SM802121UMGTR Ver la hoja de datos (PDF) - Micrel

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componentes Descripción

Fabricante

SM802121UMGTR

ClockWorks™ 10GbE (156.25MHz), Ultra-Low Jitter, LVPECL Frequency Synthesizer

Micrel 

Micrel, Inc.

SM802121

Pin Description

Pin Number

16, 17

1, 18

2, 22

Pin Name

/Q, Q

VDDO

VSSO

6

XTAL_SEL

3, 4, 20, 21,

23, 24

5, 7, 12, 15, 19

8

13, 14

9

10

11

NC

TEST

VDD

VSS

(Exposed Pad)

REF_IN

XIN

XOUT

Pin Type

O, (DIF)

PWR

PWR

I, (SE)

PWR

PWR

I, (SE)

I, (SE)

O, (SE)

Pin Level

LVPECL

LVCMOS

LVCMOS

crystal

crystal

Pin Function

Differential Clock Output 156.25MHz.

Power Supply for Output.

Power Supply Ground for Output.

Selects PLL Input Reference Source (0 = REF_IN, 1 =

XTAL, 45KΩ pull-up).

No Connect. Do not connect anything to these pins.

Factory Test Pins. Do not connect anything to these pins.

Core Power Supply.

Core Power Supply Ground. The exposed pad must be

connected to the VSS ground plane.

Reference Clock Input.

Crystal Reference Input. No load caps needed. (See Fig. 5)

Crystal Reference Output. No load caps needed. (See Fig. 5)

Application Information

Input Reference

When operating with a crystal input reference, do not

apply a switching signal to REF_IN.

Crystal Layout

Keep the layers under the crystal as open as possible

and do not place switching signals or noisy supplies

under the crystal.

Crystal load capacitance is built inside the die so no

external capacitance is needed. See the Selecting a

quartz crystal for the Clockworks Flex I Family of

Precision Synthesizers application note for further

details.

Contact Micrel’s HBW applications group if you need

assistance on selecting a suitable crystal for your

application at hbwhelp@micrel.com

Truth Table

XTAL_SEL

0

1

INPUT

REF_IN

XTAL

January 2012

3

M9999-011212-A

hbwhelp@micrel.com or (408) 955-1690

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