W5100S datasheet(96/110 Pages) WIZNET

96 / 110 page

96 / 110

W5100S Datasheet Version1.2.5

Clock & Transformer Requirements

6.1

Quartz Crystal requirements.

Table 8 Quartz Crystal

Parameter

Condition / Description

Min

Typ

Max

Unit

Frequency(F)

MHz

Frequency Tolerance

At 25

C

-50

+50

ppm

Frequency Stability

1 Year aging.

-50

+50

ppm

Load capacitance(CL)

ESR = 30 Ω

Feedback Resistor(RF)

External resistor

Ω

Startup time

W5100S Reset

Trans-conductance(gm)

16.7

mA/V

gain margin (gainmargin)

gainmargin = gm / gmcrit

6.99

C0(1) : The Packaging Parasitic Shunt Capacitance.

CL(1) : Load Capacitance. eq) CL = (CL1 X CL2) / (CL1 X CL2) + Cs

CL1 , CL2 : External Capacitances of the circuit connected to the crystal (Typically, CL1 = CL2)

Cs : Stray Capacitance of printed circuit board and connections.

gmcrit : Oscillator loop critical gain. eq) gmcrit = 4 × (ESR + RExt) × (2πF)2 × (C0 + CL)2

ESR(1) : Maximal equivalent series resistance. eq) ESR = Rm X ( 1 + C0/CL)2

RExt : Resistor for limiting the drive level(DL) of the crystal.

DL(1) : The power dissipated in the crystal. Excess power can destroy the crystal.

RF(2) : Feedback resistor.

⚫

C0, CL, ESR and DL are provided by the crystal manufacturer.

⚫

The W5100S has no feedback resistor. Therefore, it must be inserted outside

* Crystal circuit is modeled as below Figure 23.

CL2

CL1

XTAL Model (

)

RExt

W5100S

XSCO

XSCI

CLK_25M

Figure 23 Quartz Crystal Model

W5100S Datasheet(PDF) 96 Page - WIZnet Co., Ltd

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