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from a +3.0V to +5.5V power supply Interoperable with EIA/TIA-232 and
adheres to EIA/TIA-562 down to a +2.7Vpower source
AUTO ON-LINE® circuitry automaticallywakes up from a µA shutdown
Minimum 250Kbps data rate under load(EB)
Mbps data rate for high speed RS-232(EU)
Regulated Charge Pump Yields StableRS-232 Outputs Regardless of VCCVariations
ESD Specifications: +5KV Human Body Model +5KV IEC000-4-2 Air Discharge +8KV IEC000-4-2 Contact Discharge
DESCRIPTION
SELECTION TABLE
Applicable U.S. Patents - 5,306,954; and other patents pending.
®
Now Available in Lead Free Packaging
V-
1
2
3
4 17
18
19
20
5
6
7
16
15
14
SHUTDOWN
C1+
V+
C1-
C2+
C2-
ONLINE
EN
R1IN
GND
VCC
T1OUT
STATUS
8
9
10 11
12
13
R2IN
R2OUT
SP3223
T2OUT T1IN
T2IN
R1OUT
The SP3223 products are RS-232 transceiver solutions intended for portable applicationssuch as notebook and hand held computers. The SP3223 use an internal high-efficiency,charge-pump power supply that requires only 0.µF capacitors in 3.3V operation. This chargepump and Sipex's driver architecture allow the SP3223 series to deliver compliant RS-232performance from a single power supply ranging from +3.3V to +5.0V. The SP3223 is a 2-driver/2-receiver device ideal for laptop/notebook computer and PDA applications.
The AUTO ON-LINE® feature allows the device to automatically "wake-up" during a shutdownstate when an RS-232 cable is connected and a connected peripheral is turned on. Otherwise,the device automatically shuts itself down drawing less than µA.
ABSOLUTE MAXIMUM RATINGSThese are stress ratings only and functional operationof the device at these ratings or any other above thoseindicated in the operation sections of the specificationsbelow is not implied. Exposure to absolute maximumrating conditions for extended periods of time mayaffect reliability and cause permanent damage to thedevice.VCC.......................................................-0.3V to +6.0VV+ (NOTE 1).......................................-0.3V to +7.0VV- (NOTE 1)........................................+0.3V to -7.0VV+ + |V-| (NOTE 1)...........................................+13VICC (DC VCC or GND current).........................+100mAInput VoltagesTxIN, ONLINE,SHUTDOWN, EN (SP3223)..........-0.3V to VCC + 0.3VRxIN...................................................................+15V
Output VoltagesTxOUT.............................................................+13.2VRxOUT, STATUS.......................-0.3V to (VCC + 0.3V)Short-Circuit DurationTxOUT.....................................................ContinuousStorage Temperature......................-65°C to +150°C
The SP3223 is a 2-driver/2-receiver deviceideal for portable or handheld applications.The SP3223 transceivers meet the EIA/TIA-232and ITU-T V.28/V.24 communication protocolsand can be implemented in battery-powered,portable, or handheld applications such as note-book or handheld computers. The SP3223 de-vices feature Sipex's proprietary and patented(U.S.-- 5,306,954) on-board charge pump cir-cuitry that generates ±5.5V RS-232 voltage lev-els from a single +3.0V to +5.5V power supply.The SP3223 devices operate at this typical datarate when fully loaded.
The SP3223 series is an ideal choice for powersensitive designs. Featuring AUTO ON-LINE®
circuitry, the SP3223 reduces the power supplydrain to a 1µA supply current. In many portableor handheld applications, an RS-232 cable canbe disconnected or a connected peripheral can beturned off. Under these conditions, the internalcharge pump and the drivers will be shut down.
Otherwise, the system automatically comesonline. This feature allows design engineers toaddress power saving concerns without majordesign changes.
THEORY OF OPERATION
The SP3223 series is made up of four basiccircuit blocks:1. Drivers, 2. Receivers, 3. the Sipex proprietarycharge pump, and 4. AUTO ON-LINE® cir-cuitry.
Drivers
The drivers are inverting level transmitters thatconvert TTL or CMOS logic levels to 5.0V EIA/TIA-232 levels with an inverted sense relative tothe input logic levels. Typically, the RS-232output voltage swing is +5.4V with no load and+5V minimum fully loaded. The driver outputsare protected against infinite short-circuits toground without degradation in reliability. Thesedrivers comply with the EIA-TIA-232F and allprevious RS-232 versions. Unused driver inputsshould be connected to GND or V
CC.
