TUSB9261

www.ti.com

SLLSE67B

– MARCH 2011 – REVISED MAY 2011

6.3

Oscillator

XI should be tied to the 1.8-V clock source and XO should be left floating.

VSSOSC should be connected to the PCB ground plane.

A 20-, 25-, 30- or 40-MHz clock can be used.

Table 6-1. Oscillator Specification

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNIT

XI input capacitance

0.414

pF

Low-level input voltage

0.7

V

High-level input voltage

1.05

V

Frequency tolerance

Operational temperature

–50

50

ppm

Duty cycle

45

50

55

%

Rise/Fall time

20% - 80 %

6

ns

0.8

ps

25

ps

Reference clock jitter

50

ps

(1)

Sigma value assuming Gaussian distribution

(2)

After application of JTF

(3)

(4)

Absolute phase jitter (p-p)

6.4

Crystal

A parallel, 20-pF load capacitor should be used if a crystal source is used.

VSSOSC should not be connected to the PCB ground plane.

A 20-, 25-, 30- or 40-MHz crystal can be used.

Table 6-2. Crystal Specification

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNIT

Oscillation mode

Fundamental

20

25

Oscillation frequency

MHz

30

40

20 MHz and 25 MHz

50

ESR

Equivalent series resistance

30 MHz

40

Ω

40 MHz

30

Frequency tolerance

Operational temperature

±50

ppm

Frequency stability

1 year aging

±50

ppm

Load capacitance

12

20

24

pF

Crystal and board stray

4.5

pF

capacitance

Drive level (max)

0.8

mW

Copyright

© 2011, Texas Instruments Incorporated

CLOCK CONNECTIONS

17

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