Master Slave Flipflop - mbits-mirafra/digitalDesignCourse GitHub Wiki

Master-Slave Flipflop

Race Around Condition

A race-around condition is a type of timing problem that can occur in a JK flip-flop when the inputs change too quickly, caused by the output when it oscillates rapidly between two states. This condition can occur when the J and K inputs of the flip-flop are both high, causing the output to toggle rapidly between 1 and 0. This may result in the flipflop being unstable or uncertain.

Why Master-Slave Flipflops?

Master-Slave flipflops are mainly used to avoid the timing problems associated with JK flip-flops, such as the possibility of race conditions that can occur when both inputs change simultaneously.

When the clock signal transitions from low to high, the master latch that latches the input data and sets its output, while the slave latch remains in its previous state. Then, when the clock signal transitions from high to low, the slave latch captures the output of the master latch, and its output updates to the same state as the master latch.

By using this master-slave arrangement, the flip-flop avoids race conditions and provides a more reliable and predictable behavior than simple latches or flip-flops.

Master-slave JK flipflop

A Master-Slave JK flip-flop is a type of digital circuit that is used for storing binary data. It consists of two JK latch connected together in a way that allows them to operate as a single unit called Master-Slave Flipflop. So, in a Master-Slave flip-flop, the slave is designed to obey or follow the master latch.

The "master" latch is controlled by an input signal called the "clock," and it sets or resets the output based on the state of the input signal. The "slave" latch is connected to the output of the master latch and also controlled by the clock signal. It captures and holds the value of the master's output when the clock signal transitions from one state to another.

Working

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  • When the clock pulse goes to 1, the slave is isolated; J and K inputs may affect the state of the system. The slave latch is isolated until the CP goes to 0. When the CP goes back to 0, information is passed from the master latch to the slave and output is obtained.

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  • When J = 0, K = 0 and clk is 1 master will be active and slave wont be active due to a inverter. Lets assume a value 0 to Q ad Q' will be 1 to both master and slave output hence there will be no change in the output and occurs in positive edge for master and when clock is 0 it occurs in negative edge for slave and it remains in the hold state.

  • When J = 0, K = 1 and clk is 1 master will be active and slave wont be active due to a inverter. Lets assume a value 0 to Q ad Q' will be 1 to both master and slave output hence output remains same as input and occurs in positive edge for master and when clock is 0 it occurs in negative edge for slave and it remains in the reset state.

  • When J = 1, K = 0 and clk is 1 master will be active and slave wont be active due to a inverter. Lets assume a value 0 to Q ad Q' will be 1 to both master and slave output hence output remains same as input and occurs in positive edge for master and when clock is 0 it occurs in negative edge for slave and it remains in the set state.

  • When J = K = 1, and clk is 1 master will be active and slave wont be active due to a inverter. Lets assume a value 0 to Q ad Q' will be 1 to both master and slave output hence output Q will be 1 and Q' is 0 and then at the positive edge of the clock pulse, the master flip flop toggles (means the change of the previous state into its opposite state), and at the negative edge of the clock pulse, the slave flip flop toggles.

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Applications of Master-Slave flipflops

1. Counters :

Counters are used in many electronic devices, including digital clocks, timers, and frequency dividers. In these devices, Master-Slave JK flip-flops are used to store and update the count value.

2. Memory Chips :

Memory chips are used to store binary data for a short period. RAM (Random Access Memory) chips use Master-Slave JK flip-flops to store and retrieve data.

3. Digital Signal Processors (DSPs):

DSPs are used to process digital signals in real-time. In these devices, Master-Slave JK flip-flops are used in the pipelining and sequencing of digital signal processing operations.

Advantages :

  1. Elimination of race conditions: The master-slave JK flip-flop eliminates race conditions that can occur in other types of flip-flops.

  2. Improved Noise Immunity : The Master latch captures the input signal and holds it for a short period of time before it is transferred to the Slave latch. During this time, any noise on the input signal is filtered out, and only a clean signal is transferred to the Slave latch.

Disadvantages :

  1. Complexity: The master-slave JK flip-flop requires more circuitry than other types of flip-flops, such as the D flip-flop. This complexity makes it more difficult to design and test.

  2. Power Consumption: The master-slave JK flip-flop requires more power to operate than other flip-flops. This can be an issue in battery-powered or low-power applications where power consumption is a concern.