8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
1
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
GENERAL DESCRIPTION
The ICS8442 is a general purpose, dual output
Crystal-to-Differential LVDS High Frequency
Synthesizer and a member of the HiPerClockS™
family of High Performance Clock Solutions from
ICS. The ICS8442 has a selectable TEST_CLK
or crystal input. The TEST_CLK input accepts LVCMOS or
LVTTL input levels and translates them to LVDS levels. The
VCO operates at a frequency range of 250MHz to 700MHz. The
VCO frequency is programmed in steps equal to the value of
the input reference or crystal frequency. The VCO and output
frequency can be programmed using the serial or parallel inter-
face to the configuration logic. The low phase noise characteris-
tics of the ICS8442 makes it an ideal clock source for Gigabit
Ethernet and Sonet applications.
BLOCK DIAGRAM PIN ASSIGNMENT
FEATURES
•Dual differential LVDS outputs
•Selectable crystal oscillator interface or
LVCMOS/LVTTL TEST_CLK
•Output frequency range: 31.25MHz to 700MHz
•Crystal input frequency range: 10MHz to 25MHz
•VCO range: 250MHz to 700MHz
•Parallel or serial interface for programming counter
and output dividers
•RMS period jitter: 2.7ps (typical)
•Cycle-to-cycle jitter: 18ps (typical)
•3.3V supply voltage
•0°C to 85°C ambient operating temperature
•“Lead-Free” package available
32 31 30 29 28 27 26 25
9 10 11 12 13 14 15 16
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
XTAL1
TEST_CLK
XTAL_SEL
VDDA
S_LOAD
S_DATA
S_CLOCK
MR
M5
M6
M7
M8
N0
N1
nc
GND
GND
nFOUT0
FOUT0
VDD
nFOUT1
FOUT1
VDD
TEST
XTAL2
nP_LOAD
VCO_SEL
M0
M1
M2
M3
M4
32-Lead LQFP
7mm x 7mm x 1.4mm package body
Y Package
Top View
ICS8442
HiPerClockS™
ICS
OSC
VCO_SEL
XTAL_SEL
TEST_CLK
XTAL1
XTAL2
S_LOAD
S_DATA
S_CLOCK
nP_LOAD
M0:M8
N0:N1
VCO
PLL
FOUT0
nFOUT0
FOUT1
nFOUT1
TEST
CONFIGURATION
INTERFACE
LOGIC
÷ M
0
1
0
1
PHASE DETECTOR ÷ 1
÷ 2
÷ 4
÷ 8
MR
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
2
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
cific default state that will automatically occur during power-
up. The TEST output is LOW when operating in the parallel
input mode. The relationship between the VCO frequency, the
crystal frequency and the M divider is defined as follows:
The M value and the required values of M0 through M8 are
shown in Table 3B, Programmable VCO Frequency Function
Table. Valid M values for which the PLL will achieve lock for a
25MHz reference are defined as 10 ≤ M ≤ 28. The frequency
out is defined as follows:
Serial operation occurs when nP_LOAD is HIGH and S_LOAD
is LOW. The shift register is loaded by sampling the S_DATA
bits with the rising edge of S_CLOCK. The contents of the
shift register are loaded into the M divider and N output di-
vider when S_LOAD transitions from LOW-to-HIGH. The M
divide and N output divide values are latched on the HIGH-to-
LOW transition of S_LOAD. If S_LOAD is held HIGH, data at
the S_DATA input is passed directly to the M divider and N
output divider on each rising edge of S_CLOCK. The serial
mode can be used to program the M and N bits and test bits
T1 and T0. The internal registers T0 and T1 determine the state
of the TEST output as follows:
NOTE: The functional description that follows describes op-
eration using a 25MHz crystal. Valid PLL loop divider values
for different crystal or input frequencies are defined in the In-
put Frequency Characteristics, Table 5, NOTE 1.
The ICS8442 features a fully integrated PLL and therefore
requires no external components for setting the loop band-
width. A fundamental crystal is used as the input to the on-
chip oscillator. The output of the oscillator is fed into the phase
detector. A 25MHz crystal provides a 25MHz phase detector
reference frequency. The VCO of the PLL operates over a
range of 250MHz to 700MHz. The output of the M divider is
also applied to the phase detector.
