4556BDM

Overview

The National Semiconductor 4556BDM is a dual timer integrated circuit belonging to the CMOS logic family. It integrates two independent timer circuits within a single ceramic dual in-line package (DIP) featuring sixteen pins. The device operates as a decoder or demultiplexer with a 2-to-4 line configuration, utilizing standard CMOS technology. It is designed for military-grade applications, supporting an extended temperature range from -55°C to 125°C and powered by supply voltages of 5V or 15V.

Feature Summary

• Dual timer architecture providing two independent timing functions
• CMOS technology ensuring low power consumption
• Military-grade qualification for harsh environments
• Ceramic DIP packaging for robust physical protection

Applications

• Military electronic systems requiring high reliability
• Industrial control logic and timing sequences
• Telecommunications equipment operating in extreme temperatures
• Aerospace instrumentation and signal processing

Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels. Confirm that the ceramic package matches the specified MIL-spec requirements. Check for RoHS compliance status, as indicated by non-compliant certification data. Ensure storage conditions prevent moisture damage to the ceramic housing before installation.

Selection Notes

Select this component when dual independent timers are required in a ruggedized environment. The ceramic DIP package offers superior thermal stability compared to plastic variants. Consider the specific voltage requirements of 5V or 15V during system design. Evaluate the need for military-grade temperature ranges versus commercial alternatives.

Part Context

National Semiconductor, now part of Texas Instruments, specializes in analog and mixed-signal integrated circuits. The 4556 series represents a legacy line of CMOS logic devices known for reliability. This specific model serves niche markets where traditional bipolar timers are insufficient due to power or environmental constraints.

Replacement Considerations

Compatible substitutes include the NE556BD and LM556BD. Verify pin compatibility and electrical specifications before substitution. Ensure the replacement maintains the same ceramic DIP package and military temperature rating.