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
suppliedontape-on-reel,aswellaspartsscreened
to MIL-M-38510.
FEATURES…
The Sipex SP231A, SP232A and SP233A are
enhanced versions of the Sipex SP231, SP232
andSP233RS-232linedrivers/receivers.Theyarepin-
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
longerandmoreflexiblecableconfigurations.Easeof
useenhancementsincludesmaller,0.1µFchargepump
capacitors, enhanced ESD protection, low power
dissipation and overall ruggedized construction for
commercial environments.
THEORY OF OPERATION
The SP231A, SP232A, SP233A, SP310A and
SP312Adevicesaremadeupofthreebasiccircuit
blocks–1)adriver/transmitter,2)areceiverand3)
a charge pump. Each block is described below.
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 specifica-
tions. 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.
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
theinputlogiclevels. TypicallytheRS-232output
voltage swing is ±9V. Even under worst case
loading conditions of 3kOhms and 2500pF, the
outputisguaranteedtobe±5V,whichisconsistent
with the RS-232 standard specifications. The
transmitter outputs are protected against infinite
short-circuits to ground without degradation in
reliability.
The SP310A provides identical features as the
SP232A. The SP310A has a single control line
whichsimultaneouslyshutsdowntheinternalDC/
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 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)].
The SP231A is available in 14-pin plastic DIP,
CERDIP and 16-pin SOIC packages for opera-
tion over commercial, industrial and military
temperature ranges. The SP232A is available
in 16-pin plastic DIP, SOIC and CERDIP
S1
S2
S3
S4
S1
S2
S3
S4
V
V+ = 2V
CC
CC
V+
FROM
GND
+
+
+
+
C1
C3
C2
C4
VOLTAGE DOUBLER
V
CC
GND
GND
V- = -(V+)
INTERNAL
OSCILLATOR
INTERNAL
OSCILLATOR
Figure 1. Charge Pump Voltage Doubler
Figure 2. Charge Pump Voltage Inverter
SP231ADS/01
SP231A Enhanced RS-232 Line Drivers/Receivers
© Copyright 2000 Sipex Corporation
4
SIPEX [ SIPEX CORPORATION ]