The phase detector and the M divider force the VCO output fre-
quency to be M times the reference frequency by adjusting the
VCO control voltage. Note that for some values of M (either too
high or too low), the PLL will not achieve lock. The output of the
VCO is scaled by a divider prior to being sent to each of the
LVDS output buffers. The divider provides a 50% output duty cycle.
The programmable features of the ICS8442 support two input
modes to program the M divider and N output divider. The two
input operational modes are parallel and serial.
Figure 1
shows
the timing diagram for each mode. In parallel mode, the
nP_LOAD input is initially LOW. The data on inputs M0 through
M8 and N0 and N1 is passed directly to the M divider and
N output divider. On the LOW-to-HIGH transition of the
nP_LOAD input, the data is latched and the M divider remains
loaded until the next LOW transition on nP_LOAD or until a
serial event occurs. As a result, the M and N bits can be
hardwired to set the M divider and N output divider to a spe-
FUNCTIONAL DESCRIPTION
fVCO = fxtal x M
T1 T0 TEST Output
0 0 LOW
0 1 S_Data, Shift Register Input
1 0 Output of M divider
1 1 CMOS FOUT
FIGURE 1. PARALLEL & SERIAL LOAD OPERATIONS
Time
S
ERIAL
L
OADING
P
ARALLEL
L
OADING
M, N
t
S
t
H
t
S
t
H
t
S
S_CLOCK
S_DATA
S_LOAD
nP_LOAD
M0:M8, N0:N1
nP_LOAD
*NOTE: The NULL timing slot must be observed.
T1 T0
*
NULL
N1 N0 M8 M7 M6 M5 M4 M3 M2 M1 M0
FOUT = fVCO = fxtal x M
NN
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
3
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
TABLE 1. PIN DESCRIPTIONS
rebmuNemaNepyTnoitpircseD
15MtupnIpulluP
noitsisnartHGIH-ot-WOLnodehctalataD.stupniredividM
.slevelecafretniLT
TVL/SOMCVL.tupniDAOL_Pnfo
,4,3,2
,92,82
23,13,03
,8M,7M,6M
,1M,0M
4M,3M,2M
tupnInwodlluP
6,51N,0NtupnInwodlluP C3e
lbaTnidenifedsaeulavredividtuptuosenimreteD
.slevelecafretniLTTVL/SOMCVL.elbaTnoitcnuF
7cndesunU.tcennocoN
61,8DNGrewoP.dnuorgylppusrewoP
9TSETtuptuO tuptuO.noitarepofoedomlairesehtniEVITCAsihcihwtuptuotseT
.slevelec
afretniLTTVL/SOMCVL.edomlellarapniWOLnevird
31,01V
DD
rewoP.snipylppuseroC
21,111TUOFn,1TUOFtuptuO .slevelecafretniSDVL.rezisehtnysehtroftuptuolaitnereffiD
51,410
TUOFn,0TUOFtuptuO .slevelecafretniSDVL.rezisehtnysehtroftuptuolaitnereffiD
71RMtupnInwodlluP
sredividlanretn
ieht,HGIHcigolnehW.teseRretsaMhgiHevitcA
detrevniehtdnawologotxTUOFstuptuoeurtehtgnisuacteserera
sredividlanretnieht,WOLcigolnehW.hgihogotxTUOFnstuptuo
dedaoltceffetonseodRMfonoitressA.delbaneerastuptuoeht
dna
.slevelecafretniLTTVL/SOMCVL.seulavTdna,N,M
81KCOLC_StupnInwodlluP retsigertfihsehtotnitupniATAD_Statne
serpatadlairesniskcolC
.slevelecafretniLTTVL/SOMCVL.KCOLC_Sfoegdegnisirehtno
91ATAD_StupnInwodlluP egdegnisirehtnodelpmasataD.tupnilairesretsigertfihS
.slevelecafretniLTTVL/SOMCVL.KCOLC_Sfo
02DAOL_StupnInwodlluP .s
redividehtotniretsigertfihsmorfatadfonoitisnartslortnoC
.slevelecafretniLTTVL/SOMCVL
12V
ADD
rewoP.nipylppusgolanA
22LES_LATXtupnIpulluP
ecnereferLLPehtsastupnitsetrorotallicsolatsyrcneewtebstceleS
neh
wKLC_TSETstceleS.HGIHnehwstupniLATXstceleS.ecruos
.slevelecafretniLTTVL/SOMCVL.WOL
32KLC_TSETtupnInwodlluP.
