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Microchip Technology 24CS256T-E/OT

Name: 24CS256T-E/OT
Brand: Microchip Technology
SKU: 24CS256T-E/OT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 24CS256T-E/OT

Manufacturer:: Microchip Technology

Category:: Memory

Package:: SC-74A, SOT-753

Datasheet:: 24CS256T-E/OT.pdf

Description:: IC EEPROM 256KBIT I2C SOT23-5

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Inventory:3,000

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Product details

Overview

24CS256T-E/OT from Microchip Technology is a 256-Kbit I²C serial EEPROM organized as 32,768 × 8-bit, supporting byte/page writes (up to 64 bytes), self-timed write cycles ≤5 ms, and high-speed I²C up to 3.4 MHz. It features a factory-programmed 128-bit serial number, user-lockable 64-byte ID page, built-in ECC for single-bit error correction, and hardware/software write protection - deployed in automotive infotainment control modules for firmware parameter storage.

For engineers reviewing the 24CS256T-E/OT datasheet, 24CS256T-E/OT pinout, 24CS256T-E/OT application, or 24CS256T-E/OT equivalent, key selection criteria include extended temperature support (–40°C to +125°C), AEC-Q100 qualification, 1.7V–5.5V operating voltage, integrated security register, and dual-mode write protection (WP pin + configurable zone locking).

Technical Context

The 24CS256T-E/OT implements a two-wire I²C interface with Schmitt-trigger inputs, slope-controlled outputs, and programmable High-Speed mode (3.4 MHz at VCC ≥2.5V). Its memory architecture comprises a 256-Kbit main array (0000h–7FFFh) and a separate 1-Kbit Security register (0800h–087Fh), split into read-only 128-bit serial number (0800h–080Fh) and lockable user ID page (0840h–087Fh).

Device operation is governed by three dedicated registers: Configuration register (enables enhanced software write protection per 32-Kbit zone), Security register (supports irreversible ID page locking), and Manufacturer ID register (24-bit I²C-compliant identifier). Write protection can be configured via WP pin (hardware) or Configuration register bits (software), with the latter allowing independent locking of eight 32-Kbit zones.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	256 Kbit (32,768 × 8-bit), organized in 512 pages of 64 bytes each - enables efficient bulk configuration storage with page-write efficiency.
I²C Speed Support	Up to 3.4 MHz (High-Speed mode), plus 1 MHz / 400 kHz / 100 kHz - ensures compatibility with legacy and high-throughput microcontrollers.
Write Cycle Time	≤5 ms max (self-timed), supports byte or 64-byte page writes - reduces host MCU wait time and improves system responsiveness.
Operating Voltage	1.7V to 5.5V - allows direct interfacing with 1.8V, 3.3V, and 5V logic systems without level-shifting.
Temperature Range	–40°C to +125°C (Extended grade, E-temp) - qualified for under-hood automotive and industrial edge environments.
Data Retention	>200 years at 55°C - guarantees long-term reliability for calibration data and firmware metadata in unattended deployments.
Endurance	1,000,000 erase/write cycles - supports frequent field-updatable parameters in telematics and ADAS subsystems.

Pinout & Package

24CS256T-E/OT is packaged in an 8-lead UDFN (2 mm × 3 mm, wettable flank) with exposed pad - optimized for automated optical inspection (AOI) and thermal performance in space-constrained automotive PCBs.

Pin/Terminal	Circuit Role	Design Meaning
A0	Hardware Address Input	LSB of 3-bit device address; sets I²C client address (000–111) to allow up to eight devices on one bus.
A1	Hardware Address Input	Middle bit of 3-bit device address; must be hardwired to VSS or VCC - no floating connections permitted.
A2	Hardware Address Input	MSB of 3-bit device address; determines unique I²C address when multiple 24CS256T-E/OT devices share SDA/SCL lines.
VSS	Ground Reference	Primary return path for all internal circuitry; exposed pad (Pin 5) may be connected to VSS for improved thermal dissipation.
SDA	Serial Data Line	Open-drain bidirectional I²C data line requiring external pull-up; supports ACK/NACK signaling and multi-master arbitration.
SCL	Serial Clock Line	Input-only clock line synchronized to host MCU; rise/fall times controlled to meet HS-mode timing (≤60 ns high time, ≤160 ns low time).
WP	Write-Protect Control	Active-high hardware lock: tied to VCC disables all writes to main array and Security register; ignored in Enhanced Software Protection mode.
VCC	Power Supply	Single supply input (1.7–5.5V); internal POR circuit enforces 100 µs delay after stable VCC before accepting commands.

