Datasheet

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APPLICATION INFORMATION
Values of C
1
and C
2
are chosen so that
C
L
+
C
1
C
2
C
1
) C
2
and C
1
≡ C
2
. R
s
is the current-limiting resistor, and the
of C
2
at resonance frequency, i.e.,
R
s
+ X
C
2
. R
F
is the feedback resistor that is used to bias the inverter in the
R
F
≅ 2.2 MΩ
C
L
≅ 16 pF
C
1
≅ 32 pF C
2
≅ 32 pF
X2
X1
C
LOAD
R
LOAD
a) Logic Diagram View
R
s
≅ 1 kΩ
Y
SN74LVC1GU04
Portion
SN74LVC1G04
Portion
SN74LVC1GX04
CRYSTAL OSCILLATOR DRIVER
SCES581B – JULY 2004 – REVISED DECEMBER 2006
Figure 3 shows a typical application of the SN74LVC1GX04 in a Pierce oscillator circuit. The buffered inverter
(SN74LVC1G04 portion) produces a rail-to-rail voltage waveform. The recommended load for the crystal shown
in this example is 16 pF. The value of the recommended load (C
L
) can be found in the crystal manufacturer's
data sheet.
value depends on the maximum power dissipation of the crystal. Generally, the recommended value of R
s
is
specified in the crystal manufacturer's data sheet and, usually, this value is approximately equal to the reactance
linear region of operation. Usually, the value is chosen to be within 1 M Ω to 10 M Ω .
Figure 3. Oscillator Circuit
7
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