SP2209E Datasheet, PDF (7/15 Pages) Sipex Corporation – High ESD Dual Port RS-232 Transceiver

DESCRIPTION
The SP2209E device is a rugged, high ESD,
complete dual RS-232 port integrated onto a
single integrated circuit. Six drivers and ten
receivers provide a dual port solution fully
meeting the EIA/TIA-232 and ITU-T V.28/V.24
communication protocols and can be
implemented in applications such as personal
desktop computers and workstations. Refer to
Figure 2 for a typical operating circuit.
Features include high transmission rates, low
power consumption, space saving package
dimensions, and compatibility with the EU
directive on electromagnetic compatibility.
EM compatibility includes protection against
radiated and conducted interference including
high levels of electrostatic discharge. This device
is ideal for operation in electrically harsh
environments or where RS-232 cables are
frequently being plugged and unplugged. This
device is also immune to high RF field strengths
without special shielding precautions. Emissions
are also controlled to within very strict limits.
The SP2209E device features the inverter
portion of Sipex's proprietary and patented
(U.S. 5,306,954) on-board charge pump
circuitry that generates a -9V voltage level from
a single +12V power supply. The SP2209E
device can operate at data rates of at least
460kbps fully loaded.
Its low power CMOS operation makes the
SP2209E device an ideal choice for power
sensitive designs. The SP2209E device has two
receivers, one for each RS-232 port, that
remains active in the standby mode to allow the
monitoring of peripheral devices while the rest
of the system is in a power-saving standby
mode. This allows the SP2209E device to wake
up the entire system when any communication
is initiated in peripheral devices. The SP2209E
device has a low standby current of 100µA.
THEORY OF OPERATION
The SP2209E device is made up of four
basic circuit blocks: 1. Drivers, 2. Receivers,
3. the Sipex proprietary charge pump, and
4. Standby circuitry.
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. With V =
DD
+12V, the typical RS-232 output voltage swing
is +9V with no load and +5V minimum fully
loaded. Unused driver input may be left
unconnected with an internal pull-up resistor
pulling the inputs high forcing the driver outputs
into a low state. The driver outputs are protected
against infinite short-circuits to ground without
degradation in reliability. These drivers comply
with the EIA-TIA-232F and all previous
RS-232 versions.
The drivers typically can operate at a minimum
data rate of 460kbps fully loaded with 3KΩ in
parallel with 1000pF, ensuring compatibility
with PC-to-PC communication software. The
SP2209E device is ideal for the new generation
modem standards which require data rates greater
than 460kbps. Refer to Figures 3 and 5 for driver
propagation delay test circuit and waveforms,
respectively.
Receivers
The receivers convert EIA/TIA-232 levels to
TTL or CMOS logic output levels. Should an
unused receiver input be left unconnected, an
internal 5kΩ pulldown resistor to ground will
commit the output of the receiver to a HIGH
state. Receiver inputs are also protected
against overvoltages of up to +15V. Refer to
Figures 4 and 6 for receiver propagation delay test
circuit and waveforms, respectively.