TEMPERATURE CHARACTERISTICS

Figure 9 and Figure 10 give temperature variations in drain

characteristics for the N-channel and P-channel devices op-

erating at V

seen from these curves the output sink and source current

decreases as temperature increases. The effect is almost

linear and can be closely approximated by a temperature co-

efficient of −0.3% per degree centigrade.

Since the t

the temperature dependence of t

at which the output load capacitance can be charged and

discharged. This in turn is a function of the sink/source cur-

rent which was shown above to vary as −0.3% per degree

centigrade. Consequently we can say that t

−0.3% per degree centigrade. Actual measurements of t

pd

with temperature verifies this number.

The drain characteristics of

Figure 9 and Figure 10 show

considerable variation with temperature. Examination of the

transfer characteristics of

Figure 11 indicates that they are

almost independent of temperature. The transfer character-

istic is not dependent on temperature because although both

the N-channel and P-channel device characteristics change

with temperature these changes track each other closely.

The proof of this tracking is the temperature independence

of the transfer characteristics. Noise margin and maximum/

minimum logic levels will then not be dependent on tempera-

ture.

As discussed previously power consumption is a function of

C

tially constant with temperature except I

the leakage current specified on each 54C/74C device ap-

plies across the entire temperature range and therefore rep-

resents a worst case limit.

AN006021-12

(A) Typical Output Drain Characteristic (N-Channel)

AN006021-13

(B) Typical Output Drain Characteristic (P-Channel)

FIGURE 9.

AN006021-14

(A) Typical Output Drain Characteristic (N-Channel)

AN006021-15

(B) Typical Output Drain Characteristic (P-Channel)

FIGURE 10.

AN006021-16

FIGURE 11. Typical Gate Transfer Characteristics

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