection to isolate critical safety parameters from routine maintenance writes, preventing accidental corruption during field firmware updates. |
| Medical Diagnostic Sensor Calibration | Smart Energy Meter Firmware Metadata |
Use Scenario: Holding factory-calibrated gain/offset coefficients and sensor linearization tables for portable ultrasound transducers. IC Role / Device Role / Timing Role: Read-once-write-rarely calibration data repository accessed during sensor self-test at power-up. Use Value: Relies on >200-year data retention and built-in ECC to guarantee accuracy compliance over device lifetime without recalibration service intervals. |
Use Scenario: Storing firmware version hash, meter serial number, and tariff schedule timestamps in utility-grade electricity meters. IC Role / Device Role / Timing Role: Secure metadata vault supporting regulatory audit trails and anti-tampering verification. Use Value: Combines 128-bit serial number and lockable ID page to bind firmware images to specific hardware units - meeting IEC 62056-21 and ANSI C12.22 requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT24C256C-SSHL-T | No security register, no ECC, max I²C speed 1 MHz, only industrial temp (–40°C to +85°C) | Lacks factory serial number and programmable ID page - unsuitable for traceability-critical automotive or medical use | Select when cost sensitivity outweighs security and extended temperature needs; verify WP pin behavior matches legacy designs |
| 24AA256-I/P | Same pinout but PDIP-8 package; no AEC-Q100 qualification; no high-speed mode (>1 MHz); no security register | Not qualified for automotive use; lacks 125°C operation and ECC - limited to benign commercial environments | Choose only for prototyping or non-automotive industrial applications where VDFN reflow compatibility is not required |
Compared with AT24C256C-SSHL-T and 24AA256-I/P, the 24CS256T-E/MS66KVAO delivers differentiated value through AEC-Q100 qualification, integrated security features, ECC-enhanced reliability, and wettable flank packaging - making it the sole option among these three qualified for production automotive ECUs requiring traceability and long-term data integrity.
Availability
24CS256T-E/MS66KVAO is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, and medical diagnostic equipment requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for 24CS256T-E/MS66KVAO 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, serving automotive, industrial, communications, and consumer markets with vertically integrated silicon and development tools.
The 24CS256 series was designed specifically for automotive and high-reliability industrial applications demanding secure, long-life nonvolatile memory - integrating unique serialization, ECC, and flexible write protection to replace discrete security + EEPROM combinations.
FAQ
What is the package type and lead finish of the 24CS256T-E/MS66KVAO?
The 24CS256T-E/MS66KVAO uses an 8-lead Wettable Flank VDFN package with matte tin lead finish. This package supports automated optical inspection (AOI) of solder joints and meets IPC/JEDEC J-STD-020 moisture sensitivity level 3 requirements. The wettable flank geometry ensures reliable solder fillet formation during reflow, critical for automotive-grade manufacturing yield.
Does the 24CS256T-E/MS66KVAO support I²C high-speed mode, and what conditions apply?
Yes, the 24CS256T-E/MS66KVAO supports I²C high-speed mode up to 3.4 MHz when operating at VCC ≥ 2.5V and within the industrial temperature range (–40°C to +85°C). High-speed mode requires external pull-up resistors sized for 330Ω and proper bus capacitance control (<400 pF). The device automatically detects and responds to high-speed start conditions without configuration.
How is the 128-bit serial number in the 24CS256T-E/MS66KVAO accessed and used?
The 128-bit serial number resides in the Security register at addresses 0800h–080Fh and is read-only. It is accessed by sending the Security register device address (1011b + A2A1A0 + R/W=1) followed by word address bytes 00h and 00h. This globally unique identifier eliminates post-production serialization steps and enables secure device binding in automotive telematics and medical device registration systems.
Can the Configuration register of the 24CS256T-E/MS66KVAO be locked permanently, and how is this done?
Yes, the Configuration register of the 24CS256T-E/MS66KVAO can be permanently locked via a software sequence defined in Section 9.0 of the datasheet. Once locked, the register becomes read-only and cannot be modified - ensuring consistent write protection behavior across the device's lifetime. This lock is irreversible and applies independently of WP pin state or power cycling.
What write protection options does the 24CS256T-E/MS66KVAO offer beyond the WP pin?
Beyond the hardware WP pin, the 24CS256T-E/MS66KVAO offers enhanced software write protection via its Configuration register. This enables selective locking of any of eight independent 32-Kbit zones - allowing fine-grained control such as protecting calibration data while permitting logging of operational parameters. Zone protection remains active even when WP is grounded.
24CS256T-E/MS66KVAO Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- maXTouch®
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- -
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- I2C
- Clock Frequency:
- 1 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- 400 ns
- Voltage - Supply:
- 1.7V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP
24CS256T-E/MS66KVAO FAQ
1.How can I place an order for 24CS256T-E/MS66KVAO through Aetrix?
Please submit a Request for Quotation (RFQ) for 24CS256T-E/MS66KVAO 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 24CS256T-E/MS66KVAO reliable?
The price and inventory of 24CS256T-E/MS66KVAO are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 24CS256T-E/MS66KVAO is usually 5 days.
3.What payment methods are accepted for 24CS256T-E/MS66KVAO?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 24CS256T-E/MS66KVAO transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 24CS256T-E/MS66KVAO?
24CS256T-E/MS66KVAO orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 24CS256T-E/MS66KVAO 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 24CS256T-E/MS66KVAO?
For technical support, including 24CS256T-E/MS66KVAO datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 24CS256T-E/MS66KVAO requirements.
6.How does Aetrix verify that 24CS256T-E/MS66KVAO is sourced from the original manufacturer or authorized distributors?
All 24CS256T-E/MS66KVAO 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 24CS256T-E/MS66KVAO meets industry standards.
7.What is the process for return or replacement of 24CS256T-E/MS66KVAO?
All 24CS256T-E/MS66KVAO units undergo pre-shipment inspection (PSI). If there is an issue with 24CS256T-E/MS66KVAO, 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 24CS256T-E/MS66KVAO part is unused and in its original packaging.
Return procedure for 24CS256T-E/MS66KVAO:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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