slevelecafretniLTTVL/SOMCVL.tupnikcolctseT
52,422LATX,1LATXtupnI .tuptuoehtsi2LATXtupniehtsi1LATX.ecafret
nirotallicsolatsyrC
62DAOL_PntupnInwodlluP
si0M:8MtatneserpatadnehwsenimreteD.tupnidaollellaraP
ehtstes0N:1
Ntatneserpatadnehwdna,redividMotnidedaol
.slevelecafretniLTTVL/SOMCVL.eulavredividtuptuoN
72LES_OCVtupnIpu
lluP .edomssapybroLLPnisirezisehtnysrehtehwsenimreteD
.slevelecafretniLTTVL/SOMCVL
:ETON
pulluP
dna
nwodlluP
.seulavlacipytrof,scitsiretcarahCniP,2elbaTeeS.srotsisertupnilanretniotrefer
TABLE 2. PIN CHARACTERISTICS
lobmySretemaraPsnoitidnoCtseTmuminiMlacipyTmumixaMstinU
C
NI
ecnaticapaCtupnI 4Fp
R
PULLUP
rotsiseRpulluPtupnI 15KΩ
R
NWODLLUP
rotsiseRnwodlluPtupnI 15KΩ
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
4
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
TABLE 3A. PARALLEL AND SERIAL MODE FUNCTION TABLE
TABLE 3B. PROGRAMMABLE VCO FREQUENCY FUNCTION TABLE
TABLE 3C. PROGRAMMABLE OUTPUT DIVIDER FUNCTION TABLE
stupnI eulaVrediviDN )zHM(ycneuqerFtuptuO
1N0NmuminiMmumixaM
00 1 052007
01 2 521053
10 4 5.26571
11 8 52.135.78
ycneuqerFOCV
)zHM( ediviDM 6528214623618421
8M7M6M5M4M3M2M1M0M
05201 0 0 0 0 0 10 10
57211 00000 1011
• • •••••••••
• • •••••••••
05662 0 0 0 0 1 10 10
57672 000011011
00782 0000 11100
ycneuqerftupniKLC_TSETrolatsyrcotdnops
errocseicneuqerfgnitluserehtdnaseulavedividMesehT:1ETON
.zHM52fo
stupnI snoitidnoC
RMDAOL_PnMNDAOL_SKCOLC_SATAD_S
HX XXX X X
laitnereffidaotstuptuoehtsecrof,HGIHnehW.teseR
tub,)HGIH=xTUO
FndnaWOL=xTUOF(etatsWOL
.seulavTdna,N,Mdedaoltceffetonseod
LL ataDataDX X X MehtotyltceriddessapstupniNdnaMnoataD
.WOLdecroftuptuoTSET.redividtuptuoNdnaredivid
L↑ataDataDL X X dedaolsniamerdnasretsigertupniotnidehctalsiataD
.sruccotnevelairesalitnuronoitisnartWOLtxenlitnu
LH XXL ↑ataD noatadhtiwdedaolsiretsigertfihS.edomtupnilaireS
.KCOLC_SfoegdegnisirhcaenoATAD_S
LH XX↑LataD ehtotdessaperaretsigertfihsehtfostnetnoC
.redividtuptuoNdnarediv
idM
LH XX↓LataD.dehctaleraseulavredividtuptuoNdnaredividM
LH XXL X X .sretsigertfihstceffatonodtupnilairesrolellaraP
LH XXH ↑at
aD.dekcolcsitisaredividMotyltceriddessapATAD_S
WOL=L:ETON
HGIH=H
eract'noD=X
↑noitisnartegdegnisiR=
↓noitis
nartegdegnillaF=
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
5
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
TABLE 4A. POWER SUPPLY DC CHARACTERISTICS, VDD = VDDA = 3.3V±5%, TA = 0°C TO 85°C
TABLE 4B. LVCMOS / LVTTL DC CHARACTERISTICS, VDD = VDDA = 3.3V±5%, TA = 0°C TO 85°C
lobmySretemaraPsnoitidnoCtseTmuminiMlacipyTmumixaMstinU
V
DD
egatloVylppuSeroC 531.33.3564.3V
V
ADD
egatloVylppuSgolanA 531.33.3564.3V
I
DD
tnerruCylppuSrewoP 551Am
I
ADD
tnerruCylppuSgolanA 02Am
lobmySretemaraPsnoitidnoCtseTmuminiMlacipyTmumixaMstinU
