Microchip Technology 24CS256-E/SN66KVAO

Overview

24CS256-E/SN66KVAO 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 AEC-Q100 qualification for automotive use in infotainment control modules.

For engineers reviewing the 24CS256-E/SN66KVAO datasheet, 24CS256-E/SN66KVAO pinout, 24CS256-E/SN66KVAO application, or 24CS256-E/SN66KVAO equivalent, key selection criteria include High-Speed I²C support up to 3.4 MHz, dual write-protection modes (hardware WP pin + software-configurable zone protection), extended temperature range (–40°C to +125°C), and 1-M-cycle endurance with >200-year data retention.

Technical Context

The 24CS256-E/SN66KVAO implements a two-wire I²C interface with Schmitt-trigger inputs, slope-controlled outputs, and configurable High-Speed mode (3.4 MHz at VCC ≥2.5V). Its memory architecture comprises a 256-Kbit main array and a separate 1-Kbit Security register containing a read-only 128-bit serial number and a user-lockable 64-byte ID page.

Device behavior is governed by three registers: Configuration (enabling enhanced software write protection across eight 32-Kbit zones), Security (for serialization and secure identity storage), and Manufacturer ID (24-bit I²C-compliant identifier). Write operations are internally self-timed, and ECC corrects single-bit errors within any four-byte readout, with an Error Correction State (ECS) latch indicating correction events.

Key Specifications

Pinout & Package

24CS256-E/SN66KVAO is packaged in an 8-lead UDFN (2 mm × 3 mm, wettable flank) with exposed pad. Pin functions are electrically identical across all 8-pin variants (SOIC, TSSOP, MSOP, VDFN), but physical layout matches UDFN top view.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24C256C-SSHL-T and 24AA256-I/SN, the 24CS256-E/SN66KVAO delivers higher reliability (ECC + 1M cycles), stronger security (factory serial number + lockable ID), and broader environmental capability (AEC-Q100, –40°C to +125°C), making it the only option qualified for next-generation automotive and industrial edge nodes.

Availability

24CS256-E/SN66KVAO is available at Aetrix Electronics and suitable for automotive infotainment systems, ADAS camera modules, and industrial PLCs requiring stable component supply, long-term lifecycle assurance, and AEC-Q100 compliance.

Supply support for 24CS256-E/SN66KVAO 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 components, and memory solutions, serving automotive, industrial, and communications markets with vertically integrated silicon and software.

The 24CS256 belongs to Microchip's CS-series serial EEPROM family, designed specifically for automotive and high-reliability industrial applications requiring enhanced security, extended temperature operation, and robust error resilience beyond standard EEPROM offerings.

FAQ

What is the package type and footprint of the 24CS256-E/SN66KVAO?

The 24CS256-E/SN66KVAO uses an 8-lead UDFN package (2 mm × 3 mm) with wettable flanks and an exposed pad. It shares pinout compatibility with other 8-pin variants (SOIC, TSSOP, VDFN), but the SN66KVAO suffix specifically denotes the UDFN-8 variant. The footprint requires solder paste stencil design accommodating the wettable flank geometry for automated optical inspection.

Does the 24CS256-E/SN66KVAO support both hardware and software write protection?

Yes, the 24CS256-E/SN66KVAO supports dual write-protection modes: hardware protection via the WP pin (active-high, disables all writes when tied to VCC), and enhanced software protection via the Configuration register, which allows independent locking of any of eight 32-Kbit memory zones. The Configuration register itself can be permanently locked after setup.

How does the built-in ECC in the 24CS256-E/SN66KVAO function during read operations?

The 24CS256-E/SN66KVAO applies ECC correction on every 4-byte readout, automatically detecting and correcting single-bit errors. When correction occurs, the read-only Error Correction State (ECS) latch in the Configuration register is set, allowing host firmware to log or respond to potential memory degradation before failure.

Is the 128-bit serial number in the 24CS256-E/SN66KVAO programmable or fixed at manufacture?

The 128-bit serial number in the 24CS256-E/SN66KVAO is factory-programmed, globally unique across the entire CS-series EEPROM family, and permanently read-only. It resides in the first 16 bytes of the Security register (address 0800h–080Fh) and cannot be altered, erased, or reprogrammed by the user.

What I²C clock frequencies does the 24CS256-E/SN66KVAO support, and what conditions enable 3.4 MHz operation?

The 24CS256-E/SN66KVAO supports I²C clock frequencies up to 3.4 MHz in High-Speed mode, enabled only when VCC is ≥2.5V and the device is operating in Industrial temperature range (–40°C to +85°C). At lower voltages or in Extended temperature range, maximum speed defaults to 1 MHz.

Can the 24CS256-E/SN66KVAO be used in place of the 24LC256 in existing designs?

The 24CS256-E/SN66KVAO is backward compatible with 24LC256 in pinout, basic command set, and voltage range, but adds High-Speed mode, ECC, Security register, and AEC-Q100 qualification. Migration requires verifying I²C timing margins at 3.4 MHz and confirming that firmware handles the ECS latch and enhanced protection modes.