Microchip Technology AT28C64B-15JU-235

Introduction to AT28C64B-15JU-235 Microchip Technology EEPROM

The AT28C64B-15JU-235 from Microchip Technology is a robust 64Kbit parallel EEPROM memory IC designed for high-speed, reliable nonvolatile storage in demanding electronic systems. Organized as 8,192 words by 8 bits, it is built on advanced CMOS technology to deliver a seamless interface for both designers and procurement engineers seeking proven, low-power memory solutions. The device is available in a JEDEC 32-lead PLCC package (11.43x13.97mm), compatible with industry-standard footprints for easy integration into legacy and new designs.

Main Attributes of the AT28C64B-15JU-235 Series

The AT28C64B-15JU-235 is engineered for high-speed memory operations, featuring fast access times of 150ns and optimal write cycle efficiency. Its internal address and data latches support single-byte and page write operations of up to 64 bytes—dramatically expediting data throughput in scenarios like firmware upgrades and industrial logging. Power considerations are addressed through a low active current of 40mA and a standby current below 100μA in CMOS mode, making it an ideal candidate for battery-powered systems or energy-sensitive applications.

Hardware and software data protection mechanisms are integrated to safeguard against inadvertent programming, a critical need in industrial automation, medical instrumentation, and mission-critical control systems. The device provides reliability through CMOS process advantages, supporting 100,000 write cycles endurance and guaranteeing data retention for 10 years. The AT28C64B-15JU-235 operates from a single +5V ±10% supply, with TTL and CMOS-compatible inputs/outputs, and supports industrial temperature ranges with halide-free “green” packaging for applications with environmental compliance requirements.

AT28C64B-15JU-235 Pin Layout and Packaging Variants

For engineers specifying layout and assembly, the AT28C64B-15JU-235 supports a variety of package options including 32-lead PLCC, 28-lead PDIP, SOIC, and TSOP. The JEDEC-approved pinout simplifies prototyping and manufacturing by supporting common industry standards. Top view diagrams illustrate the placement and handling for each package, with “Don’t Connect” pins clearly marked to prevent design errors. Dimensional tolerances and coplanarity specifications ensure reliable mounting in automated assembly lines.

Operating Principles Read, Write, and Page Write Functions

The operational paradigm of the AT28C64B-15JU-235 mirrors that of static RAM, simplifying memory access cycles and software development. Read operations are enabled when both chip enable and output enable signals are low, providing immediate data throughput and allowing designers to optimize for minimal bus contention in microprocessor-based designs.

Write operations are flexible—supporting both single-byte and multi-byte (page) writes. Byte writes are initiated via the chip enable or write enable signal transitions, latching both address and data for error-free programming. The page write function is especially beneficial in embedded systems or batch data logging, allowing up to 64 bytes to be programmed in one cycle with strict timing. Addressing is handled with A6–A12 for page selection and A0–A5 for byte specification within the page, enabling random-access loads which maximize efficiency in firmware updates and iterative parameter storage.

To inform the system when programming is complete, the AT28C64B-15JU-235 provides two polling mechanisms: data polling and toggle bit monitoring, which let system software verify readiness before starting new cycles. Detailed AC waveforms and timing diagrams in the datasheet support deeper integration and timing analysis.

Data Reliability and Protection Features in AT28C64B-15JU-235

Recognizing the importance of data integrity in unpredictable operational environments, the AT28C64B-15JU-235 incorporates sophisticated data protection schemes. Hardware protection blocks programming if the Vcc drops below 3.8V or during power supply transitions, preventing errant writes. Input noise is filtered at the hardware level, ignoring pulses shorter than 15ns to minimize inaccuracies caused by noisy supply rails or signal glitches.

Software data protection (SDP) can be enabled and disabled by custom command sequences, giving engineers control over inadvertent writes during critical phases like field updates, manufacturing or calibration. Once enabled, writes require a specific 3-byte sequence for access, with SDP maintained across power-up and power-down transitions. For environments where memory reliability must be paramount, such as industrial machinery or aerospace controllers, these layered safeguards are essential.

AT28C64B-15JU-235 Device Marking and Engineering Traceability

The AT28C64B-15JU-235 officially supports an additional set of 64-bytes of EEPROM, mapped for device identification or lifecycle tracking. This feature is accessed by raising the A9 pin to 12V, allowing storage of asset numbers, manufacturing codes, calibration data, or revision history—features which are increasingly required for traceability in medical, automotive, and safety-critical industrial sectors.

Electrical Specifications and Operating Parameters for AT28C64B-15JU-235

Engineers must carefully consider the electrical performance envelope of any nonvolatile memory device. The AT28C64B-15JU-235 is rated for stable operation between -55°C and +125°C (bias), and storage from -65°C to +150°C. All input and output voltage ranges are specified in detail, with careful attention to absolute maximums to preserve device longevity and reliability. DC performance metrics indicate robust operation, while AC characteristics and detailed timing diagrams enable accurate design of synchronous and asynchronous interfaces.

Physical and Environmental Ratings of the AT28C64B-15JU-235 Series

Physical integration is supported by extensive package documentation for PLCC, PDIP, SOIC, and TSOP variants, each conforming to JEDEC standards. Controlled lead coplanarity and dimensional tolerances facilitate automated pick-and-place assembly, critical for volume production and reflow soldering. The “green” package option ensures compliance with RoHS and halide-free requirements, supporting deployment in regions and markets with strict material regulations.

Alternative or Substitute Devices for AT28C64B-15JU-235

For procurement and engineering teams seeking alternates or drop-in replacements, the AT28C64B-15JU-235 belongs to a class of parallel EEPROMs such as AT28HC64BF (featuring a faster page write cycle) and other 8K x 8 EEPROM ICs from Microchip Technology and legacy Atmel lines. When evaluating replacements, considerations include write endurance, retention specs, access times, SDP availability, and exact pin compatibility, particularly for upgrades and maintenance scenarios in long-lived industrial platforms.

Conclusion

: AT28C64B-15JU-235 as a reliable choice for parallel EEPROM memory

The Microchip AT28C64B-15JU-235 stands out as a well-engineered, reliable parallel EEPROM suited for a wide range of demanding electronic systems, from industrial controls and medical equipment to legacy upgrades in data logging and programmable logic. With high-speed access, robust data protection, flexible page write architecture, and comprehensive package support, it provides a secure and cost-effective memory solution, meeting the technical needs and compliance demands of modern electronic product development.