The 74LV165A is an 8-bit parallel-load or serial-in shift register with complementary serial outputs (Q7 and Q7) available from the last stage. When the parallel-load input (PL) is LOW, parallel data from the inputs D0 to D7 are loaded into the register asynchronously. When input PL is HIGH, data enters the register serially at the input DS. It shifts one place to the right (Q0?? → Q1 → Q2, etc.) with each positive-going clock transition. This feature allows parallel-to-serial converter expansion by tying the output Q7 to the input DS of the succeeding stage.

The clock input is a gate-OR structure which allows one input to be used as an active LOW clock enable input (CE) input. The pin assignment for the inputs CP and CE is arbitrary and can be reversed for layout convenience. The LOW-to-HIGH transition of the input CE should only take place while CP HIGH for predictable operation.

Schmitt-trigger action at all inputs, makes the circuit tolerant for slower input rise and fall times. It is fully specified for partial-power-down applications using I_OFF. The I_OFF circuitry disables the output, preventing the damaging current backflow through the device when it is powered down.