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When both the inputs of a latch are high, the output is unpredictable. What is this condition called?
The truth table for SR latch is:
From the above table, when both the inputs of a latch are high, The out is indeterminate.
Which property is NOT considered in latches?
(i) Latches are level-triggered (outputs can change as soon as the inputs changes)
(ii) Flip-Flop is edge-triggered (only changes state when a control signal goes from high to low or low to high).
(iii) Edge triggering is a type of triggering that allows a circuit to become active at the positive edge or the negative edge of the clock signal.
(iv) Level triggering is a type of triggering that allows a circuit to become active when the clock pulse is on a particular level.
Which of the following can be used for debouncing a switch ?
______ is commonly used to interface output devices.
Latches are memory devices and can store one bit of data for as long as the device is powered.
As the name suggests, latches are used to "latch onto" information and hold it in place.
Latches are very similar to flip-flops, but are not synchronous devices, and do not operate on clock edges as flip-flops do.
The reason for using the latch in an output port is simple, we do not want to lose the result of any operation.
So, in order to not lose it, we use a latch, so that it holds the information as long as new information is overwritten onto it.
An 8-bit latch can be used to interface the output of a microprocessor to other devices.
The 74LS373 octal latch and the 74LS374 octal D flip-flop are popular microprocessor interface chips.
Tristate buffer is commonly used to interface input devices.
The two inputs A and B are connected to a NOR based R-S latch, via two AND gates as shown in the figure. If A = 1 and B = 0, the output QQ̅ is
From the given diagram,
S = AQ̅, R = QB
Given that, A = 1, B = 0
S = Q̅, R = 0
The truth table of the S-R latch is:
Let Q = 0,
S = Q̅ = 1, R = 0 ⇒ Qn + 1 = 1
Let Q = 1,
S = Q̅ = 0, R = 0 ⇒ Qn + 1 = 1
In both the cases, Qn + 1 Q̅n + 1 = 10
In the latch circuit shown, the NAND gates have non-zero, but unequal propagation delays. The present input conditions is: P = Q = ‘0’. If the input conditions is changed simultaneously to P = Q = ‘1’, the outputs X and Y are
Let as assume tpd 1 < tpd 2
x changes state first then y changes
1st output of X (P = 1, y = 0) ⇒ X1 = 1
Next output of Y (Q = 1, X1 = 1) ⇒ Y1 = 0
2nd output of X (P = 1, y1 = 0) ⇒ 1
Hence output x = 1 y = 0 (if tpd1 < tpd2)
& Output X = 0 Y = 1 (if tpd2 < tpd1)
An SR latch is implemented using TTL gates as shown in the figure. The set and reset pulse inputs are provided using the push-button switches. It is observed that the circuit fails to work as desired. The SR latch can be made functional by changing
Hence for the above circuit to work as an SR latch, 5-volt battery should connect to ground.
Hence option -4 is Correct.
Which of the following is true?
The difference between latches and flip flops is shown
In S-R latch, when the SET input is made high, output Q becomes:
An unclocked R-S flip flop using NOR gates is as shown:
The truth table for the circuit is shown:
The first step of the analysis procedure of SR latch is to ___________
All flip flops have at least one output labeled Q (i.e. inverted). This is so because the flip flops have inverting gates inside them, hence in order to have both Q and Q complement available, we have atleast one output labelled.
When both inputs of SR latches are high, the latch goes ___________
When both gates are identical and this is “metastable”, and the device will be in an undefined state for an indefinite period.
When a high is applied to the Set line of an SR latch, then ___________
S input of an SR latch is directly connected to the output Q. So when a high is applied Q output goes high and Q’ low.
The full form of SR is ___________
The full form of SR is set/reset. It is a type of latch having two stable states.
The outputs of SR latch are ___________
SR or Set-Reset latch is the simplest type of bistable multivibrator having two stable states. The inputs of SR latch are s and r while outputs are q and q’. It is clear from the diagram:
When both inputs of SR latches are low, the latch ___________
When both inputs of SR latches are low, the latch remains in it’s present state. There is no change in output.