MR8254/B

Overview

The MR8254/B is a high-performance CMOS Programmable Interval Timer manufactured by Rochester Electronics, LLC. It serves as an enhanced version of the NMOS 8253 and maintains compatibility with industry-standard NMOS 8254 devices. The component features three independently programmable 16-bit counters capable of handling clock input frequencies up to 12MHz. Designed for harsh environments, it meets MIL-STD-883 standards and QML Class Q military qualification. The device utilizes an advanced 2-micron CMOS process to ensure reliable operation across a temperature range of -55°C to +125°C.

Feature Summary

• Three independent 16-bit counters with clock inputs up to 12MHz
• Compatible with Intersil 80C86, 80C88, and 80C286 microprocessors
• Six programmable timer modes for flexible configuration
• QML Class Q (military) qualification under MIL-STD-883

Applications

• Military-grade timing and counting applications
• Harsh environment industrial control systems
• Compatibility with legacy 80C86/80C88/80C286 processor architectures

Part Context

Rochester Electronics specializes in sourcing and distributing obsolete and hard-to-find semiconductors. The MR8254/B represents a continuation of support for legacy Intersil components, specifically providing a CMOS alternative to older NMOS designs like the 8253. This part ensures availability for existing military and industrial designs requiring specific timing functionalities without redesigning the core logic.

Replacement Considerations

The MR8254/B is functionally equivalent to the Intersil 82C54/B. Designers should verify that the 12MHz maximum clock frequency meets system requirements compared to lower-speed variants. Ensure the CERDIP package dimensions and pinout match the original PCB layout.