LAN9252SLASHML datasheet(320/329 Pages) MICROCHIP

320 / 329 page

LAN9252

DS00001909A-page 320

 2015 Microchip Technology Inc.

18.7

Clock Circuit

The device can accept either a 25 MHz crystal or a 25 MHz single-ended clock oscillator (±50 ppm) input. If the single-

ended clock oscillator method is implemented, OSCO should be left unconnected and OSCI should be driven with a

clock signal that adheres to the specifications outlined throughout Section 18.0, "Operational Characteristics". See

Table 18-12 for the recommended crystal specifications.

Note 27:

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 28:

Frequency Deviation Over Time is also referred to as Aging.

Note 29:

The total deviation for 100BASE-TX is ±50 ppm.

Note 30:

The maximum allowable values for frequency tolerance and frequency stability are application dependent.

Since any particular application must meet the EtherCAT ±25 ppm Total PPM Budget, the combination of

these two values must be approximately ±15 ppm (allowing for aging).

TABLE 18-12: CRYSTAL SPECIFICATIONS

PARAMETER

SYMBOL

MIN

NOM

MAX

UNITS

NOTES

Crystal Cut

AT, typ

Crystal Oscillation Mode

Fundamental Mode

Crystal Calibration Mode

Parallel Resonant Mode

Frequency

Ffund

25.000

MHz

802.3 Frequency Tolerance at

25oC

Ftol

±40

ppm

Note 27

802.3 Frequency Stability Over

Temp

Ftemp

±40

ppm

Note 27

802.3 Frequency Deviation Over

Time

Fage

±3 to 5

ppm

Note 28

802.3 Total Allowable PPM Bud-

get

±50

ppm

Note 29

EtherCAT Frequency Tolerance

at 25oC

Ftol

±15

ppm

Note 30

EtherCAT Frequency Stability

Over Temp

Ftemp

±15

ppm

Note 30

EtherCAT Frequency Deviation

Over Time

Fage

±3 to 5

ppm

Note 28

EtherCAT Total Allowable PPM

Budget

±25

ppm

Note 31

Shunt Capacitance

Load Capacitance

Drive Level

300

Note 32

µW

Equivalent Series Resistance

100

Ω

Operating Temperature Range

Note 33

Note 34

OSCI Pin Capacitance

3 typ

Note 35

OSCO Pin Capacitance

3 typ

Note 35

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