SP233A,SP310A and SP312A
Enhanced RS-232 Line Drivers/Receivers
FEATURES
• Operates from a Single +5V Power Supply
• Meets all RS-232F and ITU V.28 Specifications
• Operates with 0.μF Ceramic Capacitors
• No External Capacitors required (SP233A)
• Low Power Shutdown (SP30A, SP32A)
• High Data Rate - 20kbps under load
• Low power CMOS Operation
• +/-2kV Human Body Model ESD Protection
• Lead Free packaging available
The SP233A / SP30A / SP32A devices are a family of line driver and receiver pairs that meets
the specifications of RS-232 and V.28 serial protocols. The devices are pin-to-pin compatible with
popular industry standard pinouts. The SP233A / SP30A / SP32A offer 20kbps data rate under
load, small ceramic type 0.μF charge pump capacitors and overall ruggedness for comercial appli-
cations. Features include Exar's BiCMOS design allowing for low power operation without sacrificing
performance. These devices are available in plastic DIP and SOIC Wide packages operating over
the commercial and industrial temperature ranges.
DESCRIPTION
SELECTION TABLE
Model
Number of RS-232
Drivers
Receivers
No. of RX
active in
Shutdown
No. of External
0.
μ
F Capacitors
Shutdown
WakeUp
TTL Tri-State
SP233A
SP30A
SP32A
2
2
2
2
2
2
N/A
0
2
0
4
4
No
Yes
Yes
No
No
Yes
No
Yes
Yes
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (50)668-7000 • Fax (50)668-707 • www.exar.com SP233A,30A,32A 0_0603
These are stress ratings only and functional opera-
tion of the device at these ratings or any other above
those indicated in the operation sections of the speci-
fications below are not implied. Exposure to absolute
maximum ratings conditions for extended periods of
time may affect reliability.
Supply Voltage (V
CC
)....................................................+ 6V
V+........................................................................... (Vcc-0.3V) to +.0V
V- .............................................................................-.0V
Input Voltages
Tin.....................................................-0.3V to (Vcc + 0.3V)
Rin............................................................................+/-30V
Output Voltages
Tout...............................................(V+, +0.3V) to (V-, -0.3V
Rout...................................................-0.3V to (Vcc + 0.3V)
AbSoLUTE MAxiMUM RATingS
Short Circuit duration
Tout.....................................................Continuous
Package Power Dissipation:
Plastic DIP...............................................375mW
(derate 7mW/°C above +70°C)
Small Outline...........................................375mW
(derate 7mW/°C above +70°C)
Storage Temperature..................-65°C to +50°C
Lead Temperature (soldering, 0s).......... +300°C
Vcc=5V ±0%, 0.
μ
F charge pump capacitors, T
min
to T
max
, unless otherwise noted, Typical values are Vcc=5V
and T
a
=25°C
PARAMETER
TTL inPUT
Logic Threshold LOW
Logic Threshold HIGH
Logic Pull-Up Current
TTL oUTPUT
Output Voltge LOW
Output Voltage HIGH
Leakage Current;
T
a
=25°C
RS-232 oUTPUT
Output Voltage Swing
Output Resistance
Output Short Circuit Current
Maximum Data Rate
RS-232 inPUT
Voltage Range
Voltage Threshold LOW
Voltage Threshold HIGH
Hysteresis
Resistance
Vcc = 5V,
T
a
=25°C
Vcc = 5V,
T
a
=25°C
Vcc = 5V,
T
a
=25°C
0.2
3
-25
0.8
.2
.7
0.5
5
2.4
.0
7
+25
Volts
Volts
Volts
Volts
kΩ
all Transmitter outputs loaded
with 3k ohms to GND
Vcc = 0V, Vout = +/-2V
Infinite Duration
CL = 2500pF, RL = 3kΩ
20
+/-5.0
300
+/-8
240
+/-9V
Volts
Ohms
mA
kbps
i
OuT
= 3.2ma: V
cc
= +5V
i
OuT
= -1.0ma
En = V
cc
,
0V ≤ V
OuT
≤ Vcc
SP30A and SP32A only
3.5
0.05
+/-0
0.4
Volts
Volts
μA
Tin, En, SD, On/OFF
Tin, En, SD, On/OFF
Tin = 0V
2.0
5
200
0.8
Volts
Volts
μA
TEST ConDiTionS
Min
TYP
MAx
UniT
ELECTRiCAL CHARACTERiSTiCS
T
a
=25°C,
-25V ≤ V
in
≤ +25V
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (50)668-7000 • Fax (50)668-707 • www.exar.com SP233A,30A,32A_0_0603
2
Vcc=5V ±0%, 0.
