Datasheet

www.ti.com
APPLICATION INFORMATION
NC
R
s
≅ 1 kΩ
C
L
= 16 pF
C
2
≅ 32 pF
GND
X1
C
LOAD
R
LOAD
R
F
≅ 2.2 MΩ
C
1
≅ 32 pF
1
2
3 4
5
6
Y
b) Oscillator Circuit in DBV or DCK Pinout
V
CC
X2
Practical Design Tips
SN74LVC1GX04
CRYSTAL OSCILLATOR DRIVER
SCES581B – JULY 2004 – REVISED DECEMBER 2006
Figure 3. Oscillator Circuit (continued)
• The open-loop gain of the unbuffered inverter decreases as power-supply voltage decreases. This decreases
the closed-loop gain of the oscillator circuit. The value of R
s
can be decreased to increase the closed-loop
gain, while maintaining the power dissipation of the crystal within the maximum limit.
• R
s
and C
2
form a low-pass filter and reduce spurious oscillations. Component values can be adjusted, based
on the desired cutoff frequency.
• C
2
can be increased over C
1
to increase the phase shift and help in start-up of the oscillator. Increasing C
2
may affect the duty cycle of the output voltage.
• At high frequency, phase shift due to R
s
becomes significant. In this case, R
s
can be replaced by a capacitor
to reduce the phase shift.
8
Submit Documentation Feedback