The Sipex SP231A, SP232A and SP233A are enhanced versions of the Sipex SP231, SP232
and SP233 RS-232 line drivers/receivers. They are pin-for-pin replacements for these earlier
versions and will operate in their sockets. Performance enhancements include 10V/µs slew rate,
120k bits per second guaranteed transmission rate, and increased drive current for longer and
more flexible cable configurations. Ease of use enhancements include smaller, 0.1µF charge
pump capacitors, enhanced ESD protection, low power dissipation and overall ruggedized
construction for commercial environments. The series is available in plastic and ceramic DIP and
SOIC packages operating over the commercial, industrial and military temperature ranges.
This is a stress rating only and functional operation of the device at
these or any other conditions above those indicated in the operation
sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods of time may affect
reliability.
The Sipex SP231A, SP232A and SP233A are
enhanced versions of the Sipex SP231, SP232
and SP233 RS-232 line drivers/receivers. They arepin-
for-pin replacements for these earlier versions, will
operate in their sockets with capacitors ranging from
0.1 to 100µF, either polarized or non–polarized, and
feature several improvements in both performance
and ease of use. Performance enhancements include
10V/µs slew rate, 120k bits per second guaranteed
transmission rate, and increased drive current for
longer and more flexible cable configurations. Ease of
use enhancements include smaller, 0.1µF charge pump
capacitors, enhanced ESD protection, low power
dissipation and overall ruggedized construction for
commercial environments.
The SP232A, SP233A, SP310A and SP312A
include charge pump voltage converters which allow
them to operate from a single +5V supply. These
converters convert the +5V input power to the ±10V
needed to generate the RS-232 output levels. Both
meet all EIA RS-232D and CCITT V.28 specifications. The SP231A has provisions for external V+
supplies. With this power supplied externally, the
current drain due to charge pump operation is
considerably reduced, typically to 400µA.
The SP310A provides identical features as the
SP232A. The SP310A has a single control line
which simultaneously shuts down the internal DC/
DC converter and puts all transmitter and receiver
outputs into a high impedance state. The SP312A
is identical to the SP310A with separate tri-state
and shutdown control lines.
The SP231A is available in 14-pin plastic DIP,
CERDIP and 16-pin SOIC packages for operation over commercial, industrial and military
temperature ranges. The SP232A is available
in 16-pin plastic DIP, SOIC and CERDIP
packages, operating over the commercial,
industrial and military temperature ranges. The
SP233A is available in a 20-pin plastic DIP and
20–pin SOIC package for operation over the
commercial and industrial temperature ranges.
The SP310A and SP312A are available in
18-pin plastic, CERDIP and SOIC packages
for operation over the commercial and industrial
temperature ranges. Please consult the factory
for DIP and surface-mount packaged parts
supplied on tape-on-reel, as well as parts screened
to MIL-M-38510.
THEORY OF OPERATION
The SP231A, SP232A, SP233A, SP310A and
SP312A devices are made up of three basic circuit
blocks – 1) a driver/transmitter, 2) a receiver and 3)
a charge pump. Each block is described below.
Driver/Transmitter
The drivers are inverting transmitters, which
accept TTL or CMOS inputs and output the
RS-232 signals with an inverted sense relative to
the input logic levels. Typically the RS-232 output
voltage swing is ±9V. Even under worst case
loading conditions of 3kOhms and 2500pF, the
output is guaranteed to be ±5V, which is consistent
with the RS-232 standard specifications. The
transmitter outputs are protected against infinite
short-circuits to ground without degradation in
reliability.
The instantaneous slew rate of the transmitter
output is internally limited to a maximum of 30V/
µs in order to meet the standards [EIA RS-232-D
2.1.7, Paragraph (5)]. However, the transition
region slew rate of these enhanced products is
typically 10V/µs. The smooth transition of the
loaded output from VOL to VOH clearly meets the
monotonicity requirements of the standard [EIA
RS-232-D 2.1.7, Paragraphs (1) & (2)].
V
CC
GND
INTERNAL
OSCILLATOR
Figure 1. Charge Pump Voltage DoublerFigure 2. Charge Pump Voltage Inverter
The receivers convert RS-232 input signals to
inverted TTL signals. Since the 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 500mV.
This ensures that the receiver is virtually immune
to noisy transmission lines.
As shown in Figure 1, an internal oscillator triggers the charge accumulation and voltage inversion. The voltage doubler momentarily stores a
charge on capacitor C1 equal to Vcc, referenced to
ground. During the next transition of the oscillator
this charge is boot-strapped to transfer charge to
capacitor C3. The voltage across C3 is now from
Vcc to V+.
