SN74ALS166DB

Shift Registers Overview

The SN74ALS166DB is a parallel-load 8-bit shift register from the Texas Instruments ALS logic family, housed in a 16-pin Shrink Small-Outline (SSOP) package. It operates within a supply voltage range of 4.5 V to 5.5 V and supports an operating temperature range of 0°C to 70°C. The device features buffered inputs with clamping diodes, synchronous loading via the SH/LD pin, and an overriding asynchronous clear (CLR). Clocking utilizes a two-input positive-NOR gate for CLK and CLK INH, enabling flexible clock control. Maximum clock frequency reaches 45 MHz, with propagation delays ranging from 2 ns to 14 ns depending on the signal path.

Shift Registers Feature Summary

• Supports parallel-to-serial conversion through gated clock inputs and a synchronous load function controlled by the SH/LD input.
• Features an overriding asynchronous clear (CLR) input that sets all flip-flops to zero regardless of other active signals.
• Incorporates buffered inputs with integrated clamping diodes to minimize switching transients and reduce system drive requirements.

Shift Registers Applications

• Parallel-to-serial data conversion circuits
• Serial-in or serial-out shift register configurations
• Synchronous data storage and processing systems

Shift Registers Procurement Notes

Verify the specific ordering suffix 'DB' corresponds to the SSOP package variant when sourcing. Confirm RoHS compliance status and lead finish details against the latest TI Package Option Addendum. Ensure the procurement channel provides valid traceability documentation for production-grade components. Cross-reference the part marking 'G166' to validate authenticity upon receipt.

Shift Registers Selection Notes

Select this component for applications requiring high-speed serial shifting within standard TTL-compatible voltage levels. The ALS series offers faster switching speeds compared to standard LS logic while maintaining lower power consumption than full-speed variants. Consider the SSOP package dimensions for space-constrained printed circuit board layouts where surface-mount assembly is preferred over through-hole technology.

Shift Registers Part Context

This device belongs to the SN74ALS166 family of parallel-load 8-bit shift registers manufactured by Texas Instruments. It is designed to be compatible with most other TTL logic families, facilitating integration into mixed-logic systems. The DB suffix specifically denotes the shrink small-outline package configuration, distinguishing it from standard SOIC or PDIP variants within the same functional family.

Shift Registers Replacement Considerations

SN74ALS166DR

Shift Registers FAQ

How does the SN74ALS166 handle clock inhibition?

Clocking is managed through a two-input positive-NOR gate accepting CLK and CLK INH signals. Holding either input high inhibits clocking, while holding either low enables the other input, allowing the register to stop on command even if the system clock is free-running.

What is the function of the SH/LD input?

The SH/LD input determines the operational mode. When high, it enables serial data flow for shifting. When low, it disables serial data and enables synchronous loading of the parallel inputs (A–H) onto the flip-flops at the next clock pulse.