V
HI
tupnI
egatloVhgiH
,DAOL_Pn,RM,1N,0N,8M-0M
,DAOL_S,ATAD_S,KCOLC_S
LES_OCV,LES_LATX
2V
DD
3.0+V
KLC_TSET2V
DD
3.0+V
V
LI
tupnI
egatloVwoL
,DAOL_Pn,RM,1N,0N,8M-0M
,DAOL_S,ATAD_S,KCOLC_S
LES_OCV,LES_LATX
3.0-8.0V
KLC_TSET3.0-3.1V
I
HI
tupnI
tnerruChgiH
,RM,1N,0N,8M-6M,4M-0M
,ATAD_S,KCOLC_S,DAOL_Pn
,DAOL_S
V
DD
V=
NI
V564.3=051Aµ
LES_OCV,LES_LATX,5MV
DD
V=
NI
V564.3=5
I
LI
tupnI
tnerruCwoL
,RM,1N,0N,8M-6M,4M-0M
,ATAD_S,KCOLC_S,DAOL_Pn
,DAOL_S
V
DD
,V564.3=
V
NI
V0= 5-Aµ
LES_OCV,LES_LATX,5M V
DD
,V564.3=
V
NI
V0= 051-
V
HO
tuptuO
egatloVhgiH 1ETON;TSET6.2V
V
LO
tuptuO
egatloVwoL 1ETON;TSET 5.0V
05htiwdetanimretstuptuO:1ETON ΩVot
DD
,noitcesnoitamrofnItnemerusaeMretemaraPeeS.2/
."tiucriCtseTdaoLtuptuOV3.3"
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
DD 4.6V
Inputs, VI-0.5V to VDD + 0.5V
Outputs, IO
Continuous Current 10mA
Surge Current 15mA
Package Thermal Impedance, θJA 47.9°C/W (0 lfpm)
Storage Temperature, T
STG -65°C to 150°C
NOTE: Stresses beyond those listed under Absolute
Maximum Ratings may cause permanent damage to the
device. These ratings are stress specifications only. Functional
operation of product at these conditions or any conditions be-
yond those listed in the
DC Characteristics
or
AC Character-
istics
is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect product reliability.
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
6
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
TABLE 4C. LVDS DC CHARACTERISTICS, VDD = VDDA = 3.3V±5%, TA = 0°C TO 85°C
TABLE 5. INPUT FREQUENCY CHARACTERISTICS, VDD = VDDA = 3.3V±5%, TA = 0°C TO 85°C
lobmySretemaraPsnoitidnoCtseTmuminiMlacipyTmumixaMstinU
f
NI
ycneuqerFtupnI
1ETON;KLC_TSET0152zHM
1ETON;2LATX,1LATX0152zHM
KCOLC_S 05zHM
ehtnihtiwetarepootOCVehtroftesebtsume
ulavMehtegnarycneuqerfKLC_TSETdnalatsyrctupniehtroF:1ETON
52eraMfoseulavdilavzHM01foycneuqerftupnimumi
nimehtgnisU.egnarzHM007otzHM052 ≤M≤ehtgnisU.07
01eraMfoseulavdilavzHM52foycneuqerfmumixam ≤M≤.82
TABLE 6. CRYSTAL CHARACTERISTICS
retemaraPsnoitidnoCtseTmuminiMlacipyTmumixaMstinU
noitallicsOfoedoM latnemadnuF
ycneuqerF 0152zHM
)RSE(ecnatsiseR
seireStnelaviuqE 05 Ω
ecnaticapaCtnuhS 7Fp
lobmySretemaraPsnoitidnoCtseTmuminiMlacipyTmumixaMstinU
F
TUO
ycneuqerFtuptuO 52.13007zHM
t
)cc(tij3,1ETON;rettiJelcyC-ot-elcyC ijzHM0538182sp
zHM053<ƒ7254sp
t
)rep(tij3,1ETON;SMR,rettiJdoireP 7.27sp
t
)o(ks3,2ETON;wekStuptuO 51sp
t
R
t/
F
emiTllaF/esiRtuptuO%08ot%02051056sp
t
S
emiTputeS
DAOL_PnotN,M5sn
KCOLC_SotATAD_S5sn
DAOL_SotKCOLC_S5sn
t
H
emiTdloH
DAOL_PnotN,M5sn
KCOLC_SotATAD_S5sn
DAOL_SotKCOLC_S5sn
cdoelcyCytuDtuptuO1>N8425%
t
WP
htdiWesluPtuptuO1=Nt
doireP
051-2/t
doireP
051+2/sp
t
KCOL
emiTkcoLLLP 1sm
