1
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
■ +5VOnly
■ LowPowerBiCMOS
■ Driver/ReceiverEnableforMulti-Drop
congurations
■ LowPowerShutdownMode
(SP1481E)
■ EnhancedESDSpecications:
DESCRIPTION
The SP1481E and the SP1485E are a family of half-duplex transceivers that meet the
specicationsofRS-485andRS-422serialprotocolswithenhancedESDperformance.The
ESDtolerancehasbeenimprovedonthesedevicestoover+15KVforbothHumanBody
Model and IEC1000-4-2Air Discharge Method. These devices are pin-to-pin compatible
withExar'sSP481andSP485devicesaswellaspopularindustrystandards.Aswiththe
originalversions,theSP1481EandtheSP1485EfeatureExar'sBiCMOSdesignallowing
lowpoweroperationwithoutsacricingperformance.TheSP1481EandSP1485Emeetthe
requirementsoftheRS-485andRS-422protocolsupto20Mbpsunderload.TheSP1481E
isequippedwithalowpowerShutdownmode.
+15KVHumanBodyModel
+15KVIEC1000-4-2AirDischarge
+8KVIEC1000-4-2ContactDischarge
NowAvailableinLeadFreePackaging
SP1481E/SP1485E
Enhanced Low Power Half-Duplex
RS-485 Transceivers
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
2
ABSOLUTE MAXIMUM RATINGS
Thesearestressratingsonlyandfunctionaloperationofthedeviceat
theseratingsoranyotherabovethoseindicatedintheoperationsections
ofthespecicationsbelowisnotimplied.Exposuretoabsolutemaximum
ratingconditionsforextendedperiodsoftimemayaffectreliability.
VCC..............................................................................+7V
InputVoltages
Logic...................................................-0.3Vto(VCC+0.5V)
Drivers................................................-0.3Vto(VCC+0.5V)
Receivers.................................................................±15V
ELECTRICAL CHARACTERISTICS
TMINto TMAXandVCC=5V±5%unlessotherwisenoted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP1481E/SP1485E DRIVER
DC Characteristics
DifferentialOutputVoltage 3.5 VCC Volts Unloaded;R=∞;seeFigure1
DifferentialOutputVoltage 2 VCC Volts withload;R=50Ω;(RS-422);
seeFigure1
DifferentialOutputVoltage 1.5 VCC Volts withload;R=27Ω;(RS-485);seeFigure1
ChangeinMagnitudeofDriver
DifferentialOutputVoltagefor
ComplimentaryStates 0.2 Volts R=27ΩorR=50Ω;seeFigure1
DriverCommon-Mode
OutputVoltage 3 Volts R=27ΩorR=50Ω;seeFigure1
InputHighVoltage 2.0 Volts AppliestoDE,DI,RE
InputLowVoltage 0.8 Volts AppliestoDE,DI,RE
InputCurrent ±10 μA AppliestoDE,DI,RE
DriverShort-CircuitCurrent
VOUT=HIGH ±250 mA -7V≤VO≤+12V
VOUT=LOW
±250 mA -7V≤VO≤+12V
SP1481E/SP1485E DRIVER
AC Characteristics
MaximumDataRate 20 Mbps RE=5V,DE=5V;RDIFF=54Ω,
CL1 = CL2 = 100pF
DriverInputtoOutput 20 30 ns tPLH;RDIFF=54Ω,CL1 = CL2=100pF;
seeFigures3and5
DriverInputtoOutput 20 40 ns tPLH;RDIFF=54Ω,CLI= CL2=100pF;
(SP1485EMNONLY) SeeFigures3and5
DriverInputtoOutput 20 30 ns tPHL;RDIFF=54Ω,CL1 = CL2=100pF;
seeFigures3and5
DriverInputtoOutput 20 40 ns tPHL;RDIFF=54Ω,CL1 = CL2=100pF;
(SP1485EMNONLY) seeFigures3and5
DriverSkew 3 5 ns seeFigures3and5,
tSKEW = | tPLH - tPHL |
DriverRiseorFallTime 8 20 ns From10%to90%;RDIFF=54Ω,
CL1 = CL2=100pF;s
eeFigures3&
6