The drivers can guarantee output data rates fullyloaded with 3KΩ in parallel with 1000pF,(SP3223EU, C
L= 250pF) ensuring compatibility
with PC-to-PC communication software.
The slew rate of the driver output on the E and EBversions is internally limited to a maximum of30V/µs in order to meet the EIA standards (EIARS-232D 2.1.7, Paragraph 5). The Slew Rate ofH and U versions is not limited to enable higherspeed data tranfers. The transition of the loadedoutput from HIGH to LOW also meets the mono-tonicity requirements of the standard.
Figure 12 shows a loopback test circuit used totest the RS-232 Drivers. Figure 13 shows the testresults where one driver was active at 235Kbpsand all drivers are loaded with an RS-232 re-ceiver in parallel with a 1000pF capacitor. RS-232 data transmission rate of 120Kbps to 1Mbps.provide compatibility with designs in personalcomputer peripherals and LAN applications.
Figure 13. Interface Circuitry Controlled by Micropro-cessor Supervisory Circuit
The receivers convert ±5.0V EIA/TIA-232levels to TTL or CMOS logic output levels.Receivers have an inverting output that can bedisabled by using the EN pin.
Receivers are active when the AUTO ON-LINE®
circuitry is enabled or when in shutdown.During the shutdown, the receivers will continueto be active. If there is no activity present at thereceivers for a period longer than 100µs or whenSHUTDOWN is enabled, the device goes into astandby mode where the circuit draws 1µA.Driving EN to a logic HIGH forces the outputs ofthe receivers into high-impedance. The truthtable logic of the SP3223 driver and receiveroutputs can be found in Table 2.
Since receiver input is usually from a transmis-sion line where long cable lengths and systeminterference can degrade the signal, the inputshave a typical hysteresis margin of 300mV. Thisensures that the receiver is virtually immune tonoisy transmission lines. Should an input be leftunconnected, an internal 5KΩ pulldown resistorto ground will commit the output of the receiverto a HIGH state.
Table 2. SHUTDOWN and EN Truth TablesNote: In AUTO ON-LINE® Mode where ONLINE =GND and SHUTDOWN = VCC, the device will shut downif there is no activity present at the Receiver inputs.
Figure 14. Loopback Test Circuit for RS-232 DriverData Transmission Rates
Charge Pump
The charge pump is a Sipex–patented design(U.S. 5,306,954) and uses a unique approachcompared to older less–efficient designs. Thecharge pump still requires four externalcapacitors, but uses a four–phase voltageshifting technique to attain symmetrical 5.5Vpower supplies. The internal power supply
Figure 15. Loopback Test Circuit result at 235Kbps(All Drivers Fully Loaded)
consists of a regulated dual charge pump thatprovides output voltages 5.5V regardless of theinput voltage (VCC) over the +3.0V to +5.5Vrange. This is important to maintain compliantRS-232 levels regardless of power supplyfluctuations.
The charge pump operates in a discontinuousmode using an internal oscillator. If the outputvoltages are less than a magnitude of 5.5V, thecharge pump is enabled. If the output voltagesexceed a magnitude of 5.5V, the charge pump isdisabled. This oscillator controls the four phasesof the voltage shifting. A description of eachphase follows.
Phase 1— VSS charge storage — During this phase ofthe clock cycle, the positive side of capacitorsC1 and C2 are initially charged to VCC. Cl
+ isthen switched to GND and the charge in C1
– istransferred to C2
–. Since C2+ is connected to
VCC, the voltage potential across capacitor C2 isnow 2 times VCC.
Phase 2— VSS transfer — Phase two of the clockconnects the negative terminal of C2 to the VSSstorage capacitor and the positive terminal of C2to GND. This transfers a negative generatedvoltage to C3. This generated voltage isregulated to a minimum voltage of -5.5V.Simultaneous with the transfer of the voltage toC3, the positive side of capacitor C1 is switchedto VCC and the negative side is connected toGND.
Phase 3— VDD charge storage — The third phase of theclock is identical to the first phase — the chargetransferred in C1 produces –VCC in the negativeterminal of C1, which is applied to the negativeside of capacitor C2. Since C2
+ is at VCC, thevoltage potential across C2 is 2 times VCC.
Phase 4— VDD transfer — The fourth phase of the clockconnects the negative terminal of C2 to GND,and transfers this positive generated voltageacross C2 to C4, the VDD storage capacitor. This
voltage is regulated to +5.5V. At this voltage,the internal oscillator is disabled. Simultaneouswith the transfer of the voltage to C4, thepositive side of capacitor C1 is switched to VCCand the negative side is connected to GND,allowing the charge pump cycle to begin again.The charge pump cycle will continue as long asthe operational conditions for the internaloscillator are present.
