Digital Electronics NUMBER SYSTEM BINARY CODES BOOLEAN ALGEBRA K MAPS COMBINATIONAL CKT SEQUENTIAL CIRCUITS INTRODUCTION CLOCK BISTABLE MULTIVIBRATOR DERIVATION of FLIPFLOP circuit RS FLIPFLOP RS FLIPFLOP(NAND IMPLEMENTATION) R'S' FLIPFLOP Clocking RS LATCH Other LATCHes Timing problem in LATCHES ASYNCHRONUS INPUTS Parameters of CLOCK pulse QUESTIONS(LATCH using MUX) EDGE SENSITIVE LATCH (i.e. FLIPFLOP) MASTER SLAVE FF D FF USING MUX TIMING PARAMETERS OF FF CHARACTERISTIC EQUATIONS OF FFs EXCITATION TABLES OF FF CONVERSION OF 1 FF TO OTHER FF as 1bit MEMORY CELL REGISTERS SHIFT REGISTERS RING COUNTER JOHNSON COUNTER QUESTION(Serial Data transfer) ASYNCHRONOUS COUNTERS RIPPLE COUNTER COUNTER other than MOD-2n Designing COUNTER Using K-MAPS QUESTION(MOD 6 counter) QUESTION(Counter design) DOWN COUNTER QUESTION(Counter design) GLITCH SYNCHRONOUS COUNTER COMPARISON B/W SYNC. & ASYNC. COUNTERS CLOCK SKEW QUESTION(Maximum frequency question) QUESTION(Maximum frequency question) MORE QUESTIONS TIMING CIRCUITS

INTRODUCTION

In Sequential circuits output is a function of present inputs and pat output. These circuits have a feedback element or memory element which stores the output of the circuit and makes it available at the input. The following is the general diagram of sequential circuits:

The binary information stored in the memory element that is fed back into the circuit defines the state of the circuit. Sequential circuits are of two types:

Synchronous circuits: In these types of circuit, output is defined only on the basis of values of inputs at discrete instants of time. In these circuits we use flip-flops as memory devices and a common clock is used to control the working of the circuit. A clock is a periodic wave which continuously changes its state from 1 to 0 and 0 to 1 as

When-ever pulse goes from high to low, it is called FALLING or TRAILING EDGE and when pulse goes from low to high, it is called RISING EDGE.

Asynchronous circuits: In these types of circuit every change in the inputs affects output and output depends on values at every instant of the inputs. All the circuits which don’t have any flip-flops or clock are called Asynchronous circuits. Hence all the combinational circuits are Asynchronous circuits.