Datasheet

 2016 Microchip Technology Inc. DS00002165B-page 65
LAN8720A/LAN8720AI
Note 5-31 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).
Note 5-32 Frequency Deviation Over Time is also referred to as Aging.
Note 5-33 The total deviation for the Transmitter Clock Frequency is specified by IEEE 802.3u as 
±100 PPM.
Note 5-34 The crystal must support 100uW operation to utilize this circuit.
Note 5-35 0
o
C for extended commercial version, -40
o
C for industrial version.
Note 5-36 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.
Equivalent Series Resistance R
1
— — 80 Ohm —
XTAL2 Series Resistor R
s
495 500 505 Ohm —
Operating Temperature Range — Note 5-35 — +85
o
C —
XTAL1/CLKIN Pin Capacitance — — 3 typ — pF Note 5-36
XTAL2 Pin Capacitance — — 3 typ — pF Note 5-36
TABLE 5-14: 100UW 25MHZ CRYSTAL SPECIFICATIONS (CONTINUED)
Parameter Symbol Min Nom Max Units Notes