Since both V+ and V– are separately generatedfrom VCC, in a no–load condition V+ and V– willbe symmetrical. Older charge pump approachesthat generate V– from V+ will show a decrease inthe magnitude of V– compared to V+ due to theinherent inefficiencies in the design.
AUTO ON-LINE® Circuitry
The SP3223 devices have a patent pendingAUTO ON-LINE® circuitry on board that savespower in applications such as laptop computers,PDA's, and other portable systems.
The SP3223 devices incorporate an AUTOON-LINE® circuit that automatically enablesitself when the external transmitters are enabledand the cable is connected. Conversely, theAUTO ON-LINE® circuit also disables most ofthe internal circuitry when the device is not beingused and goes into a standby mode where thedevice typically draws 1µA. This function canalso be externally controlled by the ONLINEpin. When this pin is tied to a logic LOW, theAUTO ON-LINE® function is active. Onceactive, the device is enabled until there is noactivity on the receiver inputs. The receiverinput typically sees at least ±3V, which aregenerated from the transmitters at the other endof the cable with a ±5V minimum. When theexternal transmitters are disabled or the cable isdisconnected, the receiver inputs will be pulleddown by their internal 5kΩ resistors to ground.When this occurs over a period of time, theinternal transmitters will be disabled and thedevice goes into a shutdown or standby mode.When ONLINE is HIGH, the AUTO ON-LINE®
The AUTO ON-LINE® circuit has two stages:1) Inactive Detection2) Accumulated Delay
The first stage, shown in Figure 20, detects aninactive input. A logic HIGH is asserted onR
XINACT if the cable is disconnected or the
external transmitters are disabled. Otherwise,R
XINACT will be at a logic LOW. This circuit
is duplicated for each of the other receivers.
The clock rate for the charge pump typicallyoperates at above 250kHz. The external capaci-tors can be as low as 0.1µF with a 16V break-down voltage rating.
The second stage of the AUTO ON-LINE®
circuitry, shown in Figure 21, processes all thereceiver's R
XINACT signals with an accumu-
lated delay that disables the device to a 1µAsupply current.The STATUS pin goes to a logic LOW when thecable is disconnected, the external transmittersare disabled, or the SHUTDOWN pin isinvoked. The typical accumulated delay is around20µs.When the SP3223 drivers or internal chargepump are disabled, the supply current is reducedto 1µA. This can commonly occur in handheld
Figure 16. AUTO ON-LINE® Timing Waveforms
or portable applications where the RS-232 cableis disconnected or the RS-232 drivers of theconnected peripheral are turned off.
The AUTO ON-LINE® mode can be disabledby the SHUTDOWN pin. If this pin is a logicLOW, the AUTO ON-LINE® function will notoperate regardless of the logic state of theONLINE pin. Table 3 summarizes the logic of theAUTO ON-LINE® operating modes. The truthtable logic of the SP3223 driver and receiveroutputs can be found in Table 2.
The STATUS pin outputs a logic LOW signal ifthe device is shutdown. This pin goes to a logicHIGH when the external transmitters are en-abled and the cable is connected.
When the SP3223 devices are shut down, thecharge pumps are turned off. V+ charge pumpoutput decays to V
CC,the V- output decays to
GND. The decay time will depend on the size ofcapacitors used for the charge pump. Once inshutdown, the time required to exit the shutdown state and have valid V+ and V- levels istypically 200µs.
For easy programming, the STATUS can beused to indicate DTR or a Ring Indicator signal.Tying ONLINE and SHUTDOWNtogether will bypass the AUTO ON-LINE®
circuitry so this connection acts like a shutdowninput pin
ripple on the transmitter outputs and may slightlyreduce power consumption. C2, C3, and C4 canbe increased without changing C1’s value
For best charge pump efficiency locate the chargepump and bypass capacitors as close as possibleto the IC. Surface mount capacitors are best forthis purpose. Using capacitors with lowerequivalent series resistance (ESR) and self-inductance, along with minimizing parasitic PCBtrace inductance will optimize charge pumpoperation. Designers are also advised to considerthat capacitor values may shift over time andoperating temperature.
The Sipex-patented charge pumps are designedto operate reliably with a range of low costcapacitors.Either polarized or non polarizedcapacitors may be used. If polarized capacitorsare used they should be oriented as shown in theTypical Operating Circuit. The V+ capacitormay be connected to either ground or Vcc(polarity reversed.)
