24LC21A/P

Memory IC Overview

The Microchip Technology 24LC21A/P is a 128 x 8-bit dual-mode Electrically Erasable PROM designed for configuration and control information storage. It operates on a single supply voltage ranging from 2.5V to 5.5V with low-power CMOS technology, featuring typical active current of 1 mA and standby current of 10 μA at 5.5V. The device supports a 2-Wire Serial Interface Bus compatible with I²C™, offering clock frequencies of 100 kHz at 2.5V and 400 kHz at 5V. It includes self-timed write cycles, an eight-byte page write buffer, and ensures 1,000,000 erase/write cycles with data retention exceeding 200 years. The component is housed in an 8-pin PDIP package.

Memory IC Feature Summary

• Implements DDC1/DDC2 interface standards for monitor identification, including recovery to DDC1 mode
• Features dual operation modes: Transmit-Only for continuous serial bit stream output and Bidirectional for standard I²C read/write access
• Includes hardware write-protect capability via the VCLK pin to prevent unintended memory array modifications
• Provides ESD protection greater than 4000V and utilizes Schmitt Trigger inputs for noise suppression

Memory IC Applications

• Monitor identification and EDID storage compliant with VESA Display Data Channel (DDC) standards
• Configuration and control information storage in embedded systems requiring non-volatile memory
• Bidirectional data transmission applications utilizing standard I²C bus protocols

Memory IC Procurement Notes

Verify that the specific ordering suffix '/P' corresponds to the 8-pin PDIP package type as indicated by the manufacturer's designation. Confirm the temperature grade matches the required operational environment, noting that industrial variants are available. Ensure compatibility with the system's power supply range of 2.5V to 5.5V and verify that the I²C bus timing requirements align with the specified clock frequencies for the target voltage.

Memory IC Selection Notes

Select this component when application requirements necessitate compliance with VESA DDC standards for display identification alongside standard I²C communication capabilities. The dual-mode architecture allows seamless transition between unidirectional data streaming and bidirectional read/write operations based on bus signaling. Consider the 8-pin PDIP package for through-hole mounting requirements and ensure the design accommodates the necessary pull-up resistors for the SDA and SCL lines.

Memory IC Part Context

The 24LC21A belongs to the 24LC series of serial EEPROMs manufactured by Microchip Technology. This series is characterized by low-voltage operation and I²C compatibility. The 'A' suffix typically denotes revisions or enhancements over previous iterations, while the '/P' suffix specifically identifies the plastic dual in-line package variant. It serves as a successor or alternative to earlier models like the 24LC21, maintaining pin and function compatibility.

Memory IC Replacement Considerations

The datasheet explicitly states the device is pin and function compatible with the 24LC21.