Структура и элементная база цифровых систем. Реализуемая логическая функция. Нагрузочная способность, страница 11

F_Q - функция перехода :  0 - хранение предыдущего состояния ;

D - переключение в состояние "1";

Ñ - переключение в состояние "0"

Комбинация входов  R и S, равная  11, является запрещенной, так как в этом случае состояние триггера не определено.

RS - триггер, синхронизируемый уровнем

Условное обозначение и логическая схема

 

R  T                    Q                                R              Q

S                 УС                     БЯ

C                                                                                                                                _           

S                        _                                 CQ

Q

Временная диаграмма работы триггера и таблица состояний

U       

 C                                                                                        

С	R	S	Qn+1
0 1 1 1 1	x 0 0 1 1	x 0 1 0 1	Qn Qn  1 0 x

                                                                                           t  

 R        

                                                                                           t

  S        

                                                                                           t   

 Q

             t                        

  _

  Q                                                                                      t     

RS- триггер, синхронизируемый фронтом

Условное обозначение и логическая схема

                                                                                                                                   и

R  TT                                   R                              R₁                            Q₁                      R₂                   Q

                                           Q                                УС                               _                                             

                C                         _             C                               S₁       БЯ       Q₁                                                           БЯ                 _{__}        

                                           Q                                                                                     и       S₂                    Q    

SS

не          _

C

Временная диаграмма работы триггера, синхронизируемого фронтом

                       U   

 

                       C                                                                                   t

R                                                                                   t

 

                       S

                                                                                                             t

                      Q₁        

                      _                                                                                     t

                      Q₁

                                                                                                              t

                      R₂

                                                                                                              t

                      S₂

                                                                                                              t    

 

Q