LAN9514 datasheet(45/54 Pages) MICROCHIP

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DS00002306A-page 45

LAN9514/LAN9514I

4.6

Clock Circuit

LAN9514/LAN9514i can accept either a 25MHz crystal (preferred) or a 25MHz single-ended clock oscillator (+/- 50ppm)

input. If the single-ended clock oscillator method is implemented, XO should be left unconnected and XI should be

driven with a nominal 0-3.3V clock signal. The input clock duty cycle is 40% minimum, 50% typical and 60% maximum.

It is recommended that a crystal utilizing matching parallel load capacitors be used for the crystal input/output signals

(XI/XO). See Table 4-10 for the recommended crystal specifications.

TABLE 4-9:

JTAG TIMING VALUES

Symbol

Description

Min

Max

Units

Notes

ttckp

TCK clock period

66.67

—

ttckhl

TCK clock high/low time

ttckp*0.4

ttckp*0.6

—

tsu

TDI, TMS setup to TCK rising edge

—

TDI, TMS hold from TCK rising edge

—

tdov

TDO output valid from TCK falling edge

—

tdoh

TDO output hold from TCK falling edge

—

TABLE 4-10:

LAN9514/LAN9514I 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

—

Frequency Tolerance @ 25°C

Ftol

—

+/-50

PPM

Note 4-13

Frequency Stability Over Temp

Ftemp

—

+/-50

PPM

Note 4-13

Frequency Deviation Over Time

Fage

—

+/-3 to 5

—

PPM

Note 4-14

Total Allowable PPM Budget

—

+/-50

PPM

Note 4-15

Shunt Capacitance

—7 typ—

—

Load Capacitance

—

20 typ

—

Drive Level

300

—

Equivalent Series Resistance

——

Ω

—

Operating Temperature Range

Note 4-16

—

Note 4-17

°C

—

LAN9514/LAN9514i XI Pin

Capacitance

—3 typ—

Note 4-18

LAN9514/LAN9514i XO Pin

Capacitance

—3 typ—

Note 4-18

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