1.2 KiB
1.2 KiB
- Output depends on input and past behavior
- Requires use of storage elements
Latches
SR Latch
SR stands for Set/Reset, and functions like so:
- When a signal comes into
S,Q_ais set on and stays on until a signal comes intoR, at which point the output (Q_a) is reset, back to zero. SandRare interchangeable, it just impacts whetherQ_aorQ_bis set/reset. Truth table:
S |
R |
Q_a |
Q_b |
|---|---|---|---|
| 0 | 0 | 0/1 | 1/0 |
| 0 | 1 | 0 | 1 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 0 |
! |
Gated Latch
A gated latch is similar to a basic latch, but the output only changes when clk = 1.
D Latch
A D latch has two inputs, clk and data. When clk is high, data is stored.
Flip Flops
A latch, but the output only changes on one of the clock edges
- Can be a rising edge latch or a falling edge latch
JK Flip Flop
Similar to an SR flip flop, a JK flip flop has set/reset inputs, but when both inputs are high, then the output is toggled.
T Flip Flop
A T Flip Flip, or a toggle flip flop has two inputs:
clk- Clock inputT- WheneverTgoes from low to high, the output toggles its state