As in the case of discrete transistors, manufacturers do not agree on power supply labeling for
ICs. Some manufacturers use V+ to indicate the positive voltage and V- to indicate the negative
voltage, whereas another manufacturer might use the symbols VEE and VCC to represent negative
and positive respectively. Thus, the IC data sheet must be studied carefully before connecting
any power source. Typically, digital IC power supplies must be kept within + 5 to + 10 percent,
whereas linear ICs will generally operate satisfactorily with power sources of + 20 percent.
Power supply ripple and regulation are also important. Solid state power supplies with filtering
and voltage regulation are recommended. Ripple and any other power supply noise must be kept
below 1 percent for noise sensitive circuits. Proper sequencing of supply voltages should be
observed; refer to the manufacturers specifications.
Proper value capacitors are used with power supply circuits to provide decoupling of the power
supply (signal bypass). Usually, disc ceramic capacitors are used for this purpose. The
capacitors should always be connected as close to the IC terminals as is practical, not at the
power supply terminals. For linear IC power supply decoupling capacitors use capacitance
values between .1μF and .001μF.
Replaced/Superseded by document(s)
Many equipment item failures are precipitated by stress. When applied stress exceeds the
inherent strength of the part, either a serious parametric degradation or a failure will occur. To
assure reliability, equipment must be designed to endure stress over time without failure.
Parameters which stress a design must be identified and controlled. Parts and materials must be
selected which can withstand these stresses. Derating is the selection and application of parts
and materials so that applied stress is less than rated for a specific application. The derating
criteria in this manual have been developed to provide designers the greatest flexibility possible
in applying parts and materials compatible with the need for readiness.