The Microchip AT28C64B-15JU-T: A Robust Parallel EEPROM for Demanding Applications

In the realm of non-volatile memory, parallel EEPROMs have long been the workhorses for systems requiring reliable, byte-alterable storage with a simple, fast interface. The Microchip AT28C64B-15JU-T stands as a prime example of this enduring technology, offering a robust 64Kbit memory solution for a wide array of industrial, automotive, and consumer applications.

This integrated circuit organizes its 65,536 bits as 8,192 words by 8 bits (8K x 8), providing a convenient byte-wide architecture that simplifies data handling with common 8-bit and 16-bit microcontrollers. The device is designed for high-performance parallel data access, a key advantage over slower serial EEPROMs when read speed is critical. The part number suffix -15 denotes a maximum access time of 150ns, enabling fast read operations that can keep pace with demanding processors without introducing significant wait states.

A critical feature of the AT28C64B is its advanced data protection circuitry. This includes both hardware and software data protection mechanisms to prevent inadvertent write cycles. A `WE` (Write Enable) controlled write cycle and a dedicated `OE` (Output Enable) pin ensure glitch-free operation. Furthermore, it incorporates optional software data protection, which, when enabled, requires a specific three-byte command sequence to initiate a write, safeguarding memory contents from errant code execution.

The device supports a standard +5V power supply and is specified for operation over the industrial temperature range (-40°C to +85°C), as indicated by the -JU package suffix for the 32-lead PLCC. It features a 64-byte page write mode, allowing for more efficient programming by writing up to 64 bytes of data in a single cycle, significantly reducing firmware update times compared to single-byte writes. With an endurance of 10^4 write cycles per byte and data retention of 10 years, it provides the reliability necessary for long-term product lifecycles.

ICGOOODFIND: The Microchip AT28C64B-15JU-T remains a highly reliable and performant choice for designers seeking a proven parallel EEPROM solution. Its combination of fast access times, robust data protection features, and high endurance makes it exceptionally well-suited for legacy system support, firmware storage, and data logging in critical environments where reliability cannot be compromised.

Keywords: Parallel EEPROM, Non-volatile Memory, Data Protection, Page Write Mode, 150ns Access Time.