■ Meets true EIA/TIA-232-F Standards
from a +3.0V to +5.5V power supply
■ 250kbps Transmission Rate Under Load
■ 1µA Low-Power Shutdown with Receivers
Active (SP3222EB)
■ Interoperable with RS-232 down to +2.7V
power source
■ Enhanced ESD Specifications:
±15kV Human Body Model±15kV IEC1000-4-2 Air Discharge
±8kV IEC1000-4-2 Contact Discharge
DESCRIPTION
The SP3222EB/3232EB series is an RS-232 transceiver solution intended for portable or
hand-held applications such as notebook or palmtop computers. The SP3222EB/3232EB
series has a high-efficiency, charge-pump power supply that requires only 0.1µF capacitors
in 3.3V operation. This charge pump allows the SP3222EB/3232EB series to deliver true RS-
232 performance from a single power supply ranging from +3.0V to +5.5V. The SP3222EB/
3232EB are 2-driver/2-receiver devices. This series is ideal for portable or hand-held
applications such as notebook or palmtop computers. The ESD tolerance of the SP3222EB/
3232EB devices are over ±15kV for both Human Body Model and IEC1000-4-2 Air discharge
test methods. The SP3222EB device has a low-power shutdown mode where the devices'
driver outputs and charge pumps are disabled. During shutdown, the supply current falls to
less than 1µA.
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 specifications below is not implied. Exposure to
absolute maximum rating conditions for extended
periods of time may affect reliability and cause
permanent damage to the device.
VCC...................................................... -0.3V to +6.0V
V+ (NOTE 1) ...................................... -0.3V to +7.0V
V- (NOTE 1) ....................................... +0.3V to -7.0V
NOTE 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
NOTE 2: Driver Input hysteresis is typically 250mV.
SPECIFICATIONS
Unless otherwise noted, the following specifications apply for VCC = +3.0V to +5.5V with T
C4=0.1µF
PARAMETERMIN.TYP.MAX.UNITSCONDITIONS
DC CHARACTERISTICS
Unless otherwise noted, the following performance characteristics apply for VCC = +3.3V, 250kbps data rates, all drivers
loaded with 3kΩ, 0.1µF charge pump capacitors, and T
= +25°C.
AMB
6
4
2
0
-2
Voltage (V)
-4
Transmitter Output
-6
010002000300040005000
TxOUT +
TxOUT -
T1 at 250Kbps
T2 at 15.6Kbps
All TX loaded 3K // CLoad
Load Capacitance (pF)
Figure 1. Transmitter Output Voltage vs Load
Capacitance.
35
T1 at Full Data Rate
30
T2 at 1/16 Data Rate
All TX loaded 3K // CLoad
25
20
15
10
Supply Current (mA)
5
0
010002000300040005000
Load Capacitance (pF)
250Kbps
125Kbps
20Kbps
30
25
20
15
10
Slew rate (V/µs)
5
0
05001000 2000 3000 4000 5000
T1 at 250Kbps
T2 at 15.6Kbps
All TX loaded 3K // CLoad
Load Capacitance (pF)
Figure 2. Slew Rate vs Load Capacitance.
16
14
12
10
8
6
1 Transmitter at 250Kbps
1 Transmitter at 15.6Kbps
4
Supply Current (mA)
All transmitters loaded with 3K // 1000pf
2
0
2.733.544.55
Supply Voltage (V)
- Slew
+ Slew
Figure 3. Supply Current vs Load Capacitance when
Figure 4. Supply Current vs Supply Voltage.
Transmitting Data.
6
4
2
0
Voltage (V)
-2
Transmitter Output
-4
-6
2.733.544.55
TxOUT +
T1 at 250Kbps
T2 at 15.6Kbps
All TX loaded 3K // 1000 pF
TxOUT -
Supply Voltage (V)
Figure 5. Transmitter Output Voltage vs Supply
Voltage.
The SP3222EB/3232EB transceivers meet the
EIA/TIA-232 and V.28/V.24 communication
protocols and can be implemented in batterypowered, portable, or hand-held applications
such as notebook or palmtop computers. The
SP3222EB/3232EB devices all feature Sipex's
proprietary on-board charge pump circuitry that
generates 2 x V
for RS-232 voltage levels
CC
from a single +3.0V to +5.5V power supply.
This series is ideal for +3.3V-only systems,
mixed +3.3V to +5.5V systems, or +5.0V-only
systems that require true RS-232 performance.
The SP3222EB/3232EB series have drivers that
operate at a typical data rate of 250kbps fully
loaded.
The SP3222EB and SP3232EB are 2-driver/2-
receiver devices ideal for portable or hand-held
applications. The SP3222EB features a 1µA
shutdown mode that reduces power consumption and extends battery life in portable systems.
