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Home > Products > Integrated Circuits (ICs) > Memory > Memory

Microchip Technology 24CS256T-E/ST

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

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Part No.:: 24CS256T-E/ST

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 8-TSSOP (0.173", 4.40mm Width)

Datasheet:: 24CS256T-E/ST.pdf

Description:: IC EEPROM 256KBIT I2C 8TSSOP

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Inventory:2,488

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Product details

Overview

24CS256T-E/ST 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 control modules for firmware versioning and calibration data storage.

For engineers reviewing the 24CS256T-E/ST datasheet, 24CS256T-E/ST pinout, 24CS256T-E/ST application, or 24CS256T-E/ST equivalent, key selection criteria include I²C high-speed timing compliance (THIGH ≤ 60 ns at 3.4 MHz), WP pin hardware write protection, dual-zone software-configurable memory protection, ECC latch reporting via Configuration register, and extended temperature support (-40°C to +125°C) for under-hood automotive use.

Technical Context

The 24CS256T-E/ST implements a two-wire I²C interface with Schmitt-trigger inputs and slope-controlled outputs to suppress ground bounce and noise. Its internal architecture separates the 256-Kbit main array from a dedicated 1-Kbit Security register containing read-only serial number (0800h–080Fh) and programmable lockable ID page (0840h–087Fh).

Write operations are self-timed (≤5 ms), supported in byte or 64-byte page mode, and governed by a configurable Configuration register that enables either legacy WP-pin-based full-array protection or enhanced software-defined zone protection across eight independent 32-Kbit blocks. The device reports ECC invocation status via a read-only Error Correction State (ECS) latch.

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 parameter storage with page-aligned writes.
I²C Speed Support	Up to 3.4 MHz (High-Speed mode), plus 1 MHz / 400 kHz / 100 kHz - ensures compatibility with modern microcontrollers and real-time logging systems.
Operating Voltage	1.7V to 5.5V - supports direct interfacing with 1.8V, 3.3V, and 5V logic domains without level shifters.
Temperature Range	-40°C to +125°C (Extended grade) - qualified for engine control units, ADAS sensors, and other under-hood automotive applications.
Write Endurance	1,000,000 erase/write cycles - sufficient for frequent calibration updates over 15+ years of vehicle service life.
Data Retention	>200 years at 55°C - guarantees long-term integrity of VIN, security keys, and regulatory configuration data.
ECC Capability	Corrects up to one bit error per 4-byte read - mitigates soft errors in safety-critical automotive firmware storage without host-side intervention.

Pinout & Package

24CS256T-E/ST is packaged in an 8-lead SOIC (Small Outline Integrated Circuit) with gull-wing leads, RoHS-compliant matte tin finish, and wettable flank geometry for automated optical inspection (AOI) and solder joint reliability validation.

Pin/Terminal	Circuit Role	Design Meaning
A0	Hardware Address Input	LSB of 3-bit device address; hardwired to VSS or VCC to select one of eight possible I²C addresses on shared bus.
A1	Hardware Address Input	Middle bit of 3-bit device address; enables multi-device topology without address conflict in telematics gateways.
A2	Hardware Address Input	MSB of 3-bit device address; allows stacking of up to eight 24CS256T-E/ST devices on same I²C bus for modular ECU designs.
VSS	Ground Reference	Primary return path for all internal circuitry and I/O; must be low-impedance connection to minimize noise coupling into SDA/SCL lines.
SDA	Serial Data Line	Open-drain bidirectional I²C data line requiring external pull-up; supports clock stretching and ACK/NACK signaling per I²C specification.
SCL	Serial Clock Line	Input-only I²C clock line; slope control ensures clean edges even with high bus capacitance in distributed automotive networks.
WP	Write-Protect Control	Active-high hardware lock: tied to VCC disables all writes to main array and Security register, enabling field-safe read-only operation.
VCC	Power Supply	Single-supply input (1.7V–5.5V); internal POR circuit enforces 100 µs delay after stable VCC before accepting commands.

