FEATURES…
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 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.
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 opera-
tion 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 V
OL
to V
OH
clearly meets the
monotonicity requirements of the standard [EIA
RS-232-D 2.1.7, Paragraphs (1) & (2)].
S1
V
CC
+
S2
GND
C1
S3
V+ = 2V
CC
+
S4
C3
V
CC
S1
V+
S3
GND
+
C2
+
S4
C4
V- = -(V+)
FROM
VOLTAGE DOUBLER
GND
S2
INTERNAL
OSCILLATOR
INTERNAL
OSCILLATOR
Figure 1. Charge Pump Voltage Doubler
SP231ADS/01
Figure 2. Charge Pump Voltage Inverter
SP231A Enhanced RS-232 Line Drivers/Receivers
© Copyright 2000 Sipex Corporation
4
SIPEX [ SIPEX CORPORATION ]