.noitcesnoitamrofnItnemerusaeMretemaraPeeS
.stupniLATXgnisuecnamrofreprettiJ:1ETON
.snoiti
dnocdaollauqehtiwdnaegatlovylppusemasehttastuptuoneewtebwekssadenifeD:2ETON
.stniopssorclaitnereffidtu
ptuoehttaderusaeM
.56dradnatSCEDEJhtiwecnadroccanidenifedsiretemarapsihT:3ETON
TABLE 7. AC CHARACTERISTICS, VDD = VDDA = 3.3V±5%, TA = 0°C TO 85°C
lobmySretemaraPsnoitidnoCtseTmuminiMlacipyTmumixaMstinU
V
DO
egatloVtuptuOlaitnereffiD 052054006Vm
∆V
DO
V
DO
egnahCedutingaM 05Vm
V
SO
egatloVtesffO 521.14.16.1V
∆V
SO
V
SO
egnahCedutingaM 05Vm
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
7
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
PARAMETER MEASUREMENT INFORMATION
OUTPUT SKEW
odc & tPERIOD
Cycle-to-Cycle Jitter Period Jitter
VOH
VREF
VOL
Mean Period
(First edge after trigger)
Reference Point
(Trigger Edge)
1σ contains 68.26% of all measurements
2σ contains 95.4% of all measurements
3σ contains 99.73% of all measurements
4σ contains 99.99366% of all measurements
6σ contains (100-1.973x10-7)% of all measurements
Histogram
OUTPUT RISE/FALL TIME
Clock
Outputs 20%
80% 80%
20%
t
R
t
F
V
SWING
Pulse Width
t
PERIOD
t
PW
t
PERIOD
odc =
nFOUT0, nFOUT1
FOUT0, FOUT1
➤
➤
➤
➤
nFOUT0,
nFOUT1
FOUT0,
FOUT1
t
sk(o)
nFOUTx
FOUTx
nFOUTy
FOUTy
VOS / ∆∆
∆∆
∆VOS SETUP
VOD / ∆∆
∆∆
∆VOD SETUP
3.3V OUTPUT LOAD TEST CIRCUIT
out
out
LVDS
DC Input
➤
➤
➤
V
OS
/∆ V
OS
V
DD
➤
➤
➤
100
out
out
LVDS
DC Input V
OD
/∆ V
OD
V
DD
SCOPE
Qx
nQx
LVDS
3.3V±5%
Power Supply
+-
Float GND
t
cycle n
t
cycle n+1
t
jit(cc) =
t
cycle n –
t
cycle n+1
1000 Cycles
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
8
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
STORAGE AREA NETWORKS
A variety of technologies are used for interconnection of the
elements within a SAN. The tables below lists the common fre-
Table 8. Common SANs Application Frequencies
Table 9. Configuration Details for SANs Applications
APPLICATION INFORMATION
ygolonhceTtcennocretnIetaRkcolC SEDRESotycneuqerFecnerefeR
)zHM(
ycneuqerFlatsyrC
)zHM(
tenrehtEtibagiGzHG52
.152.651,052,52152135.91,52
lennahCerbiF zHG5260.11CF
zHG0521.22CF 5218.231,521.35,52.60152,5265106.61
dnabinifnIzHG5.2052,52152
As in any high speed analog circuitry, the power supply pins
are vulnerable to random noise. The ICS8442 provides sepa-
rate power supplies to isolate any high switching noise from
the outputs to the internal PLL. VDD and VDDA, should
be individually connected to the power supply plane through
vias, and bypass capacitors should be used for each pin. To
achieve optimum jitter performance, better power supply
isolation is required.
Figure 2
illustrates how a 10Ω along
|with a 10µF and a .01µF bypass capacitor should be
connected to each VDDA pin.
