1
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
SP3224E-SP3227E
FEATURES
■ 15kVESDprotectedRS-232I/Opins
■ AutoOn-line®Plusautomaticpowersavingmode
■ MeetstrueEIA/TIA-232-Fstandardsfrom+3.0Vto
+5.5Vpowersupply.
■ AdherestoEIA/TIA-562forinteroperabilitywith
EIA/TIA-232downtoa+2.7Vsupplyvoltage
■ Regulatedchargepumpyieldsstable
RS-232outputs
■ Drop-inreplacementtoMAX3224,ICL3224,
MAX3225,ICL3225,MAX3226,ICL3226,
MAX3227andICL3227
■ SP3224EandSP3226EreducedEMIwithaslew
ratecontrolled250kbpsdatarate
■ SP3225EandSP3227E-highspeeddatarateof
1Mbps.
■ AvailableinRoHScompliant,LeadFree
Packaging
3.0V to 5.5V RS-232 Transceivers with Auto On-Line® Plus
DESCRIPTION
TYPICAL APPLICATIONS
■ Diagnostic/Serialportson
embeddedapplications
■ HandheldTestEquipment
■ PCrelatedPeripheralsand
Equipment
■ BatteryPoweredEquipment
■ Point-of-saleEquipment
■ Set-topBox
TheSP3224E/3225Eare2-driver/2-receiverdevicesandtheSP3226E/SP3227Eare1-
driver/1-receiverdevices.Allareidealforcomputerperipherals,point-of-saleequipment,
consumer and embedded applications. These devices use an internal high-efciency,
charge-pump power supply that requires only 0.1μF capacitors in 3.3V operation. This
charge pump and Exar’s driver architecture allow it to deliver compliant RS-232 perfor-
mancefromasinglepowersupplyrangingfrom+3.0Vto+5.5V.Atvoltagesbetween2.7V
and3.0VthedriveroutputsarecompliantwithRS-562andcaninterfacetoRS-232over
shortcables.
TheAutoOn-line®Plusfeatureallowsthedevicetoautomatically“wake-up”duringashut-
downstateupondetectingactivityandtoenteralowpowershutdownifidle.Thispower
savingfeaturefunctionswithoutsysteminterventionormodicationstosoftwareordriv-
ers.
SELECTION TABLE
Alldevicesfeature3.0Vto5.5Vpowersupply,4smallchargepumpcapacitors,and15kVESD
protection.
Device DataRate(bps) No.of
Drivers/Receivers
READYpin Low-PowerShutdown Package
SP3224E 250k 2/2 Yes AutoOn-Line®Plus 20SSOP/TSSOP
SP3225E 1M 2/2 Yes AutoOn-Line®Plus 20SSOP/TSSOP
SP3226E 250k 1/1 Yes AutoOn-Line®Plus 16SSOP/TSSOP
SP3227E 1M 1/1 Yes AutoOn-Line®Plus 16SSOP/TSSOP
SP3224E
SP3225E
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
READY
C1+
V+
C1-
C2+
C2-
V-
T
2
OUT
R
2
IN
R
2
OUT
SHUTDOWN
V
CC
GND
T
1
OUT
R
1
IN
R
1
OUT
14
13
12
11
ONLINE
T
1
IN
T
2
IN
STATUS
2
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
ELECTRICAL SPECIFICATIONS
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.
ABSOLUTE MAXIMUM RATINGS
SupplyVoltage(Vcc).................................................-0.3Vto+6.0V
V+(Note1)................................................................-0.3Vto+7.0V
V-(Note1).................................................................+0.3Vto-7.0V
|V+|+|V-|.................................................................................+13V
InputvoltageatTTLinputpins............................-0.3VtoVcc+0.3V
RxIN.........................................................................................±16V
Driveroutput(fromGround)..................................................±13.2V
RxOUT,STATUS..................................................-0.3VtoVcc+0.3V
ShortCircuitDuration,TxOUTtoGND,.Continuous
(Oneoutputatatimemaximum)
StorageTemperature...............................................-65°Cto+150°C
OperatingTemperatureSP322XECX...........................0°Cto+70°C
OperatingTemperatureSP322XEEX........................-40°Cto+85°C
LeadTemperature(soldering,10s).......................................+300°C
Maximumjunctiontemperature.....................................................150°C
Thermal Derating, Junction to Ambient
SSOP20..............................................................................θJA =83°C/W
TSSOP20.......................................................................θJA =110.7°C/W
SSOP16..............................................................................θJA =87°C/W
TSSOP16.......................................................................θJA =100.4°C/W
Note1:V+andV-canhavemaximummagnitudesof7V,buttheir
absolutedifferencecannotexceed13V.
UnlessotherwisenotedVCC=+3.0Vto+5.5V,TAMB=TMINtoTMAX,.TypicalvaluesareatTAMB=+25°C.
