NXP 74HCT4094D,118: An 8-Bit Serial-In/Serial-or-Parallel-Out Shift Register with Output Latches

The NXP 74HCT4094D,118 is a high-speed CMOS logic 8-bit shift register designed for serial-to-parallel data conversion applications, featuring output latches for enhanced control and stability. This integrated circuit is part of the 74HCT family, which combines the low power consumption of CMOS technology with the operational ease and compatibility of TTL logic levels.

A primary function of this device is to efficiently convert a stream of serial data into parallel output. Data is input serially through the DS (Serial Data Input) pin and shifted through the internal registers on each low-to-high transition of the SHCP (Shift Register Clock Input). This allows for a simple, few-wire interface to a microcontroller, making it ideal for expanding output capabilities and controlling multiple devices like LEDs, relays, or displays.

A key distinguishing feature of the 74HCT4094 is its built-in output storage latches. The shifted data is transferred from the shift register stages to the output buffer latches upon a high-level signal applied to the STCP (Storage Register Clock Input or Latch Enable). This allows the system to shift in new data while the current outputs remain stable and unchanged, effectively eliminating flickering or glitches in display applications during data updates.

Furthermore, the IC provides both a standard parallel output and a serial output (Q7S) from the eighth bit. This serial output enables easy cascading of multiple devices, allowing for virtually unlimited output expansion with only three control lines from a host controller (Data, SHCP, STCP). An additional Output Enable (OE) pin provides tri-state control over the parallel outputs, allowing them to be placed in a high-impedance state when necessary.

The device operates over a broad voltage range (4.5V to 5.5V) and is characterized for operation from -40°C to +125°C. Its HCT technology ensures it can be directly interfaced with TTL microprocessors while maintaining the low power consumption and high noise immunity inherent to CMOS designs.

ICGOOODFIND: The 74HCT4094D,118 is an exceptionally versatile and robust solution for output expansion, serial-to-parallel data conversion, and applications requiring stable, latched outputs. Its ability to be cascaded and its simple 3-wire control interface make it a fundamental component for efficiently driving numerous outputs from a limited number of microcontroller pins.

Keywords: Shift Register, Serial-to-Parallel Converter, Output Latches, Output Expansion, Cascadable.