LAN8740A Datasheet, PDF (125/136 Pages) Microchip Technology – Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology

LAN8740A/LAN8740Ai
3: The total deviation for the Transmitter Clock Frequency is specified by IEEE 802.3u as
±50 ppm.
4: 0°C for commercial version, -40°C for industrial version
5: +70°C for commercial version, +85°C for industrial version
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. These two external load capacitors determine the accuracy of
the 25.000 MHz frequency.
5.7.2 100 µW 25 MHZ CRYSTAL SPECIFICATIONS
When utilizing a 100 µW 25 MHz crystal, the following circuit design (Figure 5-9) and specifications (Table 5-16) are
required to ensure proper operation.
FIGURE 5-9:
100 µW 25 MHZ CRYSTAL CIRCUIT
LAN8740
XTAL2
R_S
Y1
XTAL1
C₁
C₂
TABLE 5-16: 100 µW CRYSTAL SPECIFICATIONS
Parameter
Crystal Cut
Crystal Oscillation Mode
Crystal Calibration Mode
Frequency
Frequency Tolerance at 25^oC
Frequency Stability Over Temp
Frequency Deviation Over Time
Total Allowable PPM Budget
Shunt Capacitance
Load Capacitance
Drive Level
Equivalent Series Resistance
XTAL2 Series Resistor
Operating Temperature Range
XTAL1/CLKIN Pin Capacitance
XTAL2 Pin Capacitance
Symbol
Min.
Nom.
AT, typ
Fundamental Mode
Parallel Resonant Mode
F_fund
-
F_tol
-
F_temp
-
F_age
-
-
C_O
-
C_L
8
P_W
-
R₁
-
R_S
495
(see Note 5)
-
-
25.000
-
-
±3 to 5
-
-
-
100
-
500
-
3 typ
3 typ
Max.
Unit
Note
-
MHz
±50
ppm
±50
ppm
-
ppm
±50
ppm
5
pF
12
pF
-
µW
80
Ω
505
Ohm
(see Note 6) ^oC
-
pF
-
pF
(see Note 1)
(see Note 1)
(see Note 2)
(see Note 3)
(see Note 4)
(see Note 7)
(see Note 7)
 2013-2015 Microchip Technology Inc.
DS00001987A-page 125