NXP 74LV164PW: 8-Bit Serial-In/Parallel-Out Shift Register - Datasheet Overview and Application Notes

The NXP 74LV164PW is a high-performance, low-voltage 8-bit serial-in/parallel-out shift register belonging to NXP's extensive 74LV family of logic devices. Housed in a TSSOP-14 package, this IC is engineered for space-constrained applications requiring efficient data conversion and expansion of I/O capabilities. Its low-voltage operation makes it particularly suitable for interfacing with modern microcontrollers and digital systems.

A primary function of the 74LV164PW is to convert serial data input into a parallel 8-bit output. It features two serial data inputs (DSA and DSB) that are ANDed together internally, providing flexibility for data gating or enabling. Data is shifted through the register on the low-to-high transition of the clock pulse (CP). A Master Reset (MR) pin, when held low, clears the entire register asynchronously, forcing all outputs (Q0 to Q7) to a low state regardless of the clock or data inputs, which is crucial for system initialization.

Key electrical characteristics from its datasheet include a wide operating voltage range from 1.0 V to 5.5 V, allowing for seamless integration into both 3.3V and 5V systems. It boasts a high noise immunity and low power consumption, typical of CMOS technology. The outputs can sink up to 8 mA, enabling them to drive LEDs or other small loads directly.

Typical applications for this shift register are diverse. It is extensively used for I/O port expansion on microcontrollers (MCUs), where a few GPIO pins can control numerous outputs. This is ideal for driving LED displays, seven-segment arrays, or controlling multiple relays and actuators. It also serves in data buffering, serial-to-parallel conversion circuits, and as a fundamental building block in more complex digital systems like data loggers and communication interfaces.

When designing with the 74LV164PW, several application notes are critical for reliability:

Always use decoupling capacitors close to the VCC and GND pins to suppress power supply noise.

If the clock line is long or noisy, consider implementing signal conditioning to prevent false triggering.

Unused inputs (including the second data input) should never be left floating; they must be tied to VCC or GND as required by the logic function.

For applications driving capacitive loads, be mindful of the increased current surge during output transitions.

ICGOODFIND: The 74LV164PW is an excellent choice for designers seeking a reliable, low-voltage solution for serial-to-parallel conversion and I/O expansion. Its wide voltage range, compact package, and straightforward interface make it a versatile component in the digital designer's toolkit, effectively bridging the gap between limited microcontroller pins and the need for multiple parallel outputs.

Keywords: Serial-In/Parallel-Out, Shift Register, I/O Expansion, Low-Voltage CMOS, NXP 74LV164PW.