Pertemuan:10 (Seq Circuit; Flip Flop, Latch)

11/02/2013 02:20:00 PM (Basic) Digital Technique 0 Comments

In this section, the discusion is about :

Sequencial Circuit; 
-Flip Flop
-Latch


Sequencial Circuit:
• Combinational Logic:
– Output depends only on current input
– Able to perform useful operations (add/subtract/multiply/encode/decode/select[mux]/etc…)
– Require cascading of many structures
– Costly and inflexible

• Sequential Logic:
– Output depends not only on current input but also on past input values
– Store information between operations
– Need some type of memory (Register) to remember the past input values.

Flip-Flop:
The flip-flops receive their inputs from the combinational circuit and also from a clock signal with edges (rising or falling) that occur at fixed intervals of time, as shown in the timing diagram.


Latch:
• Level triggered
• Latches are “transparent” (= any change on the inputs is seen at the outputs immediately).
• This causes synchronization problems! (not recommended for use in synchronous designs)
• Solution: use latches to create flip-flops that can respond (update) ONLY on SPECIFIC times (instead of ANY time).




You can download full chapter from this link:
BDT10-Flip Flop, Latch