SN74HC166PWT

Shift Registers Overview

The SN74HC166PWT is an 8-bit parallel-load shift register from the Texas Instruments HC logic family, housed in a 16-pin TSSOP package. It operates within a supply voltage range of 2V to 6V and supports temperatures from -55°C to 125°C. The device features synchronous loading via the SH/LD input, serial shifting on the rising edge of the clock, and an asynchronous clear function. It provides push-pull outputs capable of driving up to 10 LSTTL loads with ±4mA drive at 5V.

Shift Registers Feature Summary

• Synchronous parallel data loading capability controlled by the SH/LD input pin
• Asynchronous direct overriding clear (CLR) input for immediate reset
• Gated clock inputs allowing CLK or CLK INH to enable shifting operations

Shift Registers Applications

• Increasing the number of inputs available to a microcontroller
• Parallel-to-serial data conversion
• Expanding I/O capabilities without requiring complex communication interfaces

Shift Registers Procurement Notes

Verify the specific suffix 'PW' corresponds to the TSSOP-16 package variant required for your PCB footprint. Confirm that the operating temperature range meets your environmental specifications, as revisions may affect maximum ratings. Ensure all unused inputs are terminated to VCC or GND to prevent undefined states.

Shift Registers Selection Notes

Select this component when a simple GPIO-controlled shift register is needed rather than a protocol-based expander. It is suitable for applications requiring fast parallel data capture and serial output transmission. Consider the 50pF capacitive load limit when designing output traces to ensure signal integrity.

Shift Registers Part Context

This part belongs to the SNx4HC166 family of 8-bit parallel-load shift registers manufactured by Texas Instruments. It utilizes standard CMOS technology with TTL-compatible inputs, allowing direct interfacing with legacy logic families while maintaining low power consumption characteristics typical of modern CMOS devices.

Shift Registers Replacement Considerations

SN74HC166DRG4

Shift Registers FAQ

How does the SH/LD input control the device mode?

When SH/LD is high, the device shifts data serially on the clock edge. When SH/LD is low, it synchronously loads data from the parallel inputs A through H.

What is the function of the CLK INH input?

CLK INH acts as a clock inhibit. Holding it high prevents clocking even if CLK is active. Holding it low enables the CLK input to trigger shifts.