C1–C4=0.1μFtestedat3.3V±10%.C1=0.047μFC2–C4=0.33μFtestedat5V±10%.
Parameters Symb Test Conditions Min. Typ. Max. Unit
DC Characteristics
SupplyCurrent,AutoOn-Line®Plus Icc3
Receiversidle,TxIN=VccorGND,
ONLINE=GND,SHUTDOWN =Vcc
Note 2
1 10 μA
SupplyCurrent,Shutdown Icc2SHUTDOWN=GND 1 10 μA
SupplyCurrent,Active Icc1ONLINE = SHUTDOWN=Vcc,NoLoad 1.5 3.0 mA
SupplyCurrent,Active Icc1ONLINE = SHUTDOWN=Vcc=3.3V,
NoLoad 0.7 2.0 mA
Driver Input and Logic Input Pins
LogicInput
Voltage
High
Vih Vcc=3.3V 2
V
Vih Vcc=5.0V 2.4
Low Vil 0.8
LogicThreshold Vt1.5
LogicInputLeakageCurrent Iil 0.05 ±1.0 μA
LogicInputHysteresis Vhys 100 mV
Receiver Outputs and STATUS Output
ReceiverOutputVoltageLow Vol Iout = -1.6mA 0.4 V
ReceiverOutputVoltageHigh Voh Iout = 1mA Vcc
- 0.6 V
Note2:Characterized,not100%tested.
3
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
ELECTRICAL SPECIFICATIONS
Parameters Symb Test Conditions Min. Typ. Max.
Driver Outputs
OutputVoltageSwing VoOutputload=3kΩtoGND ±5.0 ±6.0 V
Outputload=OpenCircuit ±15.0
ShortCircuitCurrent Vout=0V ±60 mA
Power-OffImpedance Vcc=V+=V-=0
transmitteroutputs=±2V
300 10M Ω
OutputLeakageCurrent Vcc=0or3Vto3.3V,Vout
=±12V,Driversdisabled
±25 μA
Receiver Inputs
InputVoltageRange -15 15 V
InputThresholdLow Vcc=3.3V 0.6 1.2 V
Vcc=5.0V 0.8 1.5
InputThresholdHigh Vcc=3.3V 1.5 2.4 V
Vcc=5.0V 1.8 2.4
InputHysteresis 500 mV
InputResistance 3 5 7 kΩ
ESD Protection
ESDProtectionforR_In,T_Outpins HumanBodyModel ±15 kV
AllOtherPins HumanBodyModel ±2 kV
Auto On-line® Plus (ONLINE = GND, SHUTDOWN = Vcc)
RxInputThresholdtoSTATUSoutputhigh ±2.7 V
RxInputThresholdtoSTATUSoutputlow ±0.3 V
ThresholdtoSTATUShigh tsth 0.5 μs
ThresholdtoSTATUSlow tstl 30 μs
RxorTxtransitiontodriversenabled tonline Note 3 100 μs
LastRxorTxtransitiontodriversdisabled toffline Note 2, 3 15 30 60 sec
Note3:Atransmitter/receiveredgeisdenedasatransitionthroughinputlogicthresholds.
UnlessotherwisenotedVCC=+3.0Vto+5.5V,TAMB=TMINtoTMAX,.TypicalvaluesareatTAMB=+25°C.
C1–C4=0.1μFtestedat3.3V±10%.C1=0.047μFC2–C4=0.33μFtestedat5V±10%.
4
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
TIMING CHARACTERISTICS
UnlessotherwisenotedVcc=+3.0Vto+5.5V,TAmb=TmintoTmAx,.TypicalvaluesareatTAmb=+25°C.C1–C4=
0.1μFtestedat3.3V±10%.C1=0.047μFC2–C4=0.33μFtestedat5V±10%
Parameters Symbol Test Conditions Min. Typ. Max. Unit
SP3224E and SP3226E
MaximumDataRate RL=3kΩ,CL=1000pF.One
transmitterswitching. 250 kbps
Transition-Region
SlewRate
Measurementtakenfrom
+3.0Vto-3.0Vor-3.0Vto+3.0V,
TAmb = 25°c
RL=3kΩto7kΩ,
CL = 150pF to 1000pF
4 30 V/μs
ReceiverPropagation
Delay tRPHL , tRPLH
R_INtoR_OUT,
CL = 150pF 0.22 µs
ReceiverOutput
EnableTime tRZH , tRZL RL=3kΩ,CL = 150pF 0.2 2 µs
ReceiverOutput
DisableTime tRHZ , tRLZ 0.2 2 µs
ReceiverSkew |tPHL - tPLH|at1.5V 200 ns
Parameters Symbol Test Conditions Min. Typ. Max. Unit
SP3225E and SP3227E
MaximumDataRate
RL=3kΩ,CL=250pF.One
transmitterSwitching 1000 kbps
RL=3kΩ,CL=1000pF.One
transmitterSwitching 500 kbps
InstantaneousSlew
Rate
Measurementtakenfrom+3.0V
to-3.0Vor-3.0Vto+3.0V,
TAmb=25°C 24 150 V/μs
RL=3kΩto7kΩ,
CL = 150pF to 250pF
DriverSkew |tDPHL - tDPLH|atzerocrossing 75 ns
ReceiverPropagation
Delay tRPHL , tRPLH R_INtoR_OUT,CL = 150pF 0.20 µs
ReceiverOutput
EnableTime tRZH , tRZL 0.3 2 µs
ReceiverOutput
DisableTime tRHZ , tRLZ 0.2 2 µs
ReceiverSkew |tPHL - tPLH|at1.5V 80 ns
5
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
0
5
10
15
20
25
30
35
40
45
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
Transmitter Output Slew Rate (V/us)
SRpos
SRneg
SRavg
TYPICAL PERFORMANCE CHARACTERISTICS:CURVES
SP3224E/SP3226ETransmitterInputto
ReceiverOutputPropagationDelayvs.
