Using The Hmos On-Chip Oscillator; Esr Vs Frequency - Intel MCS 51 User Manual

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HARDWARE DESCRIPTION OF THE 8051,8052 AND80C51
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xrALl
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270252-23
Figure29.On-Chip Osciiiator Circuitry in
the HMOS Versions of the MCS@-51Famiiy
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--------
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xrALl ----
xraLr -----
ouAnr2cRvalAL
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ORC6RANICRESOWIOR
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270252-24
Figure 30. Using the HMOS On-Chip Oeciiiator
The
crvstal meeifkationa and cauacitanee values (Cl
and C2-inFi&re 30)are not criti&l. 30 pF can be u&i
irr these positionsat any frequencywith good quality
crystals. A ceramic resonator can be used in place of
the crystal in cost-sensitiveapplications. When a ce-
ramic resonatoris used,Cl and C2arenormally s eleet-
edto beof somewhat higher v aluea, typically, 47 pF.
The manufacturer of the ceramic resonator should be
consulted for recmnmcndationson the
vaiucs
of thCSC
capacitors.
In general, crystals used with these devices typically
have the followingspecifications:
ESR (EquivalentSeriesResistance) seeFigure 31
c20(ShuntCapacitance)
7.opFmax.
CL(bid ~pr$ei~ee) 30pF *3 pF
Drive Level 1 mW
4
a
12 16
CRYS7AL FSEQUEHCV i n MHz
270252-34
—. - -—— -
Figure 31. ESR VSFr6!qUenOy
3-31