The input thresholds are 0.8V minimum and
2.4V maximum, again well within the ±3V
RS-232 requirements. The receiver inputs are also
protected against voltages up to ±30V. Should an
input be left unconnected, a 5kOhm pulldown
resistor to ground will commit the output of the
receiver to a high state.
In actual system applications, it is quite possible
for signals to be applied to the receiver inputs
before power is applied to the receiver circuitry.
This occurs, for example, when a PC user attempts
to print, only to realize the printer wasn’t turned on.
In this case an RS-232 signal from the PC will
appear on the receiver input at the printer. When
the printer power is turned on, the receiver will
operate normally. All of these enhanced devices
are fully protected.
Charge Pump
The charge pump section of the these devices
allows the circuit to operate from a single +5V
±10% power supply by generating the required
operating voltages internal to the devices. The
charge pump consists of two sections — 1) a
voltage doubler and 2) a voltage inverter.
In the inverter section (Figure 2), the voltage
across C3 is transferred to C2 forcing a range of 0V
to V+ across C2. Boot-strapping of C2 will then
transfer charge to C4 to genrate V-.
One of the significant enhancements over
previous products of this type is that the values of
the capacitors are no longer critical and have been
decreased in size considerably to 0.1µF. Because
the charge pump runs at a much higher frequency,
the 0.1µF capacitors are sufficient to transfer and
sustain charges to the two transmitters.
APPLICATION HINTS
Protection From Shorts to ±15V
The driver outputs are protected against shorts
to ground, other driver outputs, and V+ or V-.
If the possibility exists that the outputs could be
inadvertently connected to voltages higher than
±15V, then it is recommended that external
protection be provided. For protection against
voltages exceeding ±15V, two back-to-back zener
diodes connected from each output to ground will
clamp the outputs to an acceptable voltage level.
+5V INPUT
10 F 6.3V
+5V INPUT
V+ (+8.5V to +13.2V)
C +
1
C -
1
SP231A
V
CC
+12V to -12V
Voltage Inverter
400k
Ω
400k Ω
R
1
R
2
13
V+
V-
T
1
T
2
5k
Ω
5k
Ω
12GND
1
+
0.1 F
µ
6.3V
2
8
T IN
1
7
T IN
2
TTL/CMOS INPUTS
910
1
65
2
TTL/CMOS OUTPUTS
0.1 F
14
µ
0.1 F
16V
3
+
11
T OUT
1
4
T OUT
2
RS-232 OUTPUTS
R INR OUT
1
R INR OUT
2
RS-232 INPUTS
6.3V
0.1 F
16V
T IN
1
T IN
2
TTL/CMOS INPUTS
1
2
TTL/CMOS OUTPUTS
*The negative terminal of the V+ storage capacitor can be tied
to either V
is recommended.
µ
+
C +
1
C -
1
C +
2
C -
2
SP232A
V
CC
+5V to +10V
Voltage Doubler
+10V to -10V
Voltage Inverter
400k
Ω
400k Ω
R
1
R
2
16
15GND
0.1 F 6.3V
µ
2
+
V+
V-
T
1
T
2
5k
Ω
5k
Ω
*
6
+
0.1 F
µ
16V
14
T OUT
1
7
T OUT
2
R INR OUT
1
R INR OUT
2
1
+
µ
3
4
+
µ
5
11
10
1213
98
or GND. Connecting the capacitor to VCC (+5V)
CC
RS-232 OUTPUTS
RS-232 INPUTS
Figure 3. Typical Circuits using the SP231A and 232A.
Figure 4. Typical Circuits using the SP233ACP and SP233ACT
Shutdown (SD) and Enable (EN)
SP310A/SP312A Only
Both the SP310A and SP312A have a shut-down/
standby mode to conserve power in battery-powered systems. 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 SP310A, this control line is ON/OFF (pin
18). Activating the shutdown mode also puts the
SP310A transmitter and receiver outputs in a high
impedance condition (tri-stated). The shutdown
mode is controlled on the SP312A by a logic “0”
on the SHUTDOWN control line (pin 18); this also
puts the transmitter outputs in a tri–state mode.
The receiver outputs can be tri–stated separately
during normal operation or shutdown by a logic
“1” on the ENABLE line (pin 1).
Wake–Up Feature (SP312A Only)
The SP312A has a wake–up feature that keeps
all the receivers in an enabled state when the
device is in the shutdown mode. Table 1 defines
the truth table for the wake–up function.