DriverEnabletoOutputHigh 40 70 ns CL=100pF;seeFigures4&6;S2closed
DriverEnabletoOutputLow 40 70 ns CL=100pF;seeFigures4&6;S1closed
DriverDisableTimefromLow 40 70 ns CL=100pF;seeFigures4&6;S1closed
DriverDisableTimefromHigh 40 70 ns CL=100pF;seeFigures4&6;S2 closed
OutputVoltages
Logic.............................................-0.3Vto(VCC+0.5V)
Drivers................................................................±15V
Receivers......................................-0.3Vto(VCC+0.5V)
StorageTemperature.....................................................-65˚Cto+150˚C
PowerDissipationperPackage
8-pinNSOIC(derate6.60mW/oCabove+70oC).........................550mW
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
SPECIFICATIONS (continued)
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP1481E/SP148
5E RECEIVER
DC Characteristics
DifferentialInputThreshold -0.2 +0.2 Volts -7V≤VCM≤+12V
DifferentialInputThreshold -0.4 +0.4 Volts -7V≤VCM≤+12V
(SP1485EMNONLY)
InputHysteresis 20 mV VCM=0V
OutputVoltageHigh 3.5 Volts IO=-4mA,VID=+200mV
OutputVoltageLow 0.4 Volts IO=+4mA,VID=-200mV
Three-State(HighImpedance)
OutputCurrent ±1 µA 0.4V≤VO≤2.4V;RE=5V
InputResistance 12 15 kΩ -7V≤VCM≤+12V
InputCurrent(A,B);VIN=12V +1.0 mA DE=0V,VCC=0Vor5.25V,VIN=12V
InputCurrent(A,B);VIN=-7V -0.8 mA DE=0V,VCC=0Vor5.25V,VIN=-7V
Short-CircuitCurrent7 95 mA 0V≤VO≤VCC
SP1481E/SP1485E RECEIVER
AC Characteristics
MaximumDataRate 20 Mbps RE=0V,DE=0V
ReceiverInputtoOutput 25 70 ns tPLH;RDIFF=54Ω,
CL1 = CL2
= 100pF;Figures3&7
ReceiverInputtoOutput 25 70 ns tPHL;RDIFF=54Ω,
CL1 = CL2
= 100pF;Figures3&7
Diff.ReceiverSkewItPLH-tPHLI 5 10 ns RDIFF=54Ω;CL1= CL2=100pF;
Figures3&7
ReceiverEnableto
OutputLow 45 70 ns CRL=15pF;Figures2&8;S1closed
ReceiverEnableto
OutputHigh 45 70 ns CRL=15pF;Figures2&8;S2closed
ReceiverDisablefromLow 45 70 ns CRL=15pF;Figures2&8;S1closed
ReceiverDisablefromHigh45 70 ns CRL=15pF;Figures2&8;S2closed
SP1481E
Shutdown Timing
TimetoShutdown 50 200 600 ns RE=5V,DE=0V
DriverEnablefromShutdown
toOutputHigh 40 100 ns CL=100pF;SeeFigures4&6;S2closed
DriverEnablefromShutdown
toOutputLow 40 100 ns CL=100pF;SeeFigures4&6;S1closed
ReceiverEnablefrom
ShutdowntoOutputHigh 300 1000 ns CL=15pF;SeeFigures2&8;S2closed
ReceiverEnablefrom
ShutdowntoOutputLow 300 1000 ns CL=15pF;SeeFigures2&8;S1closed
POWER REQUIREMENTS
SupplyVoltage +4.75 +5.25 Volts
SupplyCurrent
SP1481E/1485E
NoLoad 900 μA RE,DI=0VorVCC;DE=VCC
600 μA RE=0V,DI=0Vor5V;DE=0V
SP1481E
ShutdownMode 10 μA DE=0V,RE=VCC
ENVIRONMENTAL AND MECHANICAL
OperatingTemperature
Commercial(_C_) 0 +70 °C
Industrial(_E_) -40 +85 °C
(_M_) -40 +125 °C
StorageTemperature -65 +150 °C
Package
NSOIC(_N)
TMINto TMAXandVCC=5V±5%unlessotherwisenoted
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
4
PIN FUNCTION
Pin1–RO–ReceiverOutput.
Pin2–RE–ReceiverOutputEnableActiveLOW.
Pin3–DE–DriverOutputEnableActiveHIGH.
Pin4–DI–DriverInput.
Pin5–GND–GroundConnection.
Pin6–A–DriverOutput/ReceiverInputNon-inverting.
Pin7–B–DriverOutput/ReceiverInputInverting.
Pin8–Vcc–PositiveSupply4.75V<Vcc<5.25V.