Key Features

Feature	Design Value
Factory-Programmed 128-Bit Serial Number	Globally unique identifier preloaded in Security register (0800h–080Fh) - eliminates manufacturing serialization overhead and enables secure device identity binding.
User-Programmable & Lockable ID Page	64-byte EEPROM section (0840h–087Fh) that can be permanently locked via software sequence - protects critical calibration or cryptographic keys from overwrite.
Built-In Error Correction Code (ECC)	Corrects up to one bit error per 4-byte read; Error Correction State (ECS) latch in Configuration register flags correction events - enhances data integrity in electrically noisy automotive environments.
Dual Write Protection Modes	Hardware (WP pin) + software (Configuration register) - enables flexible security policies: full-array lock during production, or per-zone protection for field updates.
I²C Manufacturer Identification Function	Returns unique 24-bit ID on command - allows runtime verification of device authenticity and prevents counterfeit substitution in supply chain-critical applications.

Applications

Automotive Body Control Module (BCM)	Industrial PLC Configuration Storage
Use Scenario: Storing vehicle-specific door lock logic, mirror position presets, and lighting profiles across ignition cycles. IC Role / Device Role / Timing Role: Nonvolatile parameter store accessed via I²C during boot and runtime; ECC ensures integrity of safety-critical settings. Use Value: Eliminates need for external serialization and enables over-the-air (OTA) parameter updates with tamper-resistant ID page locking.	Use Scenario: Retaining I/O mapping, PID tuning constants, and alarm thresholds in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: Persistent configuration memory with AEC-Q100-grade reliability; operates continuously at 85°C ambient in control cabinets. Use Value: >200-year data retention and 1M endurance support decades-long deployment without maintenance or recalibration.
Medical Infusion Pump Calibration	Smart Energy Meter Firmware Metadata
Use Scenario: Securing pump delivery rate calibration coefficients and operator audit logs in Class II medical devices. IC Role / Device Role / Timing Role: Security register stores cryptographically signed calibration data; 128-bit serial number binds firmware to hardware. Use Value: Factory-programmed serial number + lockable ID page satisfy IEC 62304 traceability and FDA design control requirements.	Use Scenario: Storing firmware version stamps, meter serial numbers, and tariff schedule timestamps in ANSI C12.22-compliant smart meters. IC Role / Device Role / Timing Role: High-reliability EEPROM with ECC and 125°C rating withstands transformer-coupled surge environments and outdoor enclosures. Use Value: Dual write protection modes prevent accidental corruption during firmware upgrades while enabling secure field provisioning.

Automotive Body Control Module (BCM)

Industrial PLC Configuration Storage

Use Scenario: Storing vehicle-specific door lock logic, mirror position presets, and lighting profiles across ignition cycles.

IC Role / Device Role / Timing Role: Nonvolatile parameter store accessed via I²C during boot and runtime; ECC ensures integrity of safety-critical settings.

Use Value: Eliminates need for external serialization and enables over-the-air (OTA) parameter updates with tamper-resistant ID page locking.

Use Scenario: Retaining I/O mapping, PID tuning constants, and alarm thresholds in programmable logic controllers deployed in factory automation.

IC Role / Device Role / Timing Role: Persistent configuration memory with AEC-Q100-grade reliability; operates continuously at 85°C ambient in control cabinets.

Use Value: >200-year data retention and 1M endurance support decades-long deployment without maintenance or recalibration.

Medical Infusion Pump Calibration

Smart Energy Meter Firmware Metadata

Use Scenario: Securing pump delivery rate calibration coefficients and operator audit logs in Class II medical devices.

IC Role / Device Role / Timing Role: Security register stores cryptographically signed calibration data; 128-bit serial number binds firmware to hardware.

Use Value: Factory-programmed serial number + lockable ID page satisfy IEC 62304 traceability and FDA design control requirements.

Use Scenario: Storing firmware version stamps, meter serial numbers, and tariff schedule timestamps in ANSI C12.22-compliant smart meters.

IC Role / Device Role / Timing Role: High-reliability EEPROM with ECC and 125°C rating withstands transformer-coupled surge environments and outdoor enclosures.

Use Value: Dual write protection modes prevent accidental corruption during firmware upgrades while enabling secure field provisioning.

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 128-bit serial number; no ECC; max I²C speed 1 MHz; only 1.7–5.5V, –40°C to +85°C.	Lacks automotive-grade reliability features and cryptographic identity support - suitable for cost-sensitive consumer electronics.	Select only if security, ECC, and extended temperature are not required; not AEC-Q100 qualified.
24AA256-I/SM	Same pinout but no Security register, no ECC, no High-Speed mode (max 400 kHz); rated –40°C to +85°C only; no AEC-Q100 qualification.	Lower-cost alternative for industrial control where extended temp and automotive qualification are unnecessary.	Use where basic 256-Kbit I²C EEPROM suffices; avoid in safety-critical or high-temperature deployments.