Its receivers remain active in shutdown mode,
allowing external devices such as modems to be
monitored using only 1µA supply current.
THEORY OF OPERATION
The SP3222EB/3232EB series are made up of
three basic circuit blocks: 1. Drivers, 2.
Receivers, and 3. the Sipex proprietary charge
pump.
Drivers
The drivers are inverting level transmitters that
convert TTL or CMOS logic levels to ±5.0V
EIA/TIA-232 levels inverted relative to the input logic levels. Typically, the RS-232 output
voltage swing is ±5.5V with no load and at least
±5V minimum fully loaded. The driver outputs
are protected against infinite short-circuits to
ground without degradation in reliability. Driver
outputs will meet EIA/TIA-562 levels of ±3.7V
with supply voltages as low as 2.7V.
The drivers can guarantee a data rate of 250kbps
fully loaded with 3KΩ in parallel with 1000pF,
ensuring compatibility with PC-to-PC communication software.
The slew rate of the driver output 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 transition of the loaded
output from HIGH to LOW also meets the
monotonicity requirements of the standard.
Figure 10 shows a loopback test circuit used to
the RS-232 drivers. Figure 11 shows the test
results of the loopback circuit with all drivers
active at 120kbps with RS-232 loads in parallel
with 1000pF capacitors. Figure 12 shows the
test results where one driver was active at
250kbps and all drivers loaded with an RS-232
receiver in parallel with a 1000pF capacitor. A
solid RS-232 data transmission rate of 250kbps
provides compatibility with many designs in
personal computer peripherals and LAN applications.
The SP3222EB driver's output stages are turned
off (tri-state) when the device is in shutdown
mode. When the power is off, the SP3222EB
device permits the outputs to be driven up to
±12V. The driver's inputs do not have pull-up
resistors. Designers should connect unused inputs to V
or GND.
CC
In the shutdown mode, the supply current falls
to less than 1µA, where SHDN = LOW. When
the SP3222EB device is shut down, the device's
driver outputs are disabled (tri-stated) and the
charge pumps are turned off with V+ pulled
down to VCC and V- pulled to GND. The time
required to exit shutdown is typically 100µs.
Connect SHDN to VCC if the shutdown mode is
not used.
Figure 12. Driver Loopback Test Results at 250 kbps
9
Page 10
Receivers
The receivers convert EIA/TIA-232 levels to
TTL or CMOS logic output levels. The
SP3222EB receivers have an inverting tri-state
output. These receiver outputs (RxOUT) are tristated when the enable control EN = HIGH. In
the shutdown mode, the receivers can be active
or inactive. EN has no effect on TxOUT. The
truth table logic of the SP3222EB driver and
receiver outputs can be found in Table 2.
Since receiver input is usually from a transmission line where long cable lengths and system
interference can degrade the signal, the inputs
have a typical hysteresis margin of 300mV. This
ensures that the receiver is virtually immune to
noisy transmission lines. Should an input be left
unconnected, a 5kΩ pulldown resistor to ground
will commit the output of the receiver to a HIGH
state.
Charge Pump
The charge pump is a Sipex–patented design
(5,306,954) and uses a unique approach compared to older less–efficient 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 input voltage (VCC) over
the +3.0V to +5.5V range.
In most circumstances, decoupling the power
supply can be achieved adequately using a 0.1µF
bypass capacitor at C5 (refer to Figures 8 and 9).
NDHSNETUOxTTUOxR
00etats-irTevitcA
01etats-irTetats-irT
In applications that are sensitive to power-supply noise, decouple VCC to ground with a capacitor of the same value as charge-pump capacitor
C1. Physically connect bypass capacitors as
close to the IC as possible.
The charge pumps operate in a discontinuous
mode using an internal oscillator. If the output
voltages are less than a magnitude of 5.5V, the
charge pumps are enabled. If the output voltage
exceed a magnitude of 5.5V, the charge pumps
are disabled. This oscillator controls the four
phases of the voltage shifting. A description of
each phase follows.
Phase 1
— VSS charge storage — During this phase of
the clock cycle, the positive side of capacitors
C1 and C2 are initially charged to VCC. C
then switched to GND and the charge in C
transferred to C
–
. Since C
2
+
is connected to
2
VCC, the voltage potential across capacitor C
+
is
l
–
is
1
2
is now 2 times VCC.
Phase 2
— VSS transfer — Phase two of the clock connects the negative terminal of C2 to the V
storage capacitor and the positive terminal of C
to GND. This transfers a negative generated
voltage to C3. This generated voltage is regulated to a minimum voltage of -5.5V. Simultaneous with the transfer of the voltage to C3, the
positive side of capacitor C1 is switched to V
CC
and the negative side is connected to GND.
