The 74VHC165FT is an advanced high speed CMOS 8-BIT PARALLEL/SERIAL-IN, SERIAL-OUT SHIFT REGISTER fabricated with silicon gate C2MOS technology. It achieves the high speed operation similar to equivalent Bipolar Schottky TTL while maintaining the CMOS low power dissipation. It consists of parallel-in or serial-in, serial-out 8-bit shift register with a gated clock input. When the SHIFT/LOAD input is held high, the serial data input is enabled and the eight frip-frops perform serial shifting with each clock pulse. When the SHIFT/LOAD input is held low, the parallel data is loaded synchronously into the register at positive going transition of the clock pulse. The CK-INH input should be shifted high only when the CK input is held high. An Input protection circuit ensures that 0 to 5.5 V can be applied to the input pins without regard to the supply voltage. This device can be used to interface 5 V to 3 V systems and on two supply systems such as battery backup. This circuit prevents device destruction due to mismatched supply and input voltages

Wide operating temperature range: Topr = -40 to 125 
High speed: fMAX = 150 MHz (typ.) at VCC = 5 V
Low power dissipation: ICC = 4.0 μA (max) at Ta = 25 
High noise immunity: VNIH = VNIL = 28 % VCC (min)
Power-down protection is provided on all inputs.
Balanced propagation delays: tPLH ≈ tPHL
Wide operating voltage range: VCC(opr) = 2.0 V to 5.5 V
Pin and function compatible with 74 series (74AC/HC/AHC etc.) 165 type