LoadCapacitance
0
0.5
1
1.5
2
2.5
0 1000 2000 3000 4000 5000
TxIn to RxOut Propagation Delay (us)
SP3224E/SP3226ETransmitterOutput
SlewRatevs.LoadCapacitance
0
5
10
15
20
25
30
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
Transmitter Output Slew Rate (V/us)
SRpos
SRneg
SRavg
SP3224E/SP3226ETransmitterOutput
Voltagevs.LoadCapacitance
-6
-4
-2
0
2
4
6
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
Transmitter Output Voltage (V)
V+
V-
SP3225E/SP3227ETransmitterInputto
ReceiverOutputPropagationDelayvs.
LoadCapacitance
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
TxIn to RxOut Propagation Delay (us)
SP3225E/SP3227ETransmitterOutput
SlewRatevs.LoadCapacitance
SP3225E/SP3227ETransmitterOutput
Voltage
-6
-4
-2
0
2
4
6
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
Trasmitter Output Voltage (V)
V+
V-
TxIntoRxOutPropagationDelay(us)
TxIntoRxOutPropagationDelay(us)
TransmitterOutputSlewRate(V/us)
TransmitterOutputSlewRate(V/us)
TransmitterOutputVoltage(V)
TransmitterOutputVoltage(V)
6
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
0
50
100
150
200
250
0 500 1000 1500 2000 2500 3000 3500
Load Capacitance (pF)
Transmitter Skew (ns)
SP3224, 250kbps
SP3225, 1Mbps
0
5
10
15
20
25
30
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
Supply Current (mA)
SP3225, 1Mbps
SP3227
SP3224, 250kbps
SP3226
DriverSkew
vs.LoadCapacitance
SupplyCurrent
vs.LoadCapacitance
TransmitterSkew(ns)
SupplyCurrent(mA)
Charge Pump Turn-on Time versus Temperature
50
55
60
65
70
75
80
85
-55 -30 -5 20 45 70 95
Temperature (C)
Charge Pump Turn-on Time (us)
ChargePumpTurn-OnTime
vs.Temperature
ChargePumpTurn-OnTime(us)
TYPICAL PERFORMANCE CHARACTERISTICS:CURVES
7
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
TYPICAL PERFORMANCE CHARACTERISTICS: SCOPE SHOTS
SP3224E/SP3226EWaveforms
for250kbpsClockRate,RL=3kΩ,
CL=1000pF
SP3224E/SP3226EWaveforms
for250kbpsClockRate,RL=3kΩ,
CL=4700pF
SP3224E/SP3226EChargePump
OutofShutdown
SP3224E/SP3226EChargePump
IntoShutdown
SP3224E/SP3226EChargePump
PowerOnTime,Vcc=3.3V
SP3224E/SP3226EChargePump
Waveformsfor250kbpClockRate
AllChargePumpwaveformsusechargepumpcapacitorvaluesC1-C4=0.1µF
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
SP3224E/SP3226EC2+Charge
PumpWaveforms,Vcc=3.3V,All
Channelsswitching
SP3224E/SP3226EC2+Charge
PumpWaveforms,Vcc=5V,
AllChannelsswitching
SP3225E/SP3227EWaveforms
for1MbpsClockRate,RL=3KΩ,
CL=50pF
SP3225E/SP3227EWaveformsfor
1MbpsClockRate,RL=3KΩ,
CL=250pF
SP3225E/SP3227EWaveforms
for1MbpsClockRate,RL=3KΩ,
CL=1000pF
SP3225E/SP3227ECharge
PumpOutofShutdown
TYPICAL PERFORMANCE CHARACTERISTICS: SCOPE SHOTS
AllChargePumpwaveformsusechargepumpcapacitorvaluesC1-C4=0.1µF
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
TYPICAL PERFORMANCE CHARACTERISTICS
SP3225E/SP3227EChargePump
IntoShutdown
SP3225E/SP3227EChargePump
PowerOnTime,Vcc=3.3V
SP3225E/SP3227EChargePump
Waveformsfor1MbpsClockRate
SP3225E/SP3227EChargePump
Waveforms,Vcc=3.3V,AllChan-
nelSwitching