Phase 3
— VDD charge storage — The third phase of the
clock is identical to the first phase — the charge
transferred in C1 produces –VCC in the negative
terminal of C1, which is applied to the negative
side of capacitor C2. Since C
+
is at VCC, the
2
voltage potential across C2 is 2 times VCC.
SS
2
10evitcAevitcA
Phase 4
— VDD transfer — The fourth phase of the clock
11evitcAetats-irT
Table 2. SP3222EB Truth Table Logic for Shutdown
and Enable Control
connects the negative terminal of C2 to GND,
and transfers this positive generated voltage
across C2 to C4, the VDD storage capacitor.
10
Page 11
This voltage is regulated to +5.5V. At this
voltage, the internal oscillator is disabled. Simultaneous with the transfer of the voltage to
C4, the positive side of capacitor C1 is switched
to VCC and the negative side is connected to
GND, allowing the charge pump cycle to begin
again. The charge pump cycle will continue as
long as the operational conditions for the internal oscillator are present.
Since both V+ and V– are separately generated
from VCC; in a no–load condition V+ and V– will
be symmetrical. Older charge pump approaches
that generate V– from V+ will show a decrease in
the magnitude of V– compared to V+ due to the
inherent inefficiencies in the design.
The clock rate for the charge pump typically
operates at 250kHz. The external capacitors can
be as low as 0.1µF with a 16V breakdown
voltage rating.
ESD Tolerance
The SP3222EB/3232EB series incorporates
ruggedized 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 electrostatic 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 specified in MIL-STD883, Method 3015.7 for ESD testing. The premise
of this ESD test is to simulate the human body’s
potential to store electrostatic energy and
discharge it to an integrated circuit.
The simulation is performed by using a test
model as shown in Figure 18. This method
will test the IC’s capability to withstand an
ESD transient during normal handling such as
in manufacturing areas where the ICs tend to
be handled frequently.
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 presence.
The premise with IEC1000-4-2 is that the
system is required to withstand 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 19. There are two methods
within IEC1000-4-2, the Air Discharge method
and the Contact Discharge method.
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 find
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
current directly 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 situations 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 finally to the IC.
SW2
SW2
C
C
S
S
Device
Under
Test
The circuit models in Figures 18 and 19
represent the typical ESD testing circuits used
for all three methods. The CS is initially charged
with the DC power supply when the first
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 the source capacitor
(CS) are 1.5kΩ an 100pF, respectively. For
I ➙
30A
IEC-1000-4-2, the current limiting resistor (RS)
and the source capacitor (CS) are 330Ω an
150pF, respectively.
15A
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
0A
is switched on. The lower current limiting resistor
increases the current charge onto the test point.
SP3222EBCA .......................................... 0˚C to +70˚C .......................................... 20-Pin SSOP
SP3222EBCP .......................................... 0˚C to +70˚C ............................................18-Pin PDIP
SP3222EBCT........................................... 0˚C to +70˚C ........................................ 18-Pin WSOIC
SP3222EBCY .......................................... 0˚C to +70˚C ........................................ 20-Pin TSSOP
SP3222EBEA.......................................... -40˚C to +85˚C ........................................ 20-Pin SSOP
SP3222EBEP.......................................... -40˚C to +85˚C .......................................... 18-Pin PDIP
SP3222EBET .......................................... -40˚C to +85˚C ...................................... 18-Pin WSOIC
SP3222EBEY.......................................... -40˚C to +85˚C ...................................... 20-Pin TSSOP
SP3232EBCA .......................................... 0˚C to +70˚C .......................................... 16-Pin SSOP
SP3232EBCP .......................................... 0˚C to +70˚C ............................................16-Pin PDIP
SP3232EBCT........................................... 0˚C to +70˚C ........................................ 16-Pin WSOIC
SP3232EBCN .......................................... 0˚C to +70˚C ......................................... 16-Pin nSOIC
SP3232EBCY .......................................... 0˚C to +70˚C ........................................ 16-Pin TSSOP
SP3232EBEA.......................................... -40˚C to +85˚C ........................................ 16-Pin SSOP
SP3232EBEP.......................................... -40˚C to +85˚C .......................................... 16-Pin PDIP
SP3232EBET .......................................... -40˚C to +85˚C ...................................... 16-Pin WSOIC
SP3232EBEN ......................................... -40˚C to +85˚C ....................................... 16-Pin nSOIC
SP3232EBEY.......................................... -40˚C to +85˚C ...................................... 16-Pin TSSOP
Please consult the factory for pricing and availability on a Tape-On-Reel option.
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation
Headquarters and
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
Sales Office
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the
application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.