Microchip Technology 24LCS22A-I/SN

Overview

24LCS22A-I/SN from Microchip Technology Inc. is a 2 Kbit dual-mode serial EEPROM designed for VESA DDC/EDID applications in display systems. It operates in Transmit-Only (1 Kbit) and Bidirectional (2 Kbit) modes, supports I²C™ at up to 400 kHz, features hardware write-protection via WP pin and VCLK-level control, and delivers 1 mA active current at 5.5V for low-power monitor configuration storage.

For engineers reviewing the 24LCS22A-I/SN datasheet, 24LCS22A-I/SN pinout, 24LCS22A-I/SN application, or 24LCS22A-I/SN equivalent, key selection considerations include dual-mode clocking (VCLK for DDC1™, SCL for I²C™), flexible write-enable logic (VCLK high + WP state), E-EDID™ 1.3 compliance, 1,000,000 erase/write cycles, and industrial temperature operation from –40°C to +85°C.

Technical Context

The 24LCS22A-I/SN implements two independent serial protocols on shared SDA: a unidirectional DDC1™ mode synchronized to VCLK (rising-edge output, MSB-first, 8-bit bytes + null bit), and a bidirectional I²C™ mode using SCL with slave address 1010000x. Mode transition occurs only on valid SCL high-to-low edge followed by detection of its control byte - no software reset or power cycle required to enter Bidirectional mode once initiated.

Its internal architecture includes a 256 × 8-bit EEPROM array, page latches supporting up to eight-byte page writes, Schmitt-trigger inputs on SDA/SCL/VCLK for noise immunity, and a VCC threshold detector disabling write logic below 1.5V. Write protection is configurable: factory-default unlocked, enabled by writing any value to address 7Fh, then governed jointly by WP pin state and VCLK logic level per Table 6-1.

Key Specifications

Pinout & Package

24LCS22A-I/SN is housed in an 8-pin SOIC package (3.90 mm wide), RoHS-compliant and Pb-free, with standard pin pitch and footprint compatible with automated PCB assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24C02C-SSHM-T and ST M24C02-RMN6TP/K, the 24LCS22A-I/SN uniquely integrates hardware-level DDC1™ streaming and I²C™ bidirectional access in one die - eliminating external timing logic and reducing system-level validation effort for display interface compliance.

Availability

24LCS22A-I/SN is available at Aetrix Electronics and suitable for monitor EDID storage, DisplayPort sink configuration, KVM switch firmware retention, and digital signage controller setup requiring stable component supply across extended production lifecycles.

Supply support for 24LCS22A-I/SN 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, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24LCS22A-I/SN belongs to Microchip's VESA-compliant serial EEPROM product line, engineered specifically for display interface applications requiring dual-mode DDC/EDID functionality, industrial temperature resilience, and robust write-protection architecture.

FAQ

What is the primary function of the VCLK pin on the 24LCS22A-I/SN?

The VCLK pin serves two distinct roles: in Transmit-Only mode, it acts as the DDC1™ clock input - each rising edge clocks out one bit of EDID data on SDA; in Bidirectional mode, it functions as a write-enable control - a logic-high level is mandatory to permit write operations, regardless of WP pin state. This dual-role design enables seamless integration into VESA-compliant display systems without external mode-selection circuitry. The 24LCS22A-I/SN relies on VCLK timing to maintain strict DDC1™ protocol compliance during monitor enumeration.

How does the 24LCS22A-I/SN handle write protection, and what is the role of address 7Fh?

The 24LCS22A-I/SN implements a two-stage write-protection mechanism: initially unlocked (factory default), it becomes configurable only after any data is written to address 7Fh - this action sets an internal fuse that activates the WP pin. Once enabled, write access depends on both WP pin state (active-low) and VCLK logic level (must be high), as defined in Table 6-1. This architecture allows secure factory programming (WP = low) while preserving field-upgrade capability (WP = high, VCLK = high). The 24LCS22A-I/SN thus provides granular, hardware-enforced control over EDID modification in deployed systems.

Can the 24LCS22A-I/SN be used in systems operating at 3.3V, and what are the timing implications?

Yes, the 24LCS22A-I/SN operates across 2.5V to 5.5V, making it fully compatible with 3.3V systems. At 3.3V, its maximum I²C™ clock frequency is 100 kHz (per Table 1-2), with corresponding minimum THIGH/TLOW times of 4000 ns/4700 ns. Its VCLK timing remains valid down to 2.5V, supporting DDC1™ operation in low-voltage display interfaces. The 24LCS22A-I/SN maintains full functionality - including page writes, ACK polling, and noise immunity - across this voltage range, with no derating of endurance or retention specifications.

What happens if the 24LCS22A-I/SN loses power while in Bidirectional mode?

If power is removed while the 24LCS22A-I/SN is in Bidirectional mode, it automatically resets to Transmit-Only mode upon next power-up - this is the guaranteed initial state per the datasheet. No external reset signal or initialization sequence is required. The device begins streaming the first 1 Kbit (addresses 00h–7Fh) on SDA synchronized to VCLK, enabling immediate DDC1™-compliant monitor identification. The 24LCS22A-I/SN requires no stored mode state or nonvolatile configuration - its behavior is entirely determined by power-on conditions and subsequent SCL transitions.

Does the 24LCS22A-I/SN support page writes, and what is the maximum buffer size?

Yes, the 24LCS22A-I/SN supports page writes with an eight-byte internal buffer. Up to eight data bytes can be loaded into the buffer before issuing a Stop condition - the device then performs a self-timed internal write cycle to commit all bytes to EEPROM. Page boundaries align to 8-byte increments (e.g., addresses 00h–07h, 08h–0Fh), and crossing a boundary causes wraparound within the current page. This capability reduces I²C™ bus transactions during EDID block updates, improving efficiency versus single-byte writes. The 24LCS22A-I/SN guarantees atomic page writes - partial failures do not corrupt adjacent memory locations.