Datasheet

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APPLICATION INFORMATION
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 value
resonance frequency, i.e.,
R
s
+ X
C
2
. R
F
is the feedback resistor that is used to bias the inverter in the linear
CTRL
(1)
R
F
≅ 2.2 MΩ
C
L
≅ 16 pF
C
1
≅ 32 pF C
2
≅ 32 pF
XOUT
XIN
OSCOUT
Y
A
Optional Signal-Conditioning Stage
C
LOAD
R
LOAD
C
LOAD
R
LOAD
(1) CTRL should be tied to logic high during normal operation of the oscillator circuit. To disable the oscillator circuit, connect CTRL to logic low.
A) Logic Diagram View
R
s
≅ 1 kΩ
SN74LVC1404
OSCILLATOR DRIVER
FOR CRYSTAL OSCILLATOR OR CERAMIC RESONATOR
SCES469D – AUGUST 2003 – REVISED JANUARY 2007
Figure 3 shows a typical application of the SN74LVC1404 in a Pierce oscillator circuit. The output voltage can
be conditioned further by connecting OSCOUT to the Schmitt-trigger input inverter. The Schmitt-trigger input
inverter 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. Values
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 of C
2
at
region of operation. Usually, the value is chosen to be within 1 M Ω to 10 M Ω .
Figure 3. Oscillator Circuit
8
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