Microchip 24LCS22A-I/SN: A Secure 2-Kbit I²C Serial EEPROM with Dual Software Write-Protect Pins

In the realm of embedded systems and IoT devices, the need for reliable, small-footprint, and secure non-volatile memory is paramount. The Microchip 24LCS22A-I/SN addresses these requirements by offering a robust 2-Kbit serial EEPROM memory that combines the ubiquitous I²C interface with advanced hardware and software security features. This device is engineered for applications where data integrity and controlled access are critical.

At its core, the 24LCS22A provides 2048 bits of Electrically Erasable PROM (EEPROM) organized as 256 x 8 bits. This capacity is ideal for storing crucial but small datasets such as device configuration parameters, calibration constants, serial numbers, and usage logs. The memory array is guaranteed to withstand 1,000,000 erase/write cycles and offers 200-year data retention, ensuring long-term reliability for the life of the end product.

The device communicates via a two-wire I²C serial interface, supporting clock frequencies up to 400 kHz. This standard protocol simplifies design-in, reduces board space by minimizing interconnect lines, and allows the memory to share the bus with other compatible peripherals. Eight different I²C slave addresses are available, enabling up to eight of these devices to coexist on the same bus, providing effective memory expansion.

The defining feature of the 24LCS22A is its sophisticated write-protection scheme. While many EEPROMs offer a single hardware write-protect pin, this device enhances security with dual software write-protect pins (A and B). The state of these two pins is not just a simple hardware override; it is digitally latched on the falling edge of a STOP condition or when power is removed. This latched state is then used in conjunction with internally programmed registers to create a highly flexible protection system.

The protection logic is controlled via two One-Time Programmable (OTP) non-volatile registers: the Block Protection Register and the Pin Access Register. This system allows the memory array to be partitioned into four 64-byte blocks, each of which can be individually set to be permanently write-protected or protected based on the specific logic state of the two software write-protect pins. This granularity allows designers to create a precise security policy, locking down sensitive firmware or data while leaving other sections available for routine updates.

Housed in an space-efficient 8-lead SOIC (SN) package, the 24LCS22A operates across an industrial temperature range of -40°C to +85°C, making it suitable for a wide array of demanding environments. Its low power consumption further enhances its suitability for battery-powered applications.

ICGOOODFIND: The Microchip 24LCS22A-I/SN stands out as a highly secure and reliable solution for low-density non-volatile memory needs. Its innovative use of dual software write-protect pins, combined with OTP block protection registers, provides an unparalleled level of flexible security for sensitive data, making it an excellent choice for secure IoT nodes, medical devices, industrial controls, and consumer electronics.

Keywords: I²C EEPROM, Write-Protect, Non-Volatile Memory, Data Security, Embedded Systems.