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

Microchip Technology 24CS256-E/SM

Name: 24CS256-E/SM
Brand: Microchip Technology
SKU: 24CS256-E/SM
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 24CS256-E/SM

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 8-SOIC (0.209", 5.30mm Width)

Datasheet:: 24CS256-E/SM.pdf

Description:: IC EEPROM 256KBIT I2C 1MHZ 8SOIJ

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Product details

Overview

24CS256-E/SM 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 operation from 1.7V to 5.5V. It features built-in ECC, a factory-programmed 128-bit serial number, and enhanced software write protection - deployed in automotive infotainment control modules for firmware parameter storage.

For engineers reviewing the 24CS256-E/SM datasheet, 24CS256-E/SM pinout, 24CS256-E/SM application, or 24CS256-E/SM equivalent, key selection criteria include High-Speed I²C support up to 3.4 MHz, AEC-Q100 qualification, dual write-protection modes (hardware WP pin + configurable zone locking), ECC-corrected reads, and extended temperature range (–40°C to +125°C).

Technical Context

The 24CS256-E/SM implements a two-wire I²C interface with Schmitt-trigger inputs and slope-controlled outputs to suppress ground bounce and noise. 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 user-lockable 64-byte ID page (0840h–087Fh).

Device behavior is modulated via three registers: Configuration register (enables enhanced software write protection per 32-Kbit zone), Security register (supports permanent lock of user ID page), and Manufacturer ID register (24-bit I²C-compliant ID). Write operations are internally self-timed, and the Error Correction State (ECS) latch signals when ECC corrects a single-bit error within a 4-byte readout.

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-aligned updates.
I²C Speed Modes	Up to 3.4 MHz High-Speed mode (2.5V–5.5V, Industrial temp); also supports 1 MHz / 400 kHz / 100 kHz - ensures compatibility across legacy and high-throughput host controllers.
Write Cycle Time	≤5 ms maximum for byte or page write - defines minimum inter-write latency; no external delay required beyond TWC completion.
Operating Voltage	1.7V to 5.5V - supports direct interfacing with 1.8V, 3.3V, and 5V microcontrollers without level shifters.
Temperature Range	–40°C to +125°C (Extended grade) - validated for under-hood automotive and industrial edge sensor nodes.
Endurance & Retention	1,000,000 write cycles; >200 years data retention at 55°C - guarantees long-term reliability in infrequent-update applications like calibration storage.
ECC Capability	Corrects up to one bit error per 4-byte readout; ECS latch flags correction events - improves system-level data integrity without host-side error handling overhead.

Pinout & Package

24CS256-E/SM is packaged in an 8-lead SOIJ (Small Outline J-Bend) with wettable flank leads, optimized for automated optical inspection (AOI) and high-reliability solder joint formation in automotive PCB assembly.

Pin/Terminal	Circuit Role	Design Meaning
A0	Hardware Address Input	LSB of 3-bit device address; hardwired to VSS or VCC to enable up to eight devices on same I²C bus - required for multi-node configurations (e.g., multiple ECUs sharing one bus).
A1	Hardware Address Input	Middle bit of 3-bit device address; sets unique client address alongside A0/A2 - essential for avoiding I²C address collisions in distributed systems.
A2	Hardware Address Input	MSB of 3-bit device address; determines full 7-bit I²C address (1010A2A1A0) - must be logic '0' in SOT-23 variants but fully functional in SOIJ.
VSS	Ground Reference	Primary return path for all internal circuitry and I/O; requires low-impedance connection to minimize noise coupling into SDA/SCL lines.
SDA	Serial Data Line	Bidirectional open-drain I²C data line; requires external pull-up resistor (330Ω for 3.4 MHz); changes only during SCL low - enforces strict I²C timing compliance.
SCL	Serial Clock Line	Input-only clock line synchronized to host controller; rise/fall times constrained (TR ≤1000 ns, TF ≤300 ns) to sustain 3.4 MHz operation.
WP	Hardware Write-Protect	Active-high pin that disables all writes to main array and Security register when tied to VCC - provides fail-safe protection during power-up or firmware update sequences.
VCC	Power Supply	1.7V–5.5V supply input; includes internal POR circuit with 1.5V threshold and 100 µs TPUP delay - ensures deterministic initialization before first I²C command.