μ
F charge pump capacitors, T
min
to T
max
, unless otherwise noted, Typical values are Vcc=5V
and T
a
=25°C
Parameter
DYnAMiC CHARACTERiSTiCS
Driver Propagation Delay
Receiver Propagation Delay
Instantaneous Slew Rate
Transition Region Slew Rate
Output Enable Time
Output Disable Time
PoWER REQUiREMEnTS
Vcc Power Supply Current
Vcc Power Supply Current, Loaded
Shutdown Supply Current
SP30A and SP32A only
No Load, Vcc = 5V, T
a
=25°C
All Transmitters RL = 3kΩ,
T
a
=25°C
Vcc = 5V, T
a
=25°C
0
25
0
5
mA
mA
μA
TTL to RS_232; CL = 50pF
RS-232 to TTL,
CL = 10pF, RL = 3-7kΩ
CL = 2500pF, RL = 3kΩ;
Measured from +3V to -3V or
-3V to +3V
SP30A and SP32A only
SP30A and SP32A only
0
400
250
.5
0.
3.0
.0
30
μs
μs
V/ μs
V/ μs
ns
ns
TEST CONDITIONS
MIN
TYP
MAX
Unit
ELECTRiCAL CHARACTERiSTiCS
Pin ASSignMEnTS
20 pin PDIP
20 pin WSOIC
8 pin WSOIC
3
8 pin WSOIC
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (50)668-7000 • Fax (50)668-707 • www.exar.com SP233A,30A,32A 0_0603
DETAiLED DESCRiPTion
The SP233A, SP30A and SP32A devices
are a family of line driver and receiver pairs that
meet the EIA/TIA-232 and V.28 serial commu-
nication protocols. These devices are pin-to-pin
compatible with popular industry standards. The
SP233A, SP30A and SP32A devices offer a
20kbps data rate, 0V/
μ
s slew rate and an on-
board charge pump that operates from a single
5V supply using 0.
μ
F ceramic capacitors. The
ESD tolerance has been improved on these de-
vices to +/-2kV Human Body Model.
The SP233A device provides internal charge
pump capacitors. The SP30A provides an ON/
OFF input that simultaneously disables the in-
ternal charge pump circuit and puts all transmit-
ter and receiver outputs into a high impedance
state. The SP32A is identical to the SP30 but
with seperate tri-state and shutdown inputs
Theory of operation
The SP233A, SP30A and SP32A devices are
made up of three basic circuit blocks: . Drivers,
2. Receivers, and 3. charge pump.
Drivers
The drivers are inverting level transmitters that
convert TTL or CMOS logic levels to EIA/TIA-
232 levels with an inverted sense relative to the
input logic levels. Typically, the driver output
voltage swing is +/-9V. Even under worst case
loading conditions of 3k ohms and 2500pF, the
driver output is guaranteed to be +/-5.0V mini-
mum, thus satisfying the RS-232 specification.
The driver outputs are protected against infinite
short-circuits to ground without degradation in
reliability.
The drivers can guarantee output data rates of
20kbps under worst case loading of 3k ohms
and 2500pF.
The Slew rate of the driver output is internally
limited to 30V/
μ
s in order to meet the EIA stan-
dards (EIA-232F). Additionally, the driver out-
puts LOW to HIGH transition meets the mon-
tonic output requirements of the standard.
Receivers
The receivers convert EIA/TIA-232 signal levels
to TTL or CMOS logic output levels. Since the
input is usually from a transmission line, where
long cable length and system interference can
degrade the signal, the inputs have a typical
hysteresis margin of 500mV. This ensures that
the receiver is virtually immune to noisy trans-
mission lines. Should an input be left uncon-
nected, an internal 5kohm pull-down resistor to
ground will commit the output of the receiver to
a HIGH state.
Charge pump
The charge pump is a patented design and
uses a unique approach compared to older
less efficiant designs. The charge pump re-
quires 4 external capacitors and uses a four
phase voltage shifting technique. The internal
power supply consists of a dual charge pump
that provides a driver output voltage swing of
+/-9V. The internal oscillator controls the four
phases of the voltage shifting. A description of
each phase follows:
Phase 1
Vss charge store and double: The positive ter-
minals of capacitors C and C2 are charged
from Vcc with their negative terminals initially
connected to ground. C+ is then connected
to ground and the stored charge from C- is
superimposed onto C2-. Since C2+ is still con-
nected to Vcc the voltage potential across C2
is now 2 x Vcc.
