lan9512 Standard Microsystems Corp., lan9512 Datasheet - Page 44

• Manufacturer Part Number: lan9512
• Description: Usb Hub With Integrated 10/100 Ethernet Controller
• Manufacturer: Standard Microsystems Corp.

Revision 1.0 (04-20-09)
4.6
Crystal Cut
Crystal Oscillation Mode
Crystal Calibration Mode
Frequency
Frequency Tolerance @ 25
Frequency Stability Over Temp
Frequency Deviation Over Time
Total Allowable PPM Budget
Shunt Capacitance
Load Capacitance
Drive Level
Equivalent Series Resistance
Operating Temperature Range
LAN9512 XI Pin Capacitance
LAN9512 XO Pin Capacitance
PARAMETER
LAN9512 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
Note 4.12 The maximum allowable values for Frequency Tolerance and Frequency Stability are
Note 4.13 Frequency Deviation Over Time is also referred to as Aging.
Note 4.14 The total deviation for the Transmitter Clock Frequency is specified by IEEE 802.3u as
Note 4.15 This number includes the pad, the bond wire and the lead frame. PCB capacitance is not
Clock Circuit
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).
+/- 50 PPM.
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.
o
C
Table 4.6 LAN9512 Crystal Specifications
SYMBOL
F
F
F
F
P
C
temp
C
R
fund
age
tol
W
O
L
1
Table 4.6
DATASHEET
MIN
300
0
Parallel Resonant Mode
-
-
-
-
-
-
-
-
-
-
44
for the recommended crystal specifications.
Fundamental Mode
AT, typ
+/-3 to 5
25.000
20 typ
NOM
7 typ
3 typ
3 typ
-
-
-
-
-
-
USB Hub with Integrated 10/100 Ethernet Controller
+/-50
+/-50
+/-50
MAX
+70
50
-
-
-
-
-
-
-
UNITS
PPM
PPM
PPM
PPM
Ohm
MHz
uW
pF
pF
o
pF
pF
C
SMSC LAN9512
Note 4.12
Note 4.12
Note 4.13
Note 4.14
Note 4.15
Note 4.15
NOTES
Datasheet