Combinational logic circuits Chapter 3 Combinational logic hazards
Combinational logic circuits Chapter 3 Combinational logic hazards
Circuits parameters a Vcc, power supply voltage 口Icc, power supply current cch CcL OL,VoH,士oL,oH d VIl, VIH, fIL, fIH 日tPLH,tpHL a Fan-out
Circuits Parameters Vcc, power supply voltage Icc, power supply current ◼ ICCH, ICCL VOL, VOH , IOL, IOH VIL, VIH, IIL, IIH tPLH, tPHL Fan-out
Hazard a boolean algebra does not account for propagation delays through signal paths of actually circuits The delay can cause glitches to occur. a glitch is an unwanted signal, usually a short pulse caused by the transient behavior of signal path that have different delays a a hazard exists any time the potential for itches is present a Glitches may not be a problem or they may create havoc. It depends on the specif ic application
Boolean algebra does not account for propagation delays through signal paths of actually circuits. The delay can cause glitches to occur. A glitch is an unwanted signal, usually a short pulse caused by the transient behavior of signal path that have different delays A hazard exists any time the potential for glitches is present. Glitches may not be a problem or they may create havoc. It depends on the specific application. Hazard
Static hazard D a static-1 hazard exists when an output variable should be a logic 1, but goes to o momentarily as a result of input variable changing a A static-o hazard exists when an output variable should be a logic 0, but goes to 1 momentarily as a result of input variable changing
Static hazard A static-1 hazard exists when an output variable should be a logic 1, but goes to 0 momentarily as a result of input variable changing. A static-0 hazard exists when an output variable should be a logic 0, but goes to 1 momentarily as a result of input variable changing
Static hazard 口P=Xy"+yZ ■=1.z=1 G4 y+y- Xy a Assuming all the G2 G3 gate have the same delay time
Static hazard P=XY’+YZ ◼ x=1, z=1 ◼ P=y’+y=1 ◼ Assuming all the gate have the same delay time, t Z P X Y XY’ ZY G1 G2 G3 G4 Y’