Microchip Technology 24CS256-I/P

Overview

24CS256-I/P from Microchip Technology is a 256-Kbit I²C serial EEPROM organized as 32,768 × 8-bit, featuring 3.4 MHz High-Speed mode support, built-in ECC for single-bit error correction, a factory-programmed 128-bit unique serial number, and dual write protection (hardware WP pin + software-configurable zone locking). It operates across 1.7V–5.5V and is AEC-Q100 qualified for automotive use.

For engineers reviewing the 24CS256-I/P datasheet, 24CS256-I/P pinout, 24CS256-I/P application, or 24CS256-I/P equivalent, key selection considerations include its 8-pin PDIP package with A0/A1/A2 address inputs, 5 ms max self-timed write cycle, 1 µA standby current at 5.5V, ECC latch reporting via Configuration register, and compatibility with legacy 24AA256/24LC256 devices in standard I²C systems.

Technical Context

The 24CS256-I/P implements a two-wire I²C interface with Schmitt-trigger inputs and slope-controlled outputs to suppress noise and ground bounce. 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 managed via three registers: Configuration register (enables enhanced software write protection per 32-Kbit zone and locks itself), Security register (supports irreversible ID page locking), and Manufacturer ID register (24-bit read-only value compliant with I²C ID protocol). Write operations are internally self-timed and disable all inputs during the 5 ms max cycle.

Key Specifications

Pinout & Package

24CS256-I/P uses an 8-lead PDIP package (0.300" wide) with through-hole mounting. Pin functions are electrically identical across all 8-pin variants (SOIC, MSOP, TSSOP, etc.), enabling drop-in replacement where footprint permits.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Compared with 24AA256-I/P and AT24C256C-PU-2.7, the 24CS256-I/P delivers measurable design advantages: ECC reduces field failure rates in EMI-prone environments, the 128-bit serial number cuts manufacturing line complexity, and 3.4 MHz I²C accelerates parameter loading-making it optimal for automotive, industrial, and regulated medical systems where reliability and traceability are mandatory.

Availability

24CS256-I/P is available at Aetrix Electronics and suitable for automotive body control units, industrial PLCs, smart appliance UI persistence, medical device calibration storage, and AEC-Q100-compliant embedded systems requiring stable component supply across long product lifecycles.

Supply support for 24CS256-I/P 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, FPGA, and memory solutions, serving automotive, industrial, communications, and consumer markets with vertically integrated silicon and development tools.

The 24CS256-I/P belongs to Microchip's CS-series serial EEPROM family, designed specifically to address automotive-grade reliability, secure device identity, and high-speed configurability in safety-critical and long-lifecycle embedded systems.

FAQ

What is the maximum I²C clock frequency supported by the 24CS256-I/P?

The 24CS256-I/P supports up to 3.4 MHz in High-Speed mode when VCC is 2.5V–5.5V and operating within the Industrial temperature range (-40°C to +85°C). At lower voltages (1.7V–2.5V) or Extended temperature range (-40°C to +125°C), the maximum clock frequency is 1 MHz. This dual-speed capability ensures compatibility with both legacy and high-throughput I²C hosts without redesign.

Does the 24CS256-I/P require external circuitry for I²C bus termination?

Yes, the 24CS256-I/P requires external pull-up resistors on both SDA and SCL lines. Recommended values are 10 kΩ for 100 kHz, 2 kΩ for 400 kHz/1 MHz, and 330 Ω for 3.4 MHz operation. The device's open-drain SDA output and Schmitt-trigger inputs are designed to work with these standard I²C bus conditions, and no additional filtering or buffering is needed for compliant implementations.

How does the built-in ECC in the 24CS256-I/P improve system reliability?

The 24CS256-I/P's ECC logic automatically detects and corrects single-bit errors within any 4-byte read window, and sets the Error Correction State (ECS) latch in the Configuration register to flag correction events. This eliminates silent data corruption in electrically noisy environments-such as automotive or industrial settings-without requiring host MCU intervention or additional software error-handling routines, directly improving functional safety and data integrity.

Can the 24CS256-I/P replace a 24LC256 in an existing design without modifications?

Yes, the 24CS256-I/P is backward compatible with the 24LC256 in standard-mode I²C operation (≤400 kHz), sharing identical pinout, memory map, and basic command set. However, to leverage its advanced features-including ECC, 128-bit serial number, and Enhanced Software Write Protection-firmware updates and optional WP pin reconfiguration may be required. No PCB changes are needed for drop-in replacement in legacy 24LC256 applications.

What is the purpose of the Security register in the 24CS256-I/P?

The Security register in the 24CS256-I/P is a dedicated 1-Kbit area separate from main memory, containing a factory-programmed 128-bit globally unique serial number (read-only, addresses 0800h–080Fh) and a user-programmable 64-byte ID page (addresses 0840h–087Fh) that can be permanently locked. This enables secure device identification, anti-cloning, and tamper-proof storage of cryptographic keys or calibration signatures without consuming main array space.