POWER SUPPLY FILTERING TECHNIQUES
FIGURE 2. POWER SUPPLY FILTERING
10Ω
VDDA
10µF
.01µF
3.3V
.01µF
VDD
tcennocretnI
ygolonhceT
ycneuqerFlatsyrC
)zHM(
2448SCI
ycneuqerFtuptuO
SEDRESot
)zHM(
2448SCI
sgnitteSN&M
8M7M6M5M4
M3M2M1M0M1N0N
tenrehtEtibagiG
52521 0000 10100 10
52052 0000 101000 1
5252.651 0000 1100 110
52135.9152.651 000 100000 10
1lennahCrebiF
52521.35 00001000 111
5252.601 0000 1000 110
2lennahCrebiF5265106.61521
8.231 000 100000 10
dnabinifnI
52521 0000 10100 10
52052 0000 101000 1
quencies used as well as the settings for the ICS8442 to gener-
ate the appropriate frequency.
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
9
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
CRYSTAL INPUT INTERFACE
A crystal can be characterized for either series or parallel mode
operation. The ICS8442 has a built-in crystal oscillator circuit.
This interface can accept either a series or parallel crystal without
additional components and generate frequencies with accuracy
Figure 3. CRYSTAL INPUt INTERFACE
C2
22p
C1
18p
X1
18pF Parallel Crystal
ICS8442
25
24
XTAL2
XTAL1
suitable for most applications. Additional accuracy can be
achieved by adding two small capacitors C1 and C2 as shown in
Figure 3
. Typical results using parallel 18pF crystals are shown
in Table 10.
LVDS DRIVER TERMINATION
A general LVDS interface is shown in
Figure 4.
In a 100Ω differ-
ential transmission line environment, LVDS drivers require a
matched load termination of 100Ω across near the receiver in-
put. For a multiple LVDS outputs buffer, if only partial outputs
are used, it is recommended to terminate the un-used outputs.
100ΩΩ
ΩΩ
Ω Differential Transmission Line
3.3V
3.3V
LVDS_DRIVER
R1
100
HiPerClockS
Zo = 50 Ohm
Zo = 50 Ohm
nCLK
CLK
FIGURE 4. TYPICAL LVDS DRIVER TERMINATION
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
10
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
The schematic of the ICS8442 layout example used in this layout
guideline is shown in
Figure 5A.
The ICS8442 recommended PCB
board layout for this example is shown in
Figure 5B.
This layout
example is used as a general guideline. The layout in the actual
LAYOUT GUIDELINE
FIGURE 5A. RECOMMENDED SCHEMATIC LAYOUT
U1
ICS8442
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
32
31
30
29
28
27
26
25
M5
M6
M7
M8
N0
N1
nc
GND
TEST
VDD
FOUT1
nFOUT1
VDD
FOUT0
nFOUT0
GND
MR
S_CLOCK
S_DATA
S_LOAD
VDDA
nXTAL_SEL
T_CLK
XTAL1
M4
M3
M2
M1
M0
VCO_SEL
nP_LOAD
XTAL2
VDDA
VDD
Zo = 50 Ohm
TL1 +
-
VDD
nFOUT0
R7
10
X1
Zo = 50 Ohm
TL1N
R2
100
R1
100
+
-
C2
C15
0.1u
FOUT1
C14
0.1u
C16
10u
C11
0.01u
VDD
nFOUT1
Zo = 50 Ohm
TL2
FOUT0
Zo = 50 Ohm
TL2N
C1
system will depend on the selected component types, the den-
sity of the components, the density of the traces, and the stack
up of the P.C. board.
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
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Integrated
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ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
The following component footprints are used in this layout
example: All the resistors and capacitors are size 0603.
POWER AND GROUNDING
Place the decoupling capacitors C14 and C15 as close as pos-
sible to the power pins. If space allows, placing the decoupling
capacitor at the component side is preferred. This can reduce
unwanted inductance between the decoupling capacitor and the
power pin generated by the via.
Maximize the pad size of the power (ground) at the decoupling
capacitor. Maximize the number of vias between power (ground)
and the pads. This can reduce the inductance between the power
(ground) plane and the component power (ground) pins.
If VDDA shares the same power supply with VDD, insert the RC
filter R7, C11, and C16 in between. Place this RC filter as close
to the VDDA as possible.