Key Features

Feature	Design Value
Factory-Preprogrammed Serial Number	Globally unique 128-bit identifier stored in read-only Security register (0800h–080Fh), eliminating manufacturing serialization overhead in Tier-1 production lines.
User-Programmable Lockable ID Page	64-byte EEPROM section (0840h–087Fh) that can be permanently write-locked via software sequence - ideal for storing cryptographic keys or calibration certificates.
Enhanced Software Write Protection	Configuration register enables per-zone (32-Kbit) protection independent of WP pin state - supports secure boot partitioning and OTA update rollback safeguards.
I²C Manufacturer ID Function	Returns unique 24-bit vendor ID upon host query - enables automatic device identification and firmware compatibility verification during system initialization.
ESD Robustness	>4000V HBM rating - meets stringent automotive EMC requirements for module-level integration without additional transient suppression.

Applications

Automotive Instrument Cluster	Industrial PLC Configuration Storage
Use Scenario: Storing odometer readings, warning light configurations, and driver preference profiles across ignition cycles. IC Role / Device Role / Timing Role: Nonvolatile parameter retention IC with AEC-Q100 qualification and ECC-protected reads ensuring data integrity during voltage transients. Use Value: Prevents loss of critical vehicle metrics during battery disconnect events and extends flash endurance by offloading frequent writes from MCU internal flash.	Use Scenario: Holding I/O mapping tables, PID tuning parameters, and firmware revision history in programmable logic controllers operating in factory environments. IC Role / Device Role / Timing Role: High-reliability serial EEPROM interfaced via industrial-grade I²C bus with 3.4 MHz throughput for rapid configuration reload after power loss. Use Value: Enables zero-downtime reconfiguration via hot-swap capable memory with hardware WP pin preventing accidental overwrites during maintenance.
Medical Infusion Pump Calibration	Smart Energy Meter Firmware Vault
Use Scenario: Securing pump delivery rate calibration constants, sensor offset values, and audit logs subject to FDA 21 CFR Part 11 compliance. IC Role / Device Role / Timing Role: Tamper-evident storage element with lockable 64-byte ID page for cryptographic signature binding and ECC-verified readback. Use Value: Provides immutable traceability of calibration events and satisfies regulatory requirements for data authenticity and retention beyond device lifetime.	Use Scenario: Storing meter firmware signatures, tariff schedules, and tamper-detection event logs in utility-grade smart meters deployed in harsh outdoor environments. IC Role / Device Role / Timing Role: Extended-temperature EEPROM with >200-year data retention and 1M-cycle endurance for decade-long field deployments without maintenance. Use Value: Eliminates need for battery-backed SRAM while guaranteeing legal metrology data integrity under thermal cycling and voltage brownout conditions.

Automotive Instrument Cluster

Industrial PLC Configuration Storage

Use Scenario: Storing odometer readings, warning light configurations, and driver preference profiles across ignition cycles.

IC Role / Device Role / Timing Role: Nonvolatile parameter retention IC with AEC-Q100 qualification and ECC-protected reads ensuring data integrity during voltage transients.

Use Value: Prevents loss of critical vehicle metrics during battery disconnect events and extends flash endurance by offloading frequent writes from MCU internal flash.

Use Scenario: Holding I/O mapping tables, PID tuning parameters, and firmware revision history in programmable logic controllers operating in factory environments.

IC Role / Device Role / Timing Role: High-reliability serial EEPROM interfaced via industrial-grade I²C bus with 3.4 MHz throughput for rapid configuration reload after power loss.

Use Value: Enables zero-downtime reconfiguration via hot-swap capable memory with hardware WP pin preventing accidental overwrites during maintenance.

Medical Infusion Pump Calibration

Smart Energy Meter Firmware Vault

Use Scenario: Securing pump delivery rate calibration constants, sensor offset values, and audit logs subject to FDA 21 CFR Part 11 compliance.

IC Role / Device Role / Timing Role: Tamper-evident storage element with lockable 64-byte ID page for cryptographic signature binding and ECC-verified readback.

Use Value: Provides immutable traceability of calibration events and satisfies regulatory requirements for data authenticity and retention beyond device lifetime.

Use Scenario: Storing meter firmware signatures, tariff schedules, and tamper-detection event logs in utility-grade smart meters deployed in harsh outdoor environments.

IC Role / Device Role / Timing Role: Extended-temperature EEPROM with >200-year data retention and 1M-cycle endurance for decade-long field deployments without maintenance.

Use Value: Eliminates need for battery-backed SRAM while guaranteeing legal metrology data integrity under thermal cycling and voltage brownout conditions.

