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LAN9730 Datasheet, PDF (211/222 Pages) SMSC Corporation – High-Speed Inter-Chip (HSIC) USB 2.0
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LAN9730/LAN9730i
7.6.2 100 µW 25 MHZ CRYSTAL SPECIFICATIONS
When utilizing a 100 µW 25 MHz crystal, the following circuit design (Figure 7-12) and specifications (Table 7-24) are
required to ensure proper operation.
FIGURE 7-12:
100 µW 25 MHZ CRYSTAL CIRCUIT
LAN9730
XO
RS
Y1
XI
C1
C2
TABLE 7-24: 100 µW CRYSTAL SPECIFICATIONS
Parameter
Crystal Cut
Crystal Oscillation Mode
Crystal Calibration Mode
Frequency
Frequency Tolerance @ 25oC
Frequency Stability Over Temp
Frequency Deviation Over Time
Total Allowable PPM Budget
Shunt Capacitance
Load Capacitance
Drive Level
Equivalent Series Resistance
XO Series Resistor
Operating Temperature Range
XI Pin Capacitance
XO Pin Capacitance
Symbol
Min.
AT, typ
Fundamental Mode
Parallel Resonant Mode
Ffund
-
Ftol
-
Ftemp
-
Fage
-
-
CO
-
CL
8
PW
-
R1
-
RS
495
Note 7-18
-
-
Nom.
25.000
-
-
+/-3 to 5
-
-
-
100
-
500
-
3 typ
3 typ
Max.
Unit
Note
-
+/-50
+/-50
-
+/-50
5
12
80
505
Note 7-19
-
-
MHz
PPM
PPM
PPM
PPM
pF
pF
µW
Ohm
Ohm
oC
pF
pF
Note 7-15
Note 7-15
Note 7-16
Note 7-17
Note 7-20
Note 7-20
Note 7-15
Note 7-16
Note 7-17
Note 7-18
Note 7-19
Note 7-20
The maximum allowable values for frequency tolerance and frequency stability are application
dependent. Since any particular application must meet the IEEE +/-50 PPM Total PPM Budget, the
combination of these two values must be approximately +/-45 PPM (allowing for aging).
Frequency Deviation Over Time is also referred to as Aging.
The total deviation for the Transmitter Clock Frequency is specified by IEEE 802.3u as +/-50 PPM.
0oC for commercial version, -40oC for industrial version.
+70oC for commercial version, +85oC for industrial version.
This number includes the pad, the bond wire and the lead frame. PCB capacitance is not included in
this value. The XO/XI pin and PCB capacitance values are required to accurately calculate the value
of the two external load capacitors. These two external load capacitors determine the accuracy of the
25.000 MHz frequency.
 2012-2015 Microchip Technology Inc.
DS00001946A-page 211
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