74AUP1Z04 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 5 — 9 August 2012 17 of 28
NXP Semiconductors
74AUP1Z04
Low-power X-tal driver with enable and internal resistor
13. Application information
Crystal controlled oscillator circuits are widely used in clock pulse generators because of
their excellent frequency stability and wide operating frequency range. The use of the
74AUP1Z04 provides the additional advantages of low power dissipation, stable operation
over a wide range of frequency and temperature and a very small footprint. This
application information describes crystal characteristics, design and testing of crystal
oscillator circuits based on the 74AUP1Z04.
13.1 Crystal characteristics
Figure 12 is the equivalent circuit of a quartz crystal.
The reactive and resistive component of the impedance of the crystal alone and the
crystal with a series and a parallel capacitance is shown in Figure 13
.
f
i
= 1 kHz.
V
O
is constant.
T
amb
= 25 C.
Fig 10. Test set-up for measuring forward
transconductance
Fig 11. Typical forward transconductance as a
function of supply voltage
001aai360
0.47 μF 100 μF
V
CC
X
2
X
1
V
i
I
o
R
bias
V
CC
(V)
04312
001aad074
10
20
30
g
fs
(mA/V)
0
g
fs
I
O
V
I
---------
=
Fig 12. Equivalent circuit of a crystal
001aai361
C
X1
C
X0
L
X1
R
X1
=