SP1481E and SP1485E
Pinout(TopView)
Figure5.DriverPropagationDelays
+3V
0V
DI
A
B
DRIVER
OUTPUT
V
O
+
DIFFERENTIAL
OUTPUT
V
A
– V
B
0V
V
O
–
1.5V 1.5V
t
PLH
t
F
t
R
f ≥ 1MHz; t
R
≤ 1ns; t
F
≤ 1ns
V
O
1/2V
O
1/2V
O
t
PHL
Figure1.RS-485DriverDCTestLoadCircuit
Figure3.RS-485Driver/ReceiverTimingTestCircuit
CL1
15pF
RO
A
B
A
B
DI
CL2
RDIFF
500
CL
Output
Under
Test
S1
S2
VCC
1kΩ
1kΩC
RL
Receiver
Output S
1
S
2
Test Point
V
CC
Figure2.ReceiverTimingTestLoadCircuit
Figure4.RS-485DriverTimingTestLoad#2Circuit
A
B
R
R
VOD
VOC
5
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
INPUTS OUTPUTS
LINE
RE DE DI CONDITION B A
X 1 1 NoFault 0 1
X 1 0 NoFault 1 0
X 0 X X Z Z
X 1 X Fault Z Z
INPUTS OUTPUTS
RE DE A-B R
0 0 +0.2V 1
0 0 -0.2V 0
0 0 InputsOpen 1
1 0 X Z
Table1.TransmitFunctionTruthTable
Table2.ReceiveFunctionTruthTable
+3V
0V
DE
5V
V
OL
A
, B
0V
1.5V 1.5V
t
ZL
t
ZH
f = 1MHz; t
R
< 1ns ; t
F
< 1ns
V
OH
A
, B 2.3V
2.3V
t
LZ
t
HZ
0.5V
0.5V
Output normally LOW
Output normally HIGH
+3V
0V
5V
0V
1.5V 1.5V
tZL
tZH
f = 1MHz; tR≤ 1ns; tF ≤ 1ns
R1.5V
1.5V
tLZ
tHZ
0.5V
0.5V
Output normally LOW
Output normally HIGH
VIL
VIH
R
RE
Figure8.ReceiverEnableandDisableTimes
Figure7.ReceiverPropagationDelays
Figure6.DriverEnableandDisableTimes
A
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
6
AlogicLOWonRE(pin2)willenablethe
receiver,alogicHIGHonRE(pin2)willdis-
ablethereceiver.
ThereceiverfortheSP1481EandSP1485E
willoperateuptoatleast20Mbps.Thereceiver
foreachofthetwodevicesisequippedwiththe
fail-safefeature.Fail-safeguaranteesthatthe
receiveroutputwillbeinaHIGHstatewhen
theinputisleftunconnected.
Shutdown Mode
SP1481E
TheSP1481EisequippedwithaShutdown
mode.ToenabletheShutdownstate,both
the driver and receiver must be disabled
simultaneously.
AlogicLOWonDE(pin3)andalogicHIGH
onRE(pin2)willputtheSP1481EintoShut-
downmode.InShutdown,supplycurrentwill
droptotypically1μA.
ESD TOLERANCE
The SP1481E Family incorporates rug-
gedizedESDcellsonalldriveroutputand
receiver input pins. The ESD structure is
improvedoverourpreviousfamilyformore
rugged applications and environments
sensitive to electro-static discharges and
associatedtransients.TheimprovedESD
toleranceisatleast±15kVwithoutdamage
norlatch-up.
TherearedifferentmethodsofESDtesting
applied:
a)MIL-STD-883,Method3015.7
b)IEC1000-4-2Air-Discharge
c)IEC1000-4-2DirectContact
The Human Body Model has been the
generally accepted ESD testing method
for semiconductors. This method is also
specied in MIL-STD-883, Method 3015.7
for ESD testing. The premise of this ESD
testistosimulatethehumanbody’spotential
tostoreelectro-staticenergyanddischarge
ittoanintegratedcircuit.Thesimulationis
performedbyusingatestmodelasshown
inFigure7.ThismethodwilltesttheIC’s
capabilitytowithstandanESDtransientdur-
ingnormalhandlingsuchasinmanufactur-
ingareaswheretheICstendtobehandled
frequently.
DESCRIPTION
TheSP1481EandSP1485Earehalf-duplex
differentialtransceiversthatmeettherequire-
mentsofRS-485andRS-422.Fabricated
with a Exar proprietary BiCMOS process,
theseproductsrequireafractionofthepower
ofolderbipolardesigns.
TheRS-485standardisidealformulti-drop
applicationsandforlong-distanceinterfaces.