SP3225E/SP3227EChargePump
Waveforms,Vcc=5V,AllChannel
Switching
AllChargePumpwaveformsusechargepumpcapacitorvaluesC1-C4=0.1µF
10
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Generator
(see note B) 50Ω
3V
SHUTDOWN
RS-232
Output
CL
(see note A)
RL
TEST CIRCUIT
Figure 1. Driver Slew Rate
SR= 6V
tTHL or tTLH
tTLHtTHL
3V
-3V
3V
-3V
3V
0V
VOH
VOL
Input
Output
VOLTAGE WAVEFORMS
A. CL includes probe and jig capacitance
B. The pulse generator has the following characteristics: PRR= 250kbit/s, Zo=50Ω, 50% duty cycle, tr ≤10ns, tf ≤10ns
NOTES
Generator
(see note B) 50Ω
3V
SHUTDOWN
RS-232
Output
CL
(see note A)
RL
TEST CIRCUIT
Figure 2. Driver Propagation and Skew
tDPLH
tDPHL
1.5V
50% 50%
3V
0V
VOH
VOL
Input
Output
VOLTAGE WAVEFORMS
1.5V
Skew= ItDPHL- tDPLHI
A. CL includes probe and jig capacitance
B. The pulse generator has the following characteristics: PRR= 250kbit/s, Zo=50Ω, 50% duty cycle, tr ≤10ns, tf ≤10ns
NOTES
CHARACTERIZATION CIRCUITS AND WAVEFORMS
Generator
(see note B) 50Ω
3V
SHUTDOWN
RS-232
Output
CL
(see note A)
TEST CIRCUIT
NOTES A. CL includes probe and jig capacitance
B. The pulse generator has the following characteristics: PRR= 250kbit/s, Zo=50Ω, 50% duty cycle, tr ≤10ns, tf ≤10ns
Figure 3. Receiver Propagation Delay and Skew
tRPLH
tRPHL
1.5V
50% 50%
3V
0V
VOH
VOL
Input
Output
VOLTAGE WAVEFORMS
1.5V
3V or 0V
ONLINE
Skew= ItRPHL- tRPLHI
3V or 0V
ONLINE
3V or 0V
SHUTDOWN
50Ω
Generator
(See Note B)
CL
(see note A)
Output
RL
GNDVCC
S1
TEST CIRCUIT
NOTES: A CL includes probe and jig capacitance
B. The pulse generator has the folowing characteristics Zo=50Ω, 50% duty cycle, tr ≤10ns, t f ≤10ns
C. tPLZ and tPHZ are the same as tdis
D. tPZL and tPZH are the same as ten
Figure 4. Receiver Enable and Disable Times
VOLTAGE WAVEFORMS
Input
tPHZ
1.5V 1.5V
3V
0V
VOH
50%
0.3V
(51 at GND)
Output
tPLZ
(51 at VCC)
Output
0.3V
50%
VOL
tPZL
(S1 at VCC)
tPZH
11
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THEORY OF OPERATION
Description
TheSP3224EandSP3225Eare2-driver/
2-receiver devices. The SP3226E and
SP3227E are 1-driver/1-receiver devices.
Allareidealforserialportsinembedded,
consumer, portable, or handheld applica-
tions.The transceiversmeettheEIA/TIA-
232 and ITU-T V.28/V.24 communication
protocolsforreliableserialcommunication.
ThedevicesfeatureExar’sproprietaryand
patented(U.S.5,306,954)on-boardcharge
pump circuitry that generates ±5.5V RS-
232voltagelevelsfroma single +3.0V to
+5.5Vpowersupply.
The SP3224E-SP3227E are ideal choic-
es for power sensitive designs. With the
AutoOn-line®Plusenabled,theSP3224E-
SP3227E reduce supply current to 1µA
whenever the transceivers are in idle. In
shutdown, the internal charge pump and
thedriverswillshutdown.Thisfeatureal-
lowsdesign engineers to address power
saving concerns without major design
changes.
Theory Of Operation
The SP3224E-SP3227E are made up of
fourbasiccircuitblocks:1.Drivers,2.Re-
ceivers, 3. the Exar proprietary charge
pump,and4.AutoOn-line®Pluscircuitry.