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 built-in ECC; no Security register; max I²C speed 1 MHz; no AEC-Q100 qualification.	Lacks serial number, lockable ID, and ECC - unsuitable for automotive safety-critical or regulatory-auditable use cases.	Select only for cost-sensitive consumer electronics where ECC and serialization are nonessential.
24AA256-I/SM	Same pinout but Industrial temp only (-40°C to +85°C); no extended temp grade; no 3.4 MHz support; no manufacturer ID function.	Cannot replace 24CS256T-E/ST in under-hood or high-ambient-temperature deployments requiring +125°C operation.	Acceptable for cabin-mounted automotive modules or industrial controls within standard temperature envelope.

Compared with AT24C256C-SSHL-T and 24AA256-I/SM, the 24CS256T-E/ST delivers differentiated value through AEC-Q100 qualification, ECC-enabled reliability, factory-serialized identity, and extended temperature support - making it the sole choice for automotive Tier-1 and medical OEM designs requiring certified data integrity.

Availability

24CS256T-E/ST is available at Aetrix Electronics and suitable for automotive ECU development, industrial PLC configuration storage, and medical device calibration data retention requiring stable component supply across multi-year production lifecycles.

Supply support for 24CS256T-E/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 microcontroller, analog, FPGA, and memory solutions, serving automotive, industrial, communications, and consumer markets with vertically integrated silicon and software platforms.

The 24CS256 product line was designed specifically for automotive and high-reliability industrial applications requiring certified nonvolatile memory with embedded security features, extended temperature operation, and robust I²C communication.

FAQ

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

The 24CS256T-E/ST supports High-Speed mode up to 3.4 MHz when VCC ≥ 2.5V and operating in Industrial temperature range. At lower voltages (1.7V–2.5V) or Extended temperature range, maximum clock frequency is limited to 1 MHz. Timing parameters including THIGH (60 ns min) and TLOW (160 ns min) are specified in DS20005998D, Table 1-2. The 24CS256T-E/ST must be configured for HS mode via the Configuration register to enable 3.4 MHz operation.

Does the 24CS256T-E/ST include error correction capability, and how is it implemented?

Yes, the 24CS256T-E/ST incorporates built-in Error Correction Code (ECC) logic that corrects up to one bit error per four-byte readout. The ECC state is reported via a read-only Error Correction State (ECS) latch in the Configuration register. When ECC correction is invoked during a read, the ECS latch is set and remains asserted until cleared by a subsequent read operation. This feature is active across the entire 256-Kbit memory array and does not require host-side firmware intervention.

How is the 128-bit serial number accessed and used in the 24CS256T-E/ST?

The 128-bit serial number in the 24CS256T-E/ST is factory-programmed, globally unique, and stored in the read-only portion of the Security register at addresses 0800h–080Fh. It is accessed using the Security register device address (1011b + A2A1A0 + R/W) and first word address byte format (0xxx10xx). The serial number eliminates post-manufacturing serialization steps and enables secure device authentication in automotive keyless entry and telematics systems.

Can the 24CS256T-E/ST be used in place of older 24LC256 or 24AA256 devices?

The 24CS256T-E/ST is backward compatible with 24AA256/24LC256/24FC256 and AT24C256C serial EEPROMs at the electrical and protocol level, sharing identical pinout, I²C addressing, and basic command structure. However, advanced features like ECC, Security register, and Configuration register require updated firmware to access. For drop-in replacement in legacy designs without feature utilization, the 24CS256T-E/ST operates identically - but full benefit requires enabling new capabilities via documented register sequences.

What write protection mechanisms does the 24CS256T-E/ST provide, and how do they differ?

The 24CS256T-E/ST offers dual write protection: (1) Hardware protection via the WP pin - tying WP to VCC inhibits all writes to both main array and Security register; (2) Enhanced software protection via the Configuration register - allowing independent locking of any of eight 32-Kbit zones, regardless of WP pin state. Once the Configuration register is locked, protection settings become permanent. This layered approach supports both field-safe read-only operation and fine-grained firmware partitioning in safety-critical systems.

24CS256T-E/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:: -

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-TSSOP

24CS256T-E/ST FAQ

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

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

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

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

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

Note: Certain payment methods may incur a processing fee.

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

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

Once your 24CS256T-E/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 24CS256T-E/ST?

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

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

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

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

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

Return procedure for 24CS256T-E/ST:

1.Submit a request within 90 days.

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

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