4021BDM

Overview

The 4021BDM is an 8-bit static shift register manufactured by National Semiconductor. It functions as a parallel-to-serial converter featuring a synchronous serial data input, a clock input, and an asynchronous active HIGH parallel load input. The device includes eight asynchronous parallel data inputs and buffered parallel outputs derived from the last three stages. It is housed in a 16-pin ceramic DIP package with through-hole terminals, designed for military temperature ranges.

Feature Summary

• Provides parallel-to-serial conversion capability via synchronous serial data input and clock control.
• Features an asynchronous active HIGH parallel load input for immediate data capture.
• Includes buffered parallel outputs sourced from the final three internal stages.

Applications

• Data acquisition systems requiring parallel-to-serial interface conversion
• Military-grade digital logic circuits operating in extreme environments
• Embedded controller interfaces utilizing standard TTL/CMOS logic levels

Procurement Notes

Verify that the specific procurement lot matches the required military qualification standards, such as MIL-STD-883, given the component's classification. Confirm the package material is ceramic and the terminal finish meets the specified requirements for the intended application environment. Ensure the supplier provides traceability documentation consistent with the original National Semiconductor manufacturing records to guarantee authenticity and performance reliability.

Selection Notes

Select this component when an 8-bit parallel-to-serial conversion function is required within a military-grade specification. The ceramic DIP package offers superior thermal stability and hermetic sealing compared to plastic alternatives. Consider the asynchronous parallel load feature for applications demanding immediate data latching without waiting for a clock cycle. Verify compatibility with the system's voltage levels and clock frequencies against the official datasheet limits.

Part Context

This part belongs to the 4021 series of 8-bit static shift registers produced by National Semiconductor. It is distinct from other logic families due to its specific combination of asynchronous loading and buffered stage outputs. The 'BDM' suffix typically denotes the military grade and ceramic DIP packaging variant, differentiating it from commercial or plastic package versions available in the same functional family.

Replacement Considerations

Identify substitutes based on identical pinout, logic functionality, and military qualification standards. Cross-reference with other manufacturers offering 8-bit shift registers with asynchronous parallel load and buffered outputs. Ensure any replacement maintains the ceramic DIP form factor if environmental sealing is critical. Verify that the substitute component meets the same electrical specifications and temperature range requirements.