Drivers
The drivers are inverting level transmit-
tersthatconvertTTLorCMOSlogiclev-
els to 5.0V EIA/TIA-232 levels with an
inverted sense relative to the input logic
levels. Typically, the RS-232 output volt-
ageswingis+5.4Vwithnoloadand+5V
minimumfullyloaded.Thedriveroutputs
areprotectedagainstinniteshort-circuits
togroundwithoutdegradationinreliabili-
ty.ThesedriverscomplywiththeEIA-TIA-
232-Fand all previous RS-232 versions.
Unuseddriverinputsshouldbeconnected
toGNDorVCC.
The drivers can guarantee output data
ratesfullyloadedwith3KΩinparallelwith
1000pF (SP3224E/SP3226E), or 3KΩ in
parallel with 250pF (SP3225E/SP3227E)
ensuringcompatibilitywithPC-to-PCcom-
municationsoftware.Theslewrateofthe
driveroutputontheSP3224E/SP3226Eis
internallylimitedtoamaximumof30V/μs
in order to meet the EIA standards (EIA
RS-232D 2.1.7, Paragraph 5). The Slew
RateofSP3225E/SP3227Eisnotlimited
toenablehigherspeeddatatransfers.The
transitionoftheloadedoutputfromHIGH
toLOWalsomeetsthemonotonicsignal
transitionrequirementsofthestandard.
Receivers
The receivers convert EIA/TIA-232 signal
levels to TTL or CMOS logic output lev-
els.Receiversremainactiveduringdevice
shutdown. Since receiver input is usually
fromatransmissionlinewherelongcable
lengths and system interference can de-
gradethesignal,theinputshaveatypical
hysteresismarginof500mV.Thisensures
thatthereceiverisvirtuallyimmunetonoisy
transmissionlines.Shouldaninputbeleft
unconnected,aninternal5KΩpulldownre-
sistor to ground will commit the output of
thereceivertoaHIGHstate.
Charge Pump
Thechargepump is a Exar–patentedde-
sign (US Patent #5,306,954) and uses a
unique approach compared to older less-
efcient designs. The charge pump still
requiresfourexternalcapacitors,butuses
afourphasevoltage shiftingtechniqueto
attain symmetrical 5.5V power supplies.
The internal power supply consists of a
regulateddualchargepumpthatprovides
outputvoltages5.5Vregardlessofthein-
putvoltage(Vcc)overthe+3.0Vto+5.5V
range. This is important to maintain com-
pliant RS-232 levels regardless of power
supplyuctuations.
Thechargepumpoperatesinadiscontinu-
ousmodeusinganinternaloscillator.Ifthe
outputvoltagesarelessthanamagnitude
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THEORY OF OPERATION
of5.5V,thechargepumpisenabled.Ifthe
output voltages exceed a magnitude of
5.5V,thechargepumpisdisabled.Thisos-
cillatorcontrolsthefourphasesofthevolt-
age shifting.A description of each phase
follows.
Highly Efcient Charge Pump
Thechargepumpisusedtogenerateposi-
tive and negative signal voltages for the
RS-232drivers.Thisenablesfullycompli-
antRS-232andV.28signalsfromasingle
3.0or5.5Vpowersupply.
Thechargepumpsusefourexternalcapac-
itorstoholdandtransferelectricalcharge.
The Exar patented design (US Patent
#5,306,954)usesauniqueapproachcom-
pared to older less efcient designs. The
pumps use a four–phase voltage shifting
techniquetoattainsymmetricalV+andV-
powersupplies.Anintelligentcontroloscil-
latorregulatestheoperationofthecharge
pump to maintain the proper voltages at
maximumefciency.
Phase 1
Vss charge store and double: The posi-
tiveterminalsofcapacitorsC1andC2are
chargedfromVccwiththeirnegativetermi-
nals initially connected to ground. C1+ is
then connected to ground and the stored
charge from C1– is superimposed onto
C2–.SinceC2+ is stillconnectedtoVcc
thevoltagepotentialacrosscapacitorC2is
now2xVcc.
Phase 2
Vss transfer and invert: Phase two con-
nectsthenegativeterminalofC2totheVss
storagecapacitorandthepositiveterminal
ofC2toground.Thistransfersthedoubled
andinverted(V–)voltageontoC4.Mean-
while, capacitor C1 charged from Vcc to
prepareitforitsnextphase.
Phase 3
Vddchargestoreanddouble:Phasethree
is identical to the rst phase. The posi-
tiveterminalsofcapacitorsC1andC2are
chargedfromVccwiththeirnegativetermi-
nals initially connected to ground. C1+ is
then connected to ground and the stored
charge from C1– is superimposed onto
C2–. Since C2+ is still connected to Vcc
thevoltagepotentialacrosscapacitorC2is
now2xVcc.