The charge pump operates with 0.1µF capacitorsfor 3.3V operation. For other supply voltages,see the table for required capacitor values. Donot use values smaller than those listed.Increasing the capacitorvalues (e.g., by doubling in value) reduces
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The SP3223E series incorporatesruggedized ESD cells on all driver output andreceiver input pins. The ESD structure isimproved over our previous family for morerugged applications and environments sensitiveto electro-static discharges and associatedtransients. The improved ESD tolerance is atleast +15kV without damage nor latch-up.
There are different methods of ESD testingapplied:
a) MIL-STD-883, Method 3015.7b) IEC1000-4-2 Air-Dischargec) IEC1000-4-2 Direct Contact
The Human Body Model has been the generallyaccepted ESD testing method for semiconductors.This method is also specified in MIL-STD-883,Method 3015.7 for ESD testing. The premise ofthis ESD test is to simulate the human body’spotential to store electro-static energy anddischarge it to an integrated circuit. Thesimulation is performed by using a test model asshown in Figure 22. This method will test theIC’s capability to withstand an ESD transientduring normal handling such as in manufacturingareas where the ICs tend to be handled frequently.
The IEC-1000-4-2, formerly IEC801-2, isgenerally used for testing ESD on equipment andsystems. For system manufacturers, they mustguarantee a certain amount of ESD protectionsince the system itself is exposed to the outsideenvironment and human presence. The premisewith IEC1000-4-2 is that the system is requiredto withstand an amount of static electricity whenESD is applied to points and surfaces of theequipment that are accessible to personnel during
normal usage. The transceiver IC receives mostof the ESD current when the ESD source isapplied to the connector pins. The test circuit forIEC1000-4-2 is shown on Figure 23. There aretwo methods within IEC1000-4-2, the AirDischarge method and the Contact Dischargemethod.
With the Air Discharge Method, an ESD voltageis applied to the equipment under test (EUT)through air. This simulates an electrically chargedperson ready to connect a cable onto the rear ofthe system only to find an unpleasant zap justbefore the person touches the back panel. Thehigh energy potential on the person dischargesthrough an arcing path to the rear panel of thesystem before he or she even touches the system.This energy, whether discharged directly orthrough air, is predominantly a function of thedischarge current rather than the dischargevoltage. Variables with an air discharge such asapproach speed of the object carrying the ESDpotential to the system and humidity will tend tochange the discharge current. For example, therise time of the discharge current varies with theapproach speed.
The Contact Discharge Method applies the ESDcurrent directly to the EUT. This method wasdevised to reduce the unpredictability of theESD arc. The discharge current rise time isconstant since the energy is directly transferredwithout the air-gap arc. In situations such ashand held systems, the ESD charge can be directlydischarged to the equipment from a person alreadyholding the equipment. The current is transferredon to the keypad or the serial port of the equipmentdirectly and then travels through the PCB and finallyto the IC.
RS and RV add up to 330Ω for IEC1000-4-2.RS and RV add up to 330Ω for IEC1000-4-2.
Contact-Discharge Module
RVRC
CS
RS
SW1 SW2
RC
DeviceUnderTest
DC PowerSource
CS
RS
SW1 SW2
RV
Contact-Discharge Module
The circuit model in Figures 22 and 23 representthe typical ESD testing circuit used for all threemethods. The CS is initially charged with the DCpower supply when the first switch (SW1) is on.Now that the capacitor is charged, the secondswitch (SW2) is on while SW1 switches off. Thevoltage stored in the capacitor is then appliedthrough RS, the current limiting resistor, onto thedevice under test (DUT). In ESD tests, the SW2switch is pulsed so that the device under testreceives a duration of voltage.
For the Human Body Model, the current limitingresistor (R
S) and the source capacitor (C
S) are
1.5kΩ an 100pF, respectively. For IEC-1000-4-2, the current limiting resistor (R
S) and the source
capacitor (CS) are 330Ω an 150pF, respectively.
The higher CS value and lower R
S value in the
IEC1000-4-2 model are more stringent than theHuman Body Model. The larger storage capacitorinjects a higher voltage to the test point whenSW2 is switched on. The lower current limitingresistor increases the current charge onto the testpoint.
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the applica-tion or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
Sipex Corporation
Headquarters andSales Office233 South Hillview DriveMilpitas, CA 95035TEL: (408) 934-7500FAX: (408) 935-7600
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of theapplication or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.
Contact factory for availability of the following legacy part numbers. For long term availabilitySipex recommends upgrades as listed below. All upgrade part numbers shown are fully pinoutand function compatible with legacy part numbers. Upgrade part numbers may containfeature and/or performance enhancements or other changes to datasheet parameters.