Key Features

Feature	Design Value
Factory-Programmed 128-bit Serial Number	Uniquely identifies each unit across CS-series EEPROMs; eliminates need for post-manufacturing serialization in automotive Tier 1 production lines.
Enhanced Software Write Protection	Configurable via locked Configuration register to protect any of eight independent 32-Kbit zones - enables granular firmware parameter lockdown without hardware WP pin dependency.
I²C Manufacturer ID Function	Returns device-specific 24-bit ID on reserved host code (1111100x) - allows runtime identification and validation of 24CS256-E/SM presence in multi-vendor BOMs.
ESD Robustness	≥4000V HBM rating - ensures survival during handling and board-level integration in unshielded industrial environments.
Low-Power Operation	1 µA standby current at 5.5V (I-Temp); 5 µA at E-Temp - minimizes battery drain in always-on automotive modules with wake-on-I²C capability.

Applications

Automotive Body Control Module (BCM)	Industrial PLC Configuration Storage
Use Scenario: Storing calibrated sensor offsets, door lock actuator profiles, and lighting dimming curves across vehicle lifecycle. IC Role / Device Role / Timing Role: Nonvolatile parameter repository accessed via I²C during MCU boot and runtime reconfiguration; ECC ensures integrity of safety-critical calibration data. Use Value: Eliminates recalibration after battery disconnect; AEC-Q100 qualification and 125°C operation guarantee reliability in engine bay proximity mounting.	Use Scenario: Retaining ladder logic settings, I/O mapping, and communication protocol parameters across power cycles and firmware updates. IC Role / Device Role / Timing Role: Persistent configuration store interfaced by ARM Cortex-M7 PLC controller; 3.4 MHz I²C enables fast parameter reload during commissioning. Use Value: Reduces field service time by preserving machine-specific settings; software zone protection prevents accidental overwrite of critical operational parameters.
Medical Infusion Pump Calibration	Smart Energy Meter Firmware Metadata
Use Scenario: Securing pump delivery rate tables, motor torque compensation curves, and regulatory audit logs. IC Role / Device Role / Timing Role: Tamper-resistant storage element with lockable 64-byte ID page for cryptographic key binding and device attestation. Use Value: Meets IEC 62304 Class C software requirements via hardware-enforced write protection and ECC-corrected reads.	Use Scenario: Storing tariff schedules, meter firmware version history, and utility-specific security certificates in ANSI C12.22-compliant meters. IC Role / Device Role / Timing Role: Secure nonvolatile memory accessed over isolated I²C bus; Manufacturer ID register validates authentic Microchip component during anti-counterfeit checks. Use Value: Prevents unauthorized firmware modification via dual-layer protection (WP pin + software-configurable zone locks), satisfying UL 2900-1 cybersecurity requirements.

Automotive Body Control Module (BCM)

Industrial PLC Configuration Storage

Use Scenario: Storing calibrated sensor offsets, door lock actuator profiles, and lighting dimming curves across vehicle lifecycle.

IC Role / Device Role / Timing Role: Nonvolatile parameter repository accessed via I²C during MCU boot and runtime reconfiguration; ECC ensures integrity of safety-critical calibration data.

Use Value: Eliminates recalibration after battery disconnect; AEC-Q100 qualification and 125°C operation guarantee reliability in engine bay proximity mounting.

Use Scenario: Retaining ladder logic settings, I/O mapping, and communication protocol parameters across power cycles and firmware updates.

IC Role / Device Role / Timing Role: Persistent configuration store interfaced by ARM Cortex-M7 PLC controller; 3.4 MHz I²C enables fast parameter reload during commissioning.

Use Value: Reduces field service time by preserving machine-specific settings; software zone protection prevents accidental overwrite of critical operational parameters.

Medical Infusion Pump Calibration

Smart Energy Meter Firmware Metadata

Use Scenario: Securing pump delivery rate tables, motor torque compensation curves, and regulatory audit logs.

IC Role / Device Role / Timing Role: Tamper-resistant storage element with lockable 64-byte ID page for cryptographic key binding and device attestation.

Use Value: Meets IEC 62304 Class C software requirements via hardware-enforced write protection and ECC-corrected reads.

Use Scenario: Storing tariff schedules, meter firmware version history, and utility-specific security certificates in ANSI C12.22-compliant meters.

IC Role / Device Role / Timing Role: Secure nonvolatile memory accessed over isolated I²C bus; Manufacturer ID register validates authentic Microchip component during anti-counterfeit checks.

Use Value: Prevents unauthorized firmware modification via dual-layer protection (WP pin + software-configurable zone locks), satisfying UL 2900-1 cybersecurity 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 built-in ECC; no Security register; max I²C speed 1 MHz; 1.7V–5.5V; –40°C to +85°C only	Lacks serial number, zone-level write protection, and extended temperature support - suitable for cost-sensitive consumer electronics, not automotive.	Select only if ECC, AEC-Q100, or 125°C operation are unnecessary and legacy AT24C footprint compatibility is mandatory.
24AA256-I/SN	Same pinout; no ECC; no Security register; no High-Speed mode (max 400 kHz); 1.8V–5.5V; –40°C to +85°C	Missing 3.4 MHz interface, 128-bit serial number, and extended temp grade - limited to industrial control panels with relaxed timing and security needs.	Choose only for brownfield designs requiring drop-in replacement where 24CS256-E/SM's advanced features add no value.

