FS791/92/94
Document #: 38-07343 Rev *A
Page 7 of 9
Application Notes and Schematics
The schematics below demonstrate the use of the FS791/FS792/FS794 in a practical application.
The schematics on this page demonstrate how to use the
FS791, FS792 and FS794 in a practical application.
Note that the crystal circuit in Figure 6 and Figure 7 are de-
signed for a 3rd overtone crystal. This requires an inductor and
DC blocking capacitor referenced as LX and CX in the above
circuits.
Figure 8 at the right uses a 25-MHz crystal and assumes it is
not a 3rd overtone cut. If it is a 3rd overtone crystal, LX and CX
must be installed as in Figure 6 and Figure 7.
Refer to the crystal or ceramic resonator manufacturer’s spec-
ifications for the exact values of C4, C5 and LX. Cin (pin 1) and
Cout (pin 2) = 8 pF each, which must be included in calculating
the value of C4 and C5.
VDD
VDD
**
** Occasionally, C8 is used to create
a second pole for loop stability.
Mount loop filter components
close to pin 4.
R6
R1
10 ohm
R4
22 ohm
C2
0.1 uF., 16 V
C1
10 - 22 uF., 10 V, Tantalum
C8
C7
U1
FS791
Xin
1
Xout
2
S1
3
FSOUT
6
S0
7
C5
22 pF., 50 V
Y1
100 MHz
CX
0.033 uF.
LX
C4
22 pF., 50 V
VCC
FSOUT
Figure 6.
VDD
**
** Occasionally, C8 is used to create
a second pole for loop stability.
Mount loop filter components
close to pin 4.
R6
R1
10 ohm
R4
22 ohm
C2
0.1 uF., 16 V
C4
22 pF., 50 V
C5
22 pF., 50 V
Y1
50 MHz
C1
10 - 22 uF., 10 V, Tantalum
C8
C7
U1
FS792
Xin
1
Xout
2
S1
3
FSOUT
6
S0
7
LX
CX
0.033 uF.
VCC
FS
Figure 7.
VDD
**
** Occasionally, C8 is used to create
a second pole for loop stability.
Mount loop filter components
close to pin 4.
R6
R1
10 ohm
R4
22 ohm
C2
0.1 uF., 16 V
C4
22 pF., 50 V
C5
22 pF., 50 V
Y1
25 MHz
C1
10 - 22 uF., 10 V, Tantalum
C8
C7
U1
FS794
Xin
1
Xout
2
S1
3
FSOUT
6
S0
7
VCC
FSOUT
Figure 8.
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