7
V
CC
400k Ω
2
T IN
1
400k Ω
1
T IN
2
TTL/CMOS INPUTS
34
1
2
TTL/CMOS OUTPUTS
Do not make
connection to
these pins
Internal
-10V Power
Supply
Internal
+10V Power
Supply
R
1
2019
R
2
13
C +
1
14
C -
1
10
V-
17
V-
SP233ACT
8
V+
GND
6
5
T
1
T
2
5k
Ω
5k
Ω
GND
9
T OUT
1
18
T OUT
2
RS-232 OUTPUTS
R INR OUT
1
R INR OUT
2
RS-232 INPUTS
12
C +
2
15
C +
2
11
C -
2
16
2
C -
After the ring indicator signal has propagated
through the SP312A receiver, it can be used to
trigger the power management circuitry of the
computer to power up the microprocessor, and
bring the SD pin of the SP312A to a logic high,
taking it out of the shutdown mode. The receiver
propagation delay is typically 1µs. The enable
time for V+ and V– is typically 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 and transmit data.
Pin Strapping — SP233ACT Only
The SP233A packaged in the 20–pin SOIC
package (SP233ACT) has a slightly different
pinout than the SP233A in other package
configurations. To operate properly, the following
pairs of pins must be externally wired together:
the two V– pins (pins 10 and 17)
the two C2+ pins (pins 12 and 15)
the two C2– pins (pins 11 and 16)
With only the receivers activated, the SP312A
typically draws less than 5µA supply current
(10µA maximum). In the case of a modem
All other connections, features, functions and
performance are identical to the SP233A as
specified elsewhere in this data sheet.
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 transmission.
Model .......................................................................................Temperature Range................................................................................ Package
ORDERING INFORMATION
SP231ACP ..................................................................................... 0°C to +70°C ....................................................................... 14–pin Plastic DIP
SP231ACT ..................................................................................... 0°C to +70°C ................................................................................ 16–pin SOIC
SP231ACX ..................................................................................... 0°C to +70°C .............................................................................................. Dice
SP231AEP ................................................................................... –40°C to +85°C ..................................................................... 14–pin Plastic DIP
SP231AET ................................................................................... –40°C to +85°C .............................................................................. 16–pin SOIC
SP232ACN..................................................................................... 0°C to +70°C ........................................................................... 16–pin N–SOIC
SP232ACP ..................................................................................... 0°C to +70°C ....................................................................... 16–pin Plastic DIP
SP232ACT ..................................................................................... 0°C to +70°C ................................................................................ 16–pin SOIC
SP232ACX ..................................................................................... 0°C to +70°C .............................................................................................. Dice
SP232AEN ................................................................................... –40°C to +85°C .......................................................................... 16–pin N-SOIC
SP232AEP ................................................................................... –40°C to +85°C ..................................................................... 16–pin Plastic DIP
SP232AET ................................................................................... –40°C to +85°C .............................................................................. 16–pin SOIC
SP233ACP ..................................................................................... 0°C to +70°C ....................................................................... 20–pin Plastic DIP
SP233ACT ..................................................................................... 0°C to +70°C ................................................................................ 20–pin SOIC
SP233AEP ................................................................................... –40°C to +85°C ..................................................................... 20–pin Plastic DIP
SP233AET ................................................................................... –40°C to +85°C .............................................................................. 20–pin SOIC
SP310ACP ..................................................................................... 0°C to +70°C ....................................................................... 18–pin Plastic DIP
SP310ACT ..................................................................................... 0°C to +70°C ................................................................................ 18–pin SOIC
SP310ACX ..................................................................................... 0°C to +70°C .............................................................................................. Dice
SP310AEP ................................................................................... –40°C to +85°C ..................................................................... 18–pin Plastic DIP
SP310AET ................................................................................... –40°C to +85°C .............................................................................. 18–pin SOIC
SP312ACP ..................................................................................... 0°C to +70°C ....................................................................... 18–pin Plastic DIP
SP312ACT ..................................................................................... 0°C to +70°C ................................................................................ 18–pin SOIC
SP312ACX ..................................................................................... 0°C to +70°C .............................................................................................. Dice
SP312AEP ................................................................................... –40°C to +85°C ..................................................................... 18–pin Plastic DIP
SP312AET ................................................................................... –40°C to +85°C .............................................................................. 18–pin SOIC
Please consult the factory for pricing and availability on a Tape-On-Reel option.
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation
Headquarters and
Sales Office
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (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 the
application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.