Microchip Technology AT28C64B-15TU

Summary of the AT28C64B-15TU by Microchip Technology

The AT28C64B-15TU, manufactured by Microchip Technology, is a 64Kbit (8K x 8) parallel Electrically Erasable Programmable Read-Only Memory (EEPROM) device designed for high-reliability, high-speed nonvolatile data storage. Intended for industrial applications requiring robust and flexible program/data retention, the AT28C64B-15TU leverages advanced CMOS technology to deliver low power consumption, fast access times, and simple integration into a wide range of electronic systems. Packaged in a 28-lead TSOP (Thin Small Outline Package) with a width of 11.80mm, this EEPROM is optimized for space-sensitive surface mount designs.

Main Characteristics and Advantages of the AT28C64B-15TU

The AT28C64B-15TU offers an array of features aimed at enhancing system performance and data integrity. It supports high-speed read access with a typical address-to-output delay of 150ns, making it suitable for performance-critical embedded systems. A 64-byte internal page register allows for efficient page write operations, with standard and fast write cycle time options (down to 2ms for select variants). Integrated hardware and software data protection mechanisms prevent inadvertent data corruption, especially during power cycling or transient noise events. The device also provides two user-friendly methods for write completion detection: DATA Polling on I/O7 and Toggle Bit monitoring on I/O6. These features facilitate straightforward firmware implementation and robust end-of-write management.

A key benefit of the AT28C64B-15TU is its long-term reliability, with an endurance of 100,000 program/erase cycles per location and a data retention expectation exceeding 10 years. Power efficiency is another highlight, with a maximum active current of 40mA and CMOS standby current as low as 100μA, making it suitable for both battery-powered and always-on applications.

Internal Design and Working Principle of the AT28C64B-15TU

The AT28C64B-15TU operates with an interface and access protocol that closely resemble static RAM, simplifying its integration into microprocessor-based designs. Read cycles are initiated by placing both the Chip Enable (CE) and Output Enable (OE) signals low, with Write Enable (WE) held high. For data writing, either a byte or page write operation can be performed: a write cycle is triggered by applying low pulses to the CE or WE pins with appropriate logic levels on OE and data/address lines. The device then internally latches addresses and up to 64 bytes of data, freeing the bus for other activity during internal programming.

In-system data protection is a critical design aspect. Hardware protection includes VCC sensing to inhibit writes below 3.8V, power-on write delay, write inhibit controls, and on-chip noise filtering to reject spurious write pulses. Additionally, an optional software data protection scheme can be enabled by command sequence, effectively locking out accidental writes without impacting normal operation. The AT28C64B-15TU also features a separate 64-byte Ident Memory Section for device identification or tracking, accessible via a dedicated address range and voltage protocol.

Technical Performance and Reliability Metrics for the AT28C64B-15TU

Within the industrial temperature range of -40°C to +85°C, the AT28C64B-15TU functions reliably from a single 5V ±10% supply. It offers fast access and cycle times—address-to-output delay at 150ns, page write completion in as little as 10ms (2ms for specific fast variants), and rapid input/output signal transitions. The device’s electrical parameters are compliant with both CMOS and TTL logic levels, allowing seamless interface with contemporary logic families.

The device stands out for high write cycle endurance (100,000 cycles minimum per memory address) and 10-year data retention, ensuring suitability for mission-critical systems. It is RoHS 3 compliant and rated moisture sensitivity level (MSL) 3 for surface-mount manufacturing.

Packaging, Pin Configuration, and System Integration Information for the AT28C64B-15TU

The AT28C64B-15TU is supplied in a 28-lead TSOP package with a 0.465" (11.80mm width), conforming to JEDEC standards for byte-wide EEPROM pinouts. This form factor is particularly advantageous for surface-mount applications requiring high-density memory with minimal board footprint. The TSOP package facilitates automated optical inspection and high-volume SMT production lines.

Functional pin assignments cover address inputs (A0-A12), data input/outputs (I/O0–I/O7), and standard control signals (CE, WE, OE), following a widely-used pinout which eases replacement or upgrade planning. The device also features extra protections such as NC (no connect) and DC (don’t connect) pins for integrity in PCB layout and future design flexibility.

Use Cases and Design Notes for the AT28C64B-15TU

The robust design and operational features of the AT28C64B-15TU position it as an ideal solution for industrial control, system firmware storage, configuration tables, calibration data, and device serial numbers. Real-world scenarios include embedded controllers requiring field re-programmability, digital instrumentation needing reliable data logging, or any application that cannot tolerate accidental data loss during power spikes or brownouts.

When engineering systems with the AT28C64B-15TU, attention must be paid to the implementation of proper decoupling for VCC, adherence to recommended signal timing, and enabling optional software data protection where the use environment is prone to inadvertent signal glitches. Its compatibility with both 5V CMOS and TTL logic, as well as its JEDEC-standard pinout, ensures adaptability in upgrades and multi-vendor supply chains.

Alternative or Replacement Options for the AT28C64B-15TU

Given that the AT28C64B-15TU is classified as an obsolete product, engineers and procurement specialists may seek drop-in replacements or functionally similar memories. Suitable alternatives may include other 64Kbit parallel EEPROMs with comparable access times, pinouts, and voltage ranges, such as Microchip’s AT28C64B-15PC or AT28C64B-15SC in different packages, or compatible devices from other established manufacturers. When evaluating replacements, it is essential to confirm package compatibility, memory organization (8K x 8), electrical characteristics, and support for data protection features to ensure seamless migration and avoid system-level redesigns.

Conclusion

: Selecting AT28C64B-15TU for modern memory requirements

The AT28C64B-15TU from Microchip Technology remains a reference point for reliable, high-speed parallel EEPROMs, thanks to its robust data protection, fast access, and industrial-grade reliability. For engineers specifying memory in industrial, embedded, or high-reliability sectors, this device encapsulates a compelling balance of performance and durability. While the AT28C64B-15TU’s obsolescence status necessitates consideration of equivalent models for new designs, its architecture and broad feature set provide a sound benchmark for selecting replacement EEPROM solutions.