LAN8710 Datasheet, PDF (65/79 Pages) SMSC Corporation – MII/RMII 10/100 Ethernet Transceiver with HP Auto-MDIX and flexPWR Technology in a Small Footprint

MII/RMII 10/100 Ethernet Transceiver with HP Auto-MDIX and flexPWR^® Technology in a Small Footprint
Datasheet
6.6
Clock Circuit
LAN8710/LAN8710i can accept either a 25MHz crystal or a 25MHz single-ended clock oscillator
(±50ppm) input. If the single-ended clock oscillator method is implemented, XTAL2 should be left
unconnected and XTAL1/CLKIN should be driven with a nominal 0-3.3V clock signal. See Table 6.12
for the recommended crystal specifications.
Table 6.12 LAN8710/LAN8710i Crystal Specifications
PARAMETER
Crystal Cut
Crystal Oscillation Mode
Crystal Calibration Mode
Frequency
Frequency Tolerance @ 25^oC
Frequency Stability Over Temp
Frequency Deviation Over Time
Total Allowable PPM Budget
Shunt Capacitance
Load Capacitance
Drive Level
Equivalent Series Resistance
Operating Temperature Range
LAN8710/LAN8710i
XTAL1/CLKIN Pin Capacitance
LAN8710/LAN8710i XTAL2 Pin
Capacitance
SYMBOL
F_fund
F_tol
F_temp
F_age
C_O
C_L
P_W
R₁
MIN
NOM
MAX
AT, typ
Fundamental Mode
Parallel Resonant Mode
-
25.000
-
-
-
±50
-
-
±50
-
+/-3 to 5
-
-
-
±50
-
7 typ
-
-
20 typ
-
300
-
-
-
-
30
Note 6.4
-
Note 6.5
-
3 typ
-
-
3 typ
-
UNITS
MHz
PPM
PPM
PPM
PPM
pF
pF
uW
Ohm
o_C
pF
pF
NOTES
Note 6.1
Note 6.1
Note 6.2
Note 6.3
Note 6.6
Note 6.6
Note 6.1
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 6.2 Frequency Deviation Over Time is also referred to as Aging.
Note 6.3
Note 6.4
Note 6.5
The total deviation for the Transmitter Clock Frequency is specified by IEEE 802.3u as
±100 PPM.
0^oC for extended commercial version, -40^oC for industrial version.
+85^oC for extended commercial version, +85^oC for industrial version.
Note 6.6
This number includes the pad, the bond wire and the lead frame. PCB capacitance is not
included in this value. The XTAL1/CLKIN pin, XTAL2 pin and PCB capacitance values are
required to accurately calculate the value of the two external load capacitors. The total load
capacitance must be equivalent to what the crystal expects to see in the circuit so that the
crystal oscillator will operate at 25.000 MHz.
SMSC LAN8710/LAN8710i
65
DATASHEET
Revision 1.0 (04-15-09)