Phase 4
Vdd transfer: The fourth phase connects
thenegativeterminalofC2togroundand
thepositiveterminalofC2totheVddstor-
age capacitor. This transfers the doubled
(V+)voltageonto C3. Meanwhile, capaci-
tor C1 charged from Vcc to prepare it for
itsnextphase.
TheExarchargepumpgeneratesV+and
V–independentlyfromVcc.Henceinano-
loadconditionV+andV-willbesymmetri-
cal. Older charge pump approaches gen-
erateV+andthen use part ofthatstored
chargetogenerateV-.Becauseofinherent
lossesthemagnitudeofV-willbesmaller
thanV+ontheseolderdesigns.
Under lightly loaded conditions the intelli-
gentpumposcillatormaximizes efciency
byrunningonlyasneededtomaintainV+
andV–.Sinceinterfacetransceiversoften
spendmuchoftheirtimeatidlethispower-
efcientinnovationcangreatlyreducetotal
power consumption. This improvement is
made possible by the independent phase
sequenceoftheExarchargepump
design.
The clock rate for the charge pump typi-
callyoperatesatgreaterthan70kHzallow-
ing the pump to run efciently with small
0.1μF capacitors. Efcient operation de-
pendsonrapidlycharginganddischarging
C1andC2,thereforecapacitorsshouldbe
mountedclosetotheICandhavelowESR
(equivalentseriesresistance).Inexpensive
surfacemountceramiccapacitors(suchas
13
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
THEORY OF OPERATION
TheSP3224E-SP3227Edeviceshavethe
advancedAutoOn-Line®Plusfeature
RS-232signalsusebothpositiveandneg-
ativevoltagesofgreaterthan±5Vmagni-
tude.Receivershavenominal5kΩimped-
ance to ground. Even when idle, drivers
willmaintainoutputsignalvoltagecreating
a continuous current ow. In low power,
batteryoperateddevicesthisconstantcur-
rentdraincandecreasebatterylife
signicantly.
are widely used for power-supply decou-
pling)areidealforuseonthechargepump.
Thechargepumpsaredesignedtobeable
to function properly with a wide range of
capacitorstylesandvalues.Ifpolarizedca-
pacitorsareusedthepositiveandnegative
terminals should be connected as shown
ontheTypicalOperatingCircuit.
Capacitance values may be increased if
operatingathigherVccortoprovidegreat-
erstabilityasthecapacitorsage.
Minimum Recommended Charge Pump Capacitor Values
InputVoltageVcc ChargePumpCapacitorValueforSP32XX
3.0Vto3.6V C1-C4=0.1µF
4.5Vto5.5V C1=0.047µF, C2-C4=0.33µF
3.0Vto5.5V C1-C4=0.22µF
ChargePumpCapacitorValues
C
2
+
-
V
CC
C
3
C
4
C
1
+ +
+
e
-
e
-
Phases 1 and 3: Store/Double.
Double charge from C 1 onto C2.
C 2 is now charged to -2xVcc
+
C
2
+
-
V
CC
C
3
C
4
C
1
+ +
+
e
-
+
e
+ e
+
C
2
+
-
V
CC
C
3
C
4
C
1
+ +
+
Phase 2 – Vss transfer from C2 to C4.
Meanwhile C 1 is charged to Vcc
e
-
e
-
e
-
+
Vss
transfer from C2 to C3.
Meanwhile C1 is charged to Vcc
V
DD
V-
V+
V-
V+
V+
Patented 5,306,954
Phase 4 VDD
ChargePumpPhases
14
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
thatsavespowerbyturningoffthecharge
pumpsanddriveroutputswhenthetrans-
ceiverinputsareidleformorethan30sec-
onds.Auto On-line® Plus is equivalent to
Maxim’s“AutoShutdownPlus”feature.It
differs from our existingAuto On-line® by
relying on signal transitions rather than
voltage levels to trigger shutdown and
wakeup.
AutoOn-Line®Plusautomaticallyputsthe
deviceintoastandbymodewhereitdraws
only1μAtypical.Whenthedevicedetects
activityoneitherthereceiverordriverin-
putsitwillautomaticallyawakeandactivate
to allow serial communication. Both the
wakeup and shutdown happen automati-
cally,withoutanyuserintervention,special
drivers,orsoftwaremodications.
Wakeup and shutdown can be exter-
nally controlled by the ONLINE and
SHUTDOWNpins.WhenONLINEisdriv-
en to logic LOW, the Auto On-line® Plus
functionisactive.DrivingSHUTDOWN to
+0.3V
R_IN
-0.3V
30µs
timer STATUS
INVALID ASSERTED IF ALL RECEIVER INPUTS ARE
BETWEEN +0.3V AND -0.3V FOR AT LEAST 30µS
T_IN
R_IN EDGE
DETECT
EDGE
DETECT SHUTDOWN
S
A
ONLINE
30s
timer
Figure 3a.STATUS Functional Diagram STATUS low Figure 3c. Auto On-line¨ Plus Logic
+2.7V
R_IN
-2.7V
30µs
timer STATUS
INVALID DEASSERTED IF ALL RECEIVER INPUTS ARE
BETWEEN +2.7V AND -2.7V FOR AT LEAST 30µS
Figure 3b. STATUS Functional Diagram, STATUS high.
