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LAN9303MI-AKZE Datasheet, PDF (382/386 Pages) SMSC Corporation – Small Form Factor Three Port 10/100 Managed Ethernet Switch with Dual MII/RMII/Turbo MII
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Small Form Factor Three Port 10/100 Managed Ethernet Switch with Dual MII/RMII/Turbo MII
Datasheet
14.6
Clock Circuit
The device can accept either a 25MHz crystal (preferred) or a 25MHz single-ended clock oscillator (+/-
50ppm) input. If the single-ended clock oscillator method is implemented, XO should be left
unconnected and XI should be driven with a nominal 0-3.3V clock signal. The input clock duty cycle
is 40% minimum, 50% typical and 60% maximum.
It is recommended that a crystal utilizing matching parallel load capacitors be used for the crystal
input/output signals (XI/XO). See Table 14.20 for 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
Operating Temperature Range
XI Pin Capacitance
XO Pin Capacitance
Table 14.20 Crystal Specifications
SYMBOL
Ffund
Ftol
Ftemp
Fage
CO
CL
PW
R1
MIN
NOM
MAX
UNITS NOTES
AT, typ
Fundamental Mode
Parallel Resonant Mode
-
25.000
-
-
-
+/-50
MHz
PPM
Note 14.22
-
-
-
-
-
300
-
Note 14.25
-
-
-
+/-3 to 5
-
7 typ
20 typ
-
-
-
3 typ
3 typ
+/-50
-
+/-50
-
-
-
30
Note 14.26
-
-
PPM
PPM
PPM
pF
pF
uW
Ohm
oC
pF
pF
Note 14.22
Note 14.23
Note 14.24
Note 14.27
Note 14.27
Note 14.22 The maximum allowable values for Frequency Tolerance and Frequency Stability are
application dependant. 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).
Note 14.23 Frequency Deviation Over Time is also referred to as Aging.
Note 14.24 The total deviation for the Transmitter Clock Frequency is specified by IEEE 802.3 as
+/- 50 PPM.
Note 14.25 0oC for commercial version, -40oC for industrial version.
Note 14.26 +70oC for commercial version, +85oC for industrial version.
Note 14.27 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.
Revision 1.5 (07-08-11)
382
DATASHEET
SMSC LAN9303M/LAN9303Mi
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