SN74ALS166

SN74ALS166 PARALLEL-LOAD 8-BIT SHIFT REGISTER SDAS156D – APRIL 1982 – REVISED AUGUST 2000 D Synchronous Load D Direct Overriding Clear D Parallel-to-Serial Conversion D Package Options Include Plastic Small-Outline (D) and Shrink Small-Outline (DB) Packages and Standard Plastic (N) DIP description The SN74ALS166 parallel-load 8-bit shift register is compatible with most other TTL logic families. All inputs are buffered to lower the drive requirements. Input clamping diodes minimize switching transients and simplify system design. D, DB, OR N PACKAGE (TOP VIEW) SER 1 A2 B3 C4 D5 CLK INH 6 CLK 7 GND 8 16 VCC 15 SH/LD 14 H 13 QH 12 G 11 F 10 E 9 CLR These parallel-in or serial-in, serial-out registers have a complexity of 77 equivalent gates on the chip. They feature gated clocks (CLK and CLK INH) inputs and an overriding clear (CLR) input. The parallel-in or serial-in modes are established by the shift/load (SH/LD) input. When high, SH/LD enables the serial data (SER) input and couples the eight flip-flops for serial shifting with each clock pulse. When low, the parallel (broadside) data (A–H) inputs are enabled and synchronous loading occurs on the next clock pulse. During parallel loading, serial data flow is inhibited. Clocking is accomplished on the low-to-high-level edge of the clock pulse through a two-input positive-NOR gate, permitting one input to be used as a clock-enable or clock-inhibit function. Holding either of the clock inputs high inhibits clocking; holdi...