A logic-circuit family thaE used to be very popular is transistor-transistor logic (TTL). The TTL logic gates and other building blocks are available commercially in small-scale-integrated (SSI) and medium-scale-integrated (MSI) packages. Such packages can be assembled on printed-circuit boards to implement a digital system. The device data sheets provide the following specifications of the basic TTL inverter (of the SN7400 type): Logic-1 input level required to ensure a logic-0 level at the output: MIN (minimum) 2 V Logic-0 input level required to ensure a logic-1 level at the output: MAX (maximum) 0.8 V Logic-1 output voltage: MIN 2.4 V, TYP (typical) 3.3 V Logic-0 output voltage: TYP .22 V, MAX 0.4 V Logic-0-level supply current: TYP 3 mA, MAX 5 Ma Logic-1-level supply current: TYP 1 mA, MAX 2 mA
(a) Find the worst-case values of the noise margins.
(b) Assuming that the inverter is in the logic-1 state 50% of the time and in the logic-0 state 50% of the time, find the average power dissipation in a typical circuit. The power supply is 5 V.