USB84604 datasheet(51/61 Pages) MICROCHIP

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 2014-2016 Microchip Technology Inc.

DS60001295C-page 51

USB84604

9.7

Clock Specifications

The device can accept either a 24 MHz crystal or a 24 MHz single-ended clock oscillator input. If the single-ended clock

oscillator method is implemented, XTAL1 should be left unconnected and REFCLK should be driven with a clock that

adheres to the specifications outlined in Section 9.7.2, "External Reference Clock (REFCLK)".

9.7.1

OSCILLATOR/CRYSTAL

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

(XTAL1I/XTAL2). See Table 9-13 for the recommended crystal specifications.

9.7.2

EXTERNAL REFERENCE CLOCK (REFCLK)

The following input clock specifications are suggested:

• 50% duty cycle

 10%

• 24 MHz

 350 PPM

TABLE 9-13:

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

24.000

MHz

Total Allowable PPM Budget

+/-350

PPM

Operating Temperature Range

Note 11

Note 12

°C

Note 11: -40 °C for automotive version.

Note 12: +85 °C for automotive version.

Note:

The external clock is recommended to conform to the signalling levels designated in the JEDEC specifica-

tion on 1.2 V CMOS Logic although maximum values of 3.6 V are stated in Section 9.1, "Absolute Maxi-

mum Ratings*," on page 40 and in Table 9-8, “DC Electrical Characteristics,” on page 46. XTAL2 should

be treated as a no connect when an external clock is supplied.

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