SHUTDOWN
ONLINE
AUTO ONLINE
POWERDOWN
POWERDOWN IS ONLY A INTERNAL SIGNAL. IT
CONTROLS THE OPERATIONAL STATUS TO THE
TRANSMITTERS AND THE POWER SUPPLIES.
Figure 3d. Powerdown Logic
AUTO ONLINE
logicLOWforcesthedeviceintoshutdown
stateregardlessofinputactivityorthesta-
tusoftheONLINE pin.
TheSTATUSoutputdetermineswhethera
valid RS-232 signal voltage is present on
theinputs.TheSTATUSpingoestoalogic
LOWwhenthereceiverinputsignallevels
collapsenearreferenceground.Thismay
occur when the RS-232 cable is discon-
nected or the RS-232 drivers of the con-
nectedperipheralareturnedoff.
STATUSmaybeusedtoindicateDTRora
RingIndicatorsignalortodeterminewheth-
eraliveRS232driverorcableisconnect-
ed. By connecting the STATUS output to
ONLINEinput,theSP3224E-SP3227Ewill
shutdownwhen novalidsignallevel and
noinputtransitionsaredetected,andwake
uponavalidsignallevelorsignaledge.Ifit
detectsnosignaltransitionswiththepast30
seconds,thedevicewillgointolowpower
mode.ByconnectingtheSTATUSoutputto
boththeONLINEinputandSHUTDOWN
inputpins,thedeviceentersintoshutdown
whennotreceivingavalidRS-232signalvoltage
input.
WhentheSP3224E-SP3227Edevicesare
THEORY OF OPERATION
Receiver
5k
Ω
15
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AutoOn-Line(existing) Deviceenterslow-powermodeifreceiverinputsseelessthanvalid+/-3V.
STATUS(orINVALID)signaloutputindicatesifvalidsignalvoltageisat
receivers.
AutoOn-LinePlus(new) Deviceenterslow-powermodeifdriverinputsorreceiverinputsseeno
transitionsfor30seconds.Returntofullpowermodeuponanytransitionon
anydriverinputorreceiverinput
Shutdownoccursevenifdatacableisconnectedtoanactivedriver,aslong
asallinputsremainunchanged
STATUS(orINVALID)signalfunctionsasbefore.Indicatesifvalidsignal
voltageispresent.Buthasnoeffectonshutdown
ForSP3224EtheENinputisreplacedwithaREADYoutput.READYdrives
highwhenchargepumpachievesgreaterthan-4VVss(V-).Indicates“ready
totransmit.”
shutdown,thechargepumpsareturnedoff.
V+chargepumpoutputdecaystoVCC,the
V-outputdecaystoGND.Thedecaytime
willdependonthesizeofcapacitorsused
forthechargepump.Onceinshutdown,the
timerequiredtoexittheshutdownstateand
havevalidV+andV-levelsistypically50μs.
When the SP3224E-SP3227E drivers and
internalchargepumparedisabled,thesup-
plycurrentisreducedto1μA.
OperatingMode ONLINE SHDN |Rin| >
±2.7V
IdleInputs
(Rxin &
Txin)
Txout Rxout
ForcedShutdown X 0X X Hi-Z Active
ForcedOn-Line 1 1 X X Active Active
AutoOn-LinePlus
(Wakewhenactive)
0 1 X Active Active Active
AutoOnLinePlus
(Off-Linewhenidle)
0 1 X Idle>30s Hi-Z Active
AutoOn-LinePlus
(Wakeoncable)
STATUS 1Yes X Active Active
AutoOn-LinePlus
(Wakewhenactive)
STATUS 1 No Active Active Active
AutoOn-LinePlus
(Off-Linewhenidle)
STATUS 1 No Idle>30s Hi-Z Active
AutoOn-Line
(Wakeoncable)
STATUS STATUS Yes X Active Active
AutoOn-Line
(AutoShutoff)
STATUS STATUS No X Hi-Z Active
AutoOn-line®PlusTruthTable
THEORY OF OPERATION
ComparisonofAutoOn-line® Features
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THEORY OF OPERATION
RECEIVER
INPUTS
INVALID
REGION
}
TRANSMITTER
INPUTS
TRANSMITTER
OUTPUTS
STATUS
OUTPUT
OUTPUT
Vcc
0
Vcc
0
V+
Vcc
0
V-
t
TSTL
t
STH
t
OFFLINE
t
ONLINE
t
OFFLINE
t
ONLINE
AutoOn-Line® PlusTimingDiagram
tstl (=30µstyp.)
tsth (=0.4µstyp.)
toffline (=30styp.)
tonline (=100µstyp.)