Phase 2
Vss transfer and invert: Phase two connects
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. Meanwhile, capacitor C
is charged from Vcc to prepare it for its next
phase.
Phase 3
Vdd charge store and double: Phase three is
identical to the first phase. The positive termi-
nals of C and C2 are charged from Vcc with
their negative terminals initially connected to
ground. C+ is then connected to ground and
the stored charge from C- is superimposed
onto C2-. Since C2+ is still connected to Vcc
the voltage potential across capacitor C2 is
now 2 x Vcc.
DESCRiPTion
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (50)668-7000 • Fax (50)668-707 • www.exar.com SP233A,30A,32A_0_0603
4
DESCRiPTion
Phase 4
Vdd transfer: The fourth phase connects the
negative terminal of C2 to ground and the posi-
tive terminal of C2 to the Vdd storage capacitor.
This transfers the doubled (V+) voltage onto C3.
Meanwhile, capacitor C is charged from Vcc to
prepare it for its next phase.
The clock rate for the charge pump typically op-
erates at greater than 5kHz allowing the pump
to run efficiently with small 0.1uF capacitors. Ef-
ficient operation depends on rapid charging and
discharging of C and C2, therefore capacitors
should be mounted as close as possible to the
IC and have low ESR (equivalent series resis-
tance). Inexpensive surface mount, ceramic ca-
pacitors are ideal for using on charge pump. If
polarized capacitors are used the positive and
negative terminals should be connected as
shown in the typical operating circuit. A diagram
of the individual phases are shown in Figure .
Shutdown (SD) and Enable (En) features for
the SP310A and SP312A
Both the SP30A and SP32A have a shutdown
/ standby mode to conserve power in battery-
powered applications. To activate the shutdown
mode, which stops the operation of the charge
pump, a logic "0" is applied to the appropriate
control line. For the SP30A, this control line is
the ON/OFF (pin 8) input. Activating the shut-
down mode puts the SP30A transmitter and re-
ceiver ouptuts into a high impedance condition.
For the SP32A, this control line is the SHUT-
DOWN (pin8) input; this also puts the transmit-
ter outputs in a tri-state mode. The receiver out-
puts can be tri-stated seperately during normal
operation or shutdown by applying a logic "" on
the EN line (pin ).
Wake-Up Feature for the SP312A
The SP32A has a wake-up feature that keeps
the receivers active when the device is placed
into shutdown. Table 1 defines the truth table for
the Wake-Up function. When only the receivers
are activated, the SP32A typically draws less
than 5uA supply current. In the case of when
a modem is interfaced to a computer in power
down mode, the Ring Indicator (RI) signal from
the modem would be used to "wake-up" the
computer, allowing it to accept data transmis-
sion.
After the ring indicator has propagated
through the SP32A receiver, it can be used
to trigger the power management circuitry of
the computer to power up the microproces-
sor, and bring the SD pin of the SP32A to a
logic high, taking it out of the shutdown mode.
The receiver propagation delay is typically
us. The enable time for V+ and V- is typi-
cally 2ms. After V+ and V- have settled to their
final values, a signal can be sent back to the
modem on the data terminal ready (DTR) pin
signifying that the computer is ready to accept
the transmit data.
SD
0
0
EN
0
0
Power
Receiver
Up/Down outputs
Down
Down
Up
Up
Enabled
Tri-state
Enabled
Tri-state
Table . Wake-up Function truth table
Pin Strapping for the SP233ACT/ACP
The SP233A packaged in a 20 pin SOICW
package (SP233ACT) has a slightly different
pinout than the SP233A in PDIP packaging
(SP233ACP). To operate properly, the fol-
lowing pairs of pins must be externally wired
together as noted in table 2:
Pins Wired
Together
Two V- pins
Two C- pins
SOICW
0 & 7
& 6
PDIP
2 & 7
& 5
0 & 6
Two C2+ pins 2 & 5
No Connections for
Pins 8, 3 and 4
Connect Pins 6 and 9
to GND
Table 2. Pin Strapping table for SP233A
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (50)668-7000 • Fax (50)668-707 • www.exar.com SP233A,30A,32A 0_0603
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