Compared with AT24C256C-SSHL-T and 24AA256-I/SN, the 24CS256-E/SM delivers differentiated value through AEC-Q100 qualification, ECC-corrected reads, factory-unique serialization, and software-configurable 32-Kbit zone protection - making it the sole choice for safety- or security-critical automotive and medical deployments where data integrity is non-negotiable.

Availability

24CS256-E/SM is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC configuration storage, medical infusion pump calibration, smart energy meter firmware metadata, and industrial sensor node parameter retention requiring stable component supply across extended temperature and long product lifecycles.

Supply support for 24CS256-E/SM 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-E/SM belongs to Microchip's CS-series serial EEPROM family, designed specifically for automotive-grade reliability, enhanced security, and seamless integration into safety-critical embedded systems requiring certified nonvolatile memory with tamper resistance and long-term data integrity.

FAQ

What is the maximum I²C clock frequency supported by the 24CS256-E/SM?

The 24CS256-E/SM supports High-Speed I²C mode up to 3.4 MHz when operating at VCC ≥2.5V and within the Industrial temperature range (–40°C to +85°C). At lower voltages (1.7V–2.5V) or Extended temperature (–40°C to +125°C), the maximum clock frequency is 1 MHz. This dual-speed capability ensures backward compatibility while enabling faster configuration loads in modern host systems.

Does the 24CS256-E/SM require external pull-up resistors on SDA and SCL lines?

Yes, the 24CS256-E/SM requires external pull-up resistors on both SDA and SCL lines because its I²C interface uses open-drain outputs. Recommended values are 330Ω for 3.4 MHz operation, 2 kΩ for 1 MHz/400 kHz, and 10 kΩ for 100 kHz - selected based on bus capacitance and desired rise time. The device does not include internal pull-ups.

How is write protection implemented on the 24CS256-E/SM?

The 24CS256-E/SM implements dual-layer write protection: (1) Hardware-based via the WP pin (tie to VCC to disable all writes), and (2) Software-configurable via the locked Configuration register, which enables independent protection of any of eight 32-Kbit zones. Once locked, the Configuration register cannot be modified, ensuring persistent protection settings across power cycles.

What is the purpose of the Security register in the 24CS256-E/SM?

The Security register in the 24CS256-E/SM is a dedicated 1-Kbit area separate from main memory. It contains a factory-programmed, globally unique 128-bit serial number (read-only, addresses 0800h–080Fh) and a user-programmable, permanently lockable 64-byte ID page (addresses 0840h–087Fh). This enables secure device identification and irreversible storage of cryptographic keys or calibration signatures.

Is the 24CS256-E/SM pin-compatible with older Microchip EEPROMs like the 24LC256?

Yes, the 24CS256-E/SM is backward compatible with 24AA256/24LC256/24FC256 and AT24C256C in terms of pinout, basic I²C command set, and memory addressing - allowing direct substitution in existing designs. However, advanced features (ECC, Security register, enhanced write protection) require updated firmware to access and are not present in legacy parts.

24CS256-E/SM Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 8-SOIC (0.209", 5.30mm Width)

Packaging:: Tube

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:: 8-SOIJ

24CS256-E/SM FAQ

1.How can I place an order for 24CS256-E/SM through Aetrix?

Please submit a Request for Quotation (RFQ) for 24CS256-E/SM 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 24CS256-E/SM reliable?

The price and inventory of 24CS256-E/SM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 24CS256-E/SM is usually 5 days.

3.What payment methods are accepted for 24CS256-E/SM?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 24CS256-E/SM transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 24CS256-E/SM?

24CS256-E/SM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 24CS256-E/SM 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 24CS256-E/SM?

For technical support, including 24CS256-E/SM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 24CS256-E/SM requirements.

6.How does Aetrix verify that 24CS256-E/SM is sourced from the original manufacturer or authorized distributors?

All 24CS256-E/SM 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 24CS256-E/SM meets industry standards.

7.What is the process for return or replacement of 24CS256-E/SM?

All 24CS256-E/SM units undergo pre-shipment inspection (PSI). If there is an issue with 24CS256-E/SM, 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 24CS256-E/SM part is unused and in its original packaging.

Return procedure for 24CS256-E/SM:

1.Submit a request within 90 days.

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

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