SM3-8RG5 Data Sheet #:

TM088

Page 2 of 32

Rev:

07 Date: 09/06/11

© Copyright 2011 The Connor-Winfield Corp. All Rights Reserved

Specifications subject to change without notice

General Description

TheSM3-8RG5timingmoduleprovidesaclockoutputthatmeetsorexceedsStratum3specificationsgiveninGR-1244-CORE

(Issue2),GR-253-CORE(Issue3)andITU-TG.812(option3).TheSM3-8RG5featureseightreferenceinputs.Eachinputwillauto-

detectthefollowingreferencefrequencies:8kHz,1.544MHz,2.048MHz,12.96MHz,19.44MHz,25.92MHz,38.88MHz,51.84MHz

and77.76MHz.

TheSM3-8RG5timingmodulecanbeconfiguredduringproductiontoproduceanoutputupto77.76MHz.Thisoutputisderivedfrom

anonboardVCXOandmustbespecifiedwhenordering.ThesecondoutputisaBITSoutputselectableforeither1.544or2.048MHz.

Themaster/slaveoutputis8KHz.TheusercommunicateswiththeSM3-8RG5modulethroughaSPIport.TheusercontrolstheSM3-

8RG5operationbywritingtotheappropriateregisters.TheusercanalsoenableordisableSPIoperationthroughaSPI_Enablepin.

TheSM3-8RG5offersawiderangeofoptionsforthesystemdesigner.ThebandwidthisSPIPort-selectablefrom0.025Hzto1.6

Hz.0.098HzistherecommendedoperationalbandwidthforStratum3applications.The8kHzoutputhasanadjustablepulsewidth.

Thepull-inrangeisalsoadjustabletoestablishthedesiredreferencefrequencyrejectionlimits.AFreeRunfrequencycalibration

valuecanbewrittentothemoduletoprovideahighdegreeofaccuracyinthefreerunmode.Thereferencefrequencyforanygiven

referenceinputisautomaticallydetected.AwealthofstatusinformationisavailablethroughtheSPIPortregisters.Theuseralsohas

achoicebetweenautonomousorfullmanualcontroloperation.

Inmanualmode,theusercontrolsthemoduleoperatingmodesFreeRun,HoldOverorlockedtoaspecificreference.Ifthe

chosenreferenceisunavailableordisqualifiedthemoduleautomaticallyentersHoldOver.

Inautonomouscontrolmode,operationalmodeselectionoccursautomaticallybasedonreferencepriorityandqualificationstatus.

Whentheactivereferencebecomesdisqualified,themodulewillswitchtoanotherqualifiedreference.Ifnoneisavailable,itwillswitch

toHoldOver.Intherevertivemodethemodulewillseektoacquirethehighestpriorityqualifiedreference.Inthenon-revertivemode

themodulewillnotreturntothepreviousreferenceevenafteritisre-qualifiedunlesstherearenootherqualifiedreferences.

Switchingbetweenreferencesishitless.Likewise,theoutputfrequencyslewrateisminimizedduringanychangeofoperating

mode,includingentryintoandreturnfromFreeRunorHoldOvertoprotecttrafficfromtransient-inducedbiterrors.

ReferenceStatusinformationandtheoperatingmodeinformationisaccessedthroughstatusregisters.Themodulewillsetthe

Interruptpin(SPI_INT)lowtoindicateastatuschange.

FreeRunoperationguaranteesanoutputwithin4.6ppmofnominalfrequencyandHoldOveroperationguaranteestheoutput

frequencywillnotchangebymorethan0.37ppmduringthefirst24hours.Frequencyaccuracyisbasedonaprecisionovento

providethestabiltyrequiredforStratum3compliance.

TheSM3-8RG5canbeprogrammedtostartupinanymodeorbandwidth.Themodulemayevenbeprogrammedtooperateinan

afullyautonomousmodewithnofurtherconfigurationrequired.

Themoduleoperateson3.3V±5%withatypicalpowerdrainoflessthan1.6Watturnon,droppingtoapproximately1W@room

temperatureafterwarmingup.Themoduleoperatesoverthe0°to70°Ccommercialtemperaturerange.

PhasebuildoutcanbeenabledordisabledbymeansoftheSPIport.

Functional Block Diagram

Figure 1

Reference Input Monitor

Control

Mode

Reference

Selection

DPLL

APLL

Reference Priority,

Revertivity and Mask

Table

Bus Interface

EEPROM

DAC

OCXO

VCXO

TRST

TCK

TDO

TDI

TMS

M/S REF

Ref 1 - 8

Reset

MASTER SELECT

T1/E1

SPI_ENBL

SPI_Clk

SPI_In

SPI_Out

SPI_INT

8

Output 1

M/S_OUT

BITS_Clk

LOS

LOL

Hold_Good