CLOCK TRACES AND TERMINATION
The component placements, locations and orientations should
be arranged to achieve the best clock signal quality. Poor clock
signal quality can degrade the system performance or cause
system failure. In the synchronous high-speed digital system,
the clock signal is less tolerable to poor signal quality than other
signals. Any ringing on the rising or falling edge or excessive ring
back can cause system failure. The trace shape and the trace
delay might be restricted by the available space on the board and
the component location. While routing the traces, the clock signal
traces should be routed first and should be locked prior to routing
other signal traces.
• The traces with 50Ω transmission lines TL1 and TL2 at
FOUT and nFOUT should have equal delay and run ad-
jacent to each other. Avoid sharp angles on the clock trace.
Sharp angle turns cause the characteristic impedance to
change on the transmission lines.
• Keep the clock trace on same layer. Whenever possible,
avoid any vias on the clock traces. Any via on the trace
can affect the trace characteristic impedance and hence
degrade signal quality.
• To prevent cross talk, avoid routing other signal traces in
parallel with the clock traces. If running parallel traces is
unavoidable, allow more space between the clock trace
and the other signal trace.
• Make sure no other signal trace is routed between the
clock trace pair.
The matching termination resistors R1 and R2 should be located
as close to the receiver input pins as possible. Other termination
scheme can also be used but is not shown in this example.
CRYSTAL
The crystal X1 should be located as close as possible to the pins
24 (XTAL1) and 25 (XTAL2). The trace length between the X1
and U1 should be kept to a minimum to avoid unwanted parasitic
inductance and capacitance. Other signal traces should not be
routed near the crystal traces.
FIGURE 5B. PCB BOARD LAYOUT FOR ICS8442
VDD
TL1
C15
C14
R1
Same requirement f
o
FOUT1/nFOUT1
VDDA
Close to the input
pins of the
receiver
R7
X1
C2
For FOUT0/n FOUT
0
output TL1, TL1N ar
e
50 Ohm traces and
equal length
VIA
GND
TL1N
TL1
PIN 1
U1
C1
TL1N
C11 C16
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
12
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
RELIABILITY INFORMATION
TRANSISTOR COUNT
The transistor count for ICS8442 is: 3662
TABLE 10. θJAVS. AIR FLOW TABLE FOR 32 LEAD LQFP
θθ
θθ
θJA by Velocity (Linear Feet per Minute)
0 200 500
Single-Layer PCB, JEDEC Standard Test Boards 67.8°C/W 55.9°C/W 50.1°C/W
Multi-Layer PCB, JEDEC Standard Test Boards 47.9°C/W 42.1°C/W 39.4°C/W
NOTE: Most modern PCB designs use multi-layered boards. The data in the second row pertains to most designs.
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
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Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
PACKAGE OUTLINE - Y SUFFIX FOR 32 LEAD LQFP
TABLE 11. PACKAGE DIMENSIONS
Reference Document: JEDEC Publication 95, MS-026
NOITAIRAVCEDEJ
SRETEMILLIMNISNOISNEMIDLLA
LOBMYS
ABB
MUMINIMLANIMONMUMIXAM
N23
A----06.1
1A 50.0--51.0
2A 53.104.154.1
b03.073.054.0
c90.0--02.0
DCISAB00.9
1D CISAB00.7
2D .feR06.5
ECISAB00.9
1E CISAB00.7
2E .feR06.5
eCISAB08.0
L54.006.057.
0
θθ
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°
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°
ccc ----01.0
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
14
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
TABLE 12. ORDERING INFORMATION
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems, Incorporated (ICS) assumes no responsibility for either its use
or for infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use
in normal commercial applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements are
not recommended without additional processing by ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS does not authorize or warrant any ICS
product for use in life support devices or critical medical instruments.
rebmuNredrO/traPgnikraMegakcaPtnuoCerutarepmeT
YA2448SCIYA2448SCIPFQLdaeL23yartrep052C°58otC°0
TYA2448SCIYA2448S
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The aforementioned trademark, HiPerClockS™ is a trademark of Integrated Circuit Systems, Inc. or its subsidiaries in the United States and/or other countries.
8442AY www.icst.com/products/hiperclocks.html REV. C JULY 8, 2004
15
Integrated
Circuit
Systems, Inc.
ICS8442
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
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