Rs flipflop or SR flipFLop You can watch my lectures at: Digital electronics playlist in my youtube channel: https://www.youtube.com/channel/UC_fItK7wBO6zdWHVPIYV8dQ?view_as=subscriber My Website : https://easyninspire.blogspot.com/

1. RS Flip-
Flops

2. Today's Topic
Sequential Logic Circuits
• RS Flip-Flop

3. RS (or) SR Flip-Flop
• The S-R flip-flop is basic flip-flop among all the flip-flops.
• All the other flip flops are developed after SR-flip-flop.
• SR flip-flop operates with only positive clock transitions (or) negative
clock transitions.
• Whereas, SR latch operates with enable signal.

4. • The circuit diagram of SR flip-flop is shown in the following figure.
• This circuit has two inputs S & R and two outputs Q(t)& Q(t)’. The
operation of SR flip flop is similar to SR Latch.
• Consider, this flip-flop affects the outputs only when positive
transition of the clock signal is applied instead of active enable.
SR Latch

5. Clk S R Q Q’
+ve 0 0 NC NC
+ve 0 1 0 1
+ve 1 0 1 0
+ve 1 1 - -
-ve X X
SR Flip-Flop Truth Table

6. SR Flip-Flop Truth Table
CLK S R Q Q’ State
+ve 0 0 Q Q’ No Change
+ve 0 1 0 1 RESET
+ve 1 0 1 0 SET
+ve 1 1 1 or 0 0 or 1 Invalid
-ve X X Q Q’ No Change

7. S R Q(t) Q(t+1) State
0 0 0 0 No Change
0 0 1 1 No Change
0 1 0 0 RESET
0 1 1 0 RESET
1 0 1 1 SET
1 0 0 1 SET
1 1 1 - Invalid
1 1 0 - Invalid
Characteristic Table of S-R Flip-Flop

8. In Next Class
• D Flip Flop

9. • A