RS-485allowsupto32driversand32receiv-
erstobeconnectedtoadatabus,makingit
anidealchoiceformulti-dropapplications.
Sincethecablingcanbeaslongas4,000
feet,RS-485transceiversareequippedwith
awide(-7Vto+12V)commonmoderange
to accommodate ground potential differ-
ences. Because RS-485 is a differential
interface,dataisvirtuallyimmunetonoise
inthetransmissionline.
Drivers
The driver outputs of the SP1481E and
SP1485Earedifferentialoutputsmeetingthe
RS-485andRS-422standards.Thetypical
voltageoutputswingwithnoloadwillbe0
Voltsto+5Volts.Withworstcaseloading
of54Ωacrossthedifferentialoutputs,the
driverscanmaintaingreaterthan1.5Vvolt-
agelevels.ThedriversoftheSP1481E,and
SP1485Ehaveanenablecontrollinewhich
isactiveHIGH.AlogicHIGHonDE(pin3)
willenablethedifferentialdriveroutputs.A
logic LOW on DE (pin 3) will tri-state the
driveroutputs.
The transmitters of the SP1481E and
SP1485E will operate up to at least
20Mbps.
Receivers
TheSP1481EandSP1485Ereceivershave
differential inputs with an input sensitivity
aslowas±200mV.Inputimpedanceofthe
receiversistypically15kΩ(12kΩminimum).
Awidecommonmoderangeof-7Vto+12V
allowsforlargegroundpotentialdifferences
between systems. The receivers of the
SP1481E and SP1485E have a tri-state
enablecontrolpin.
7
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
The IEC-1000-4-2, formerly IEC801-2, is
generallyusedfortestingESDonequipment
andsystems.Forsystem manufacturers,
theymustguaranteeacertainamountofESD
protectionsincethesystemitselfisexposed
totheoutsideenvironmentandhumanpres-
ence.ThepremisewithIEC1000-4-2isthat
thesystemisrequiredtowithstandanamount
ofstaticelectricitywhenESDisappliedto
pointsandsurfacesoftheequipmentthat
areaccessibletopersonnelduringnormal
usage.The transceiver IC receives most
oftheESDcurrent when the ESD source
isappliedtotheconnectorpins.Thetest
circuitforIEC1000-4-2isshownonFigure8.
TherearetwomethodswithinIEC1000-4-2,
theAirDischargemethodandtheContact
Dischargemethod.
Figure7.ESDTestCircuitforHumanBodyModel
Figure8.ESDTestCircuitforIEC1000-4-2
R
C
C
S
R
S
SW1 SW2
R
C
Device
Under
Test
DC Power
Source
C
S
R
S
SW1 SW2
R
S
and
R
V
add up to 330W for IEC1000-4-2.
R
S
and
R
V
add up to 330W for IEC1000-4-2.
Contact-Discharge Module
R
V
R
C
C
S
R
S
SW1 SW2
R
C
Device
Under
Test
DC Power
Source
C
S
R
S
SW1 SW2
R
V
Contact-Discharge Module
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
8
With the Air Discharge Method, an ESD
voltageisappliedtotheequipmentunder
test(EUT)throughair.This simulatesan
electricallychargedpersonreadytoconnect
acableontotherearofthesystemonlyto
ndanunpleasantzapjustbeforetheperson
touchesthebackpanel.Thehighenergy
potentialonthepersondischargesthrough
anarcingpathtotherearpanelofthesystem
beforeheorsheeventouchesthesystem.
Thisenergy,whetherdischargeddirectlyor
throughair,ispredominantlyafunctionofthe
dischargecurrentratherthanthedischarge
voltage.Variableswithanairdischargesuch
asapproachspeedoftheobjectcarryingthe
ESDpotential tothesystemandhumidity
willtendtochange the dischargecurrent.
Forexample,therisetimeofthedischarge
currentvarieswiththeapproachspeed.
TheContactDischargeMethodappliesthe
ESDcurrentdirectlytotheEUT.Thismethod
wasdevisedtoreducetheunpredictability
oftheESDarc.Thedischargecurrentrise
timeisconstantsincetheenergyisdirectly
transferredwithouttheair-gaparc.Insitu-
ationssuchashandheldsystems,theESD
charge can be directly discharged to the
equipment from a person already holding
theequipment.Thecurrentistransferred
on to the keypad or the serial port of the
equipmentdirectlyandthentravelsthrough
thePCBandnallytotheIC.
