UCD4021B

DESCRIPTION 

The UCD4021B is a 8-stage synchronous parallel or serial 

input/serial output registers having common CLOCK and 

PARALLEL/SERIAL CONTROL inputs, a SERIAL data input, and 

individual parallel inputs to each register stage. Each register is a 

D-type, master-slave flip-flop. Q6, Q7, and Q8 are outputs. In 

UCD4021B serial entry is synchronous with the clock but parallel 

entry is asynchronous. 

In UCD4021B serial entry is controlled by the PARALLEL/SERIAL 

CONTROL input. When the PARALLEL/SERIAL CONTROL input is 

low, data is serially shifted into the 8-stage register synchronously with 

the positive transition of the clock line. When the PARALLEL/SERIAL 

CONTROL input is high, asynchronous parallel entry is made and the

CLOCK input of the internal stage is isolated. 

FEATURES 

* Up to 20V operation voltage 

* 12MHz (Typ.) clock rate at 10V 

* Maximum input current of 1μA at 18V 

* Fully static operation 

* 8 master-slave flip-flops plus output buffering and control gating 

 APPLICATIONS 

* General-purpose register 

* Parallel input/serial output data queueing 

* Parallel to serial data conversion