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TYPICAL OPERATING CIRCUIT
SP3224E
2
4
6
5
3
7
15
GND
T1IN T1OUT
C1+
C1-
C2+
C2-
V+
V-
VCC
13
0.1µF
0.1µF
0.1µF
+
C2
C5
C1
+
+
C3
C4
+
+
0.1µF
0.1µF
17
RS-232
OUTPUTS
RS-232
INPUTS
LOGIC
INPUTS
VCC
18
5kΩ
R1IN
R1OUT
15 16
LOGIC
OUTPUTS
SP3225E
STATUS
SHUTDOWN VCC
READY
1
14
ONLINE 20
11
5kΩ
R2IN
R2OUT
10 9
T2IN T2OUT
12 8
SP3226E
2
4
6
5
3
7
15
GND
T1IN T1OUT
C1+
C1-
C2+
C2-
V+
V-
V
CC
11
0.1µF
0.1µF
0.1µF
+
C2
C5
C1
+
+
C3
C4
+
+
0.1µF
0.1µF
13 RS-232
OUTPUT
RS-232
INPUT
LOGIC
INPUT
V
CC
14
5kΩ
R1IN
R1OUT
98
LOGIC
OUTPUT
SP3227E
STATUS
SHUTDOWN V
CC
READY
1
12
ONLINE 16
10
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PINOUT DIAGRAMS
SP3224E
SP3225E
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
READY
C1+
V+
C1-
C2+
C2-
V-
T2OUT
R2IN
R2OUT
SHUTDOWN
VCC
GND
T1OUT
R1IN
R1OUT
14
13
12
11
ONLINE
T1IN
T2IN
STATUS
SP3226E
SP3227E
1
2
3
4
5
6
7
89
10
16
15
READY
C1+
V+
C1-
C2+
C2-
V-
R1IN
SHUTDOWN
VCC
GND
T1OUT
R1OUT
14
13
12
11
ONLINE
T1IN
STATUS
19
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20
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21
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
22
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
23
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3224E,3225E,3226E,3227E_101_081711
ORDERING INFORMATION
Part number Temperature range Package Type
SP3224ECA-L From 0°Cto+70°C LeadFree20pinSSOP
SP3224ECY-L From 0°Cto+70°C LeadFree20pinTSSOP
SP3224EEA-L From -40°Cto+85°C LeadFree20pinSSOP
SP3224EEY-L From -40°Cto+85°C LeadFree20pinTSSOP
SP3225ECA-L From 0°Cto+70°C LeadFree20pinSSOP
SP3225ECY-L From 0°Cto+70°C LeadFree20pinTSSOP
SP3225EEA-L From -40°Cto+85°C LeadFree20pinSSOP
SP3225EEY-L From -40°Cto+85°C LeadFree20pinTSSOP
SP3226ECA-L From 0°Cto+70°C LeadFree16pinSSOP
SP3226ECY-L From 0°Cto+70°C LeadFree16PINSSOP
SP3226EEA-L From -40°Cto+85°C LeadFree16pinSSOP
SP3226EEY-L From -40°Cto+85°C LeadFree16PINTSSOP
SP3227ECA-L From 0°Cto+70°C LeadFree16PINSSOP
SP3227ECY-L From 0°Cto+70°C LeadFree16PINTSSOP
SP3227EEA-L From -40°Cto+85°C LeadFree16PINSSOP
SP3227EEY-L From -40°Cto+85°C LeadFree16PINTSSOP
AvailableinTapeonReel
Notice
EXARCorporationreservestherighttomakechangestoanyproductscontainedinthispublicationinordertoimprovedesign,performanceorreliabil-
ity.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2011EXARCorporation
DatasheetAugust2011
Sendyourserialtransceivertechnicalinquirywithtechnicaldetailsto:serialtechsupport@exar.com
Reproduction,inpartorwhole,withoutthepriorwrittenconsentofEXARCorporationisprohibited.
DATE REVISION DESCRIPTION
11-20-06 P LegacySipexDatasheet
12-14-09 1.0.0 UpdatetoExarFormat.Changerevisionto1.0.0.ChangeSupplyCurrentActive
overfullVccrangemaximumfrom2.0mAto3.0mA.ChangeSupplyCurrentActive
atVcc=3.3Vmaximumfrom1.0mAto2.0mA.ChangeRXinputvoltageABSMaxi-
mumRatingfrom+/-18Vto+/-16V.
08-17-11 1.0.1 CorrecttypeerroronfrontpageFeatureslist.