ThecircuitmodelinFigures7and8represent
thetypicalESD testing circuitusedforall
threemethods.TheCSisinitiallycharged
with the DC power supply when the rst
switch(SW1)ison.Nowthatthecapacitor
ischarged,thesecondswitch(SW2)ison
whileSW1switchesoff.Thevoltagestored
inthecapacitoristhenappliedthroughRS,
thecurrentlimitingresistor,ontothedevice
undertest(DUT).InESDtests,theSW2
switch is pulsed so that the device under
testreceivesadurationofvoltage.
For the Human Body Model, the current
limitingresistor(RS)andthesourcecapacitor
(CS)are1.5kΩan100pF,respectively.For
IEC-1000-4-2, the current limiting resistor
(RS)andthesourcecapacitor(CS)are330Ω
an150pF,respectively.
ThehigherCSvalueandlowerRSvaluein
theIEC1000-4-2modelaremorestringent
thanthe HumanBody Model. The larger
storage capacitor injects a higher voltage
tothetestpointwhenSW2isswitchedon.
Thelowercurrentlimitingresistorincreases
thecurrentchargeontothetestpoint.
Figure9.ESDTestWaveformforIEC1000-4-2
t=0ns t=30ns
0A
15A
30A
t
HUMAN BODY IEC1000-4-2
MODEL Air Discharge Direct Contact Level
DriverOutputs ±15kV ±15kV ±8kV 4
ReceiverInputs ±15kV ±15kV±8kV 4
SP1481E,
SP1485E
FAMILY
9
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP1481E-1485E_102_102710
10
ORDERING INFORMATION
Model Temperature Range Package
SP1481ECN-L ................................................... 0˚Cto+70˚C ............................................... 8-pinNarrowSOIC
SP1481ECN-L/TR ..............................................0˚Cto+70˚C ............................................... 8-pinNarrowSOIC
SP1481EEN-L ................................................. .-40˚Cto+85˚C ............................................. 8-pinNarrowSOIC
SP1481EEN-L/TR ........................................... .-40˚Cto+85˚C ............................................. 8-pinNarrowSOIC
SP1485ECN-L ................................................... 0˚Cto+70˚C ............................................... 8-pinNarrowSOIC
SP1485ECN-L/TR ............................................. 0˚Cto+70˚C ............................................... 8-pinNarrowSOIC
SP1485EEN-L ..................................................-40˚Cto+85˚C.............................................. 8-pinNarrowSOIC
SP1485EEN-L/TR ............................................-40˚Cto+85˚C.............................................. 8-pinNarrowSOIC
SP1485EMN-L ................................................-40˚Cto+125˚C............................................. 8-pinNarrowSOIC
SP1485EMN-L/TR...........................................-40˚Cto+125˚C............................................. 8-pinNarrowSOIC
Notice
EXARCorporationreservestherighttomakechangestoanyproductscontainedinthispublicationinordertoimprovedesign,performanceorreli-
ability.EXARCorporationassumesnorepresentationthatthecircuitsarefreeofpatentinfringement.Chartsandschedulescontainedhereinare
onlyforillustrationpurposesandmayvarydependinguponauser'sspecicapplication.Whiletheinformationinthispublicationhasbeencarefully
checked;noresponsibility,however,isassumedforinaccuracies.
EXARCorporationdoesnotrecommendtheuseofanyofitsproductsinlifesupportapplicationswherethefailureormalfunctionoftheproductcan
reasonablybeexpectedtocausefailureofthelifesupportsystemortosignicantlyaffectitssafetyoreffectiveness.Productsarenotauthorizedfor
useinsuchapplicationsunlessEXARCorporationreceives,inwritting,assurancestoitssatisfactionthat:(a)theriskofinjuryordamagehasbeen
minimized;(b)theuserassumesallsuchrisks;(c)potentialliabilityofEXARCorporationisadequatelyprotectedunderthecircumstances.
Copyright2010EXARCorporation
DatasheetOctober2010
FortechnicalsupportpleaseemailExar'sSerialTechnicalSupportgroupat:serialtechsupport@exar.com
Reproduction,inpartorwhole,withoutthepriorwrittenconsentofEXARCorporationisprohibited.
DATE REVISION DESCRIPTION
03/08/07 JLegacySipexDatasheet
06/16/09 1.0.0 ConverttoExarformat,updateorderinginformationand
changerevisionto1.0.0
08/03/10 1.0.1 RemoveSP1485EMNoption.
10/27/10 1.0.2 ReactiviateSP1485EMNoptionperPCN#07-0502-01