Compared with AT24C256C-SSHL-T and 24AA256-I/SM, the 24CS256T-E/OT delivers differentiated value through factory-serialized identity, on-the-fly ECC correction, AEC-Q100 compliance, and dual-mode write protection - making it the sole choice for automotive, medical, and infrastructure applications demanding traceability and long-term data integrity.

Availability

24CS256T-E/OT is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for 24CS256T-E/OT 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 global semiconductor company specializing in microcontrollers, analog, FPGA, and memory solutions, with emphasis on reliability, security, and long-term product availability.

The 24CS256T-E/OT belongs to Microchip's CS-series serial EEPROM family, designed specifically for automotive and industrial applications requiring certified reliability, cryptographic identity, and robust nonvolatile storage under harsh environmental conditions.

FAQ

What is the maximum I²C clock frequency supported by the 24CS256T-E/OT?

The 24CS256T-E/OT supports High-Speed I²C mode up to 3.4 MHz when VCC is ≥2.5V and operating in Industrial temperature range. At lower voltages (1.7–2.5V) or Extended temperature (–40°C to +125°C), maximum clock frequency is 1 MHz. All standard modes (100 kHz, 400 kHz) are fully backward compatible. This enables flexible integration with both legacy and next-generation microcontrollers without protocol changes.

Does the 24CS256T-E/OT include built-in error correction?

Yes, the 24CS256T-E/OT integrates hardware-based Error Correction Code (ECC) logic that automatically corrects up to one bit error per four-byte read. An Error Correction State (ECS) latch in the Configuration register indicates when correction has occurred. This feature significantly improves data integrity in electrically noisy environments such as automotive powertrain or industrial motor drives - a capability absent in standard 24Cxx EEPROMs like the 24AA256 or AT24C256.

How is the 128-bit serial number used in the 24CS256T-E/OT?

The 24CS256T-E/OT contains a factory-programmed, globally unique 128-bit serial number stored in the read-only portion of its Security register (addresses 0800h–080Fh). This number is guaranteed unique across the entire CS-series EEPROM family and is used to eliminate manual serialization during manufacturing. It enables secure device binding, firmware licensing, and anti-counterfeiting - accessible via standard I²C reads without special commands or unlocking sequences.

Can the 24CS256T-E/OT be used in automotive applications?

Yes, the 24CS256T-E/OT is AEC-Q100 qualified for Grade 1 (–40°C to +125°C) and rated for extended temperature operation. It meets automotive reliability requirements including >200-year data retention, 1 million write cycles, and >4 kV ESD protection. Its Security register, ECC, and dual write protection modes further support functional safety goals in body control, infotainment, and ADAS subsystems - distinguishing it from non-automotive EEPROMs like the 24LC256.

What write protection options does the 24CS256T-E/OT offer?

The 24CS256T-E/OT provides two independent write protection mechanisms: (1) Hardware protection via the WP pin (active-high, disables all writes when tied to VCC), and (2) Enhanced software protection via the Configuration register, which allows locking of any of eight independent 32-Kbit zones. Once configured, the Configuration register itself can be permanently locked - offering granular, field-updatable security unmatched by legacy EEPROMs such as the 24FC256.

24CS256T-E/OT Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: SC-74A, SOT-753

Packaging:: Tape & Reel (TR)

Product Status:: Active

Programmable:: Not Verified

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:: SOT-23-5

24CS256T-E/OT FAQ

1.How can I place an order for 24CS256T-E/OT through Aetrix?

Please submit a Request for Quotation (RFQ) for 24CS256T-E/OT 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/OT reliable?

The price and inventory of 24CS256T-E/OT 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/OT is usually 5 days.

3.What payment methods are accepted for 24CS256T-E/OT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 24CS256T-E/OT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 24CS256T-E/OT?

24CS256T-E/OT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 24CS256T-E/OT 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/OT?

For technical support, including 24CS256T-E/OT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 24CS256T-E/OT requirements.

6.How does Aetrix verify that 24CS256T-E/OT is sourced from the original manufacturer or authorized distributors?

All 24CS256T-E/OT 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/OT meets industry standards.

7.What is the process for return or replacement of 24CS256T-E/OT?

All 24CS256T-E/OT units undergo pre-shipment inspection (PSI). If there is an issue with 24CS256T-E/OT, 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/OT part is unused and in its original packaging.

Return procedure for 24CS256T-E/OT:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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