Microchip Technology 24LC22A-I/P

Overview

24LC22A-I/P 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 mode (1 Kbit, VCLK-clocked) and Bidirectional I²C mode (2 Kbit, SCL-clocked), supports 2.5–5.5V supply, delivers 1 mA active current, and features 1,000,000 erase/write cycles with >200-year data retention.

For engineers reviewing the 24LC22A-I/P datasheet, 24LC22A-I/P pinout, 24LC22A-I/P application, or 24LC22A-I/P equivalent, this page provides verified functional modes, VCLK/SCL dual-clock timing constraints, write-protection via VCLK logic level, E-EDID™ 1.3 compliance, and industrial-grade (-40°C to +85°C) operation in PDIP package.

Technical Context

The 24LC22A-I/P implements two independent serial protocols on shared SDA: Transmit-Only mode uses VCLK for unidirectional EDID streaming (address 00h–7Fh), while Bidirectional mode uses SCL for full 2 Kbit I²C read/write access with slave address 1010000x. Mode transition requires a valid high-to-low SCL edge followed by detection of its control byte.

Write enable is strictly gated by VCLK = high in Bidirectional mode; pulling VCLK low disables all writes, enabling ROM-like operation. Internal address pointer auto-increments during sequential reads, and page-write buffer holds up to eight bytes within a single 8-byte physical page boundary - crossing boundaries causes wraparound, not page advancement.

Key Specifications

Pinout & Package

24LC22A-I/P is supplied in an 8-pin Plastic Dual In-line Package (PDIP) with 300-mil body width. Pin 1 is bottom-left corner when notch faces up; pins 1–4 are left side, 5–8 right side.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC22A-I/P, the 24LC21A-I/P sacrifices bidirectional programmability for lower cost and identical EDID compatibility, while the AT24C256-10PU-2.7 offers vastly greater density but removes hardware-level EDID streaming - making it incompatible with DDC1-only hosts.

Availability

24LC22A-I/P is available at Aetrix Electronics and suitable for monitor manufacturing, industrial HMI development, and broadcast equipment design requiring stable component supply with guaranteed long-term availability and RoHS-compliant sourcing.

Supply support for 24LC22A-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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and memory solutions for industrial, automotive, and consumer applications.

The 24LC22A-I/P belongs to Microchip's legacy serial EEPROM product line, engineered specifically for VESA DDC/EDID compliance in display interfaces - balancing low-power operation, dual-mode flexibility, and robust noise immunity for real-world video subsystems.

FAQ

What are the two operational modes of the 24LC22A-I/P and how do they differ?

The 24LC22A-I/P operates in Transmit-Only mode (1 Kbit, VCLK-clocked EDID streaming) and Bidirectional mode (2 Kbit, SCL-clocked I²C read/write). Power-up defaults to Transmit-Only; a valid SCL edge triggers transition to Bidirectional mode, which persists until power cycle. The 24LC22A-I/P uses distinct clock inputs (VCLK vs. SCL) and separate protocols - no software or register configuration is needed to switch modes.

How does VCLK function in Bidirectional mode of the 24LC22A-I/P?

In Bidirectional mode, VCLK serves solely as a hardware write-enable control: it must be held high to permit any write operation (byte or page), and pulled low to disable all writes - effectively converting the 24LC22A-I/P into a read-only device. VCLK is ignored during the self-timed write cycle itself, and changing its state mid-program has no effect on ongoing writes.

Can the 24LC22A-I/P be used in systems requiring only DDC1 compatibility?

Yes - the 24LC22A-I/P fully supports DDC1™ via its Transmit-Only mode, streaming the first 128 bytes (00h–7Fh) continuously on SDA synchronized to VCLK. This mode requires no I²C master interaction and is compatible with legacy graphics controllers that lack DDC2B support. The 24LC22A-I/P meets all VESA DDC Standard timing and electrical requirements for DDC1 operation.

What is the maximum page-write size supported by the 24LC22A-I/P?

The 24LC22A-I/P supports up to eight bytes per page-write operation, constrained by its on-chip page buffer. Physical page boundaries align every 8 bytes (0x00–0x07, 0x08–0x0F, etc.). Attempting to cross a boundary causes wraparound within the current page - for example, writing nine bytes starting at 0x07 stores bytes 1–8 at 0x07–0x0E and byte 9 overwrites 0x07. The 24LC22A-I/P does not auto-advance across pages.

Does the 24LC22A-I/P require external pull-up resistors on its bus lines?

Yes - the SDA and SCL pins are open-drain outputs and require external pull-up resistors to VCC. Recommended values are 10 kΩ for 100 kHz operation and 2 kΩ for 400 kHz. VCLK is a CMOS input and does not require a pull-up. Pull-up placement should minimize trace capacitance to meet rise-time specs (TR ≤ 1000 ns at 2.5V).