74LS166 DIP Parallel-Load 8-Bit Shift Register
The 74LS166 is a high speed TTL integrated circuit designed as an 8-bit shift register that can perform parallel-to-serial data conversion. Unlike the 74LS165, the 74LS166 features a synchronous load operation, meaning data is loaded from the eight parallel inputs into the register on the next positive-going transition of the clock pulse when the shift/load input is low. This ensures all data movements are perfectly timed with the system clock.
The IC consists of eight JK flip-flops with a common clock and a common clear input. The master reset is asynchronous, allowing for an immediate override to clear the register to zero at any time. A clock inhibit pin is also provided to give the user total control over the shifting process. Its architecture is ideal for high-speed digital systems requiring synchronized data capture and serial transmission, such as telemetry, communication interfaces, and microprocessor peripheral expansion.
KEY FEATURES
- 8-bit parallel-to-serial shift register
- Synchronous parallel load for precise timing
- Asynchronous master clear for immediate reset
- Clock inhibit input to pause shifting operations
- Fully compatible with most TTL and CMOS logic families
- Standard 16 pin dual in line package
SPECIFICATIONS
- Supply Voltage 4.75V to 5.25V
- Operating Temperature 0 to 70 Celsius
- Logic Type TTL Low Power Schottky
- Maximum Clock Frequency 25MHz
- Typical Propagation Delay 20ns
- High Level Output Current -0.4mA
- Low Level Output Current 8mA
INTERFACES
- SER Serial data input for cascading
- A to H Parallel data inputs
- SH/LD Shift or parallel load control input
- CLK Clock input positive edge triggered
- CLK INH Clock inhibit input
- CLR Clear input asynchronous active low
- QH Serial data output
- VCC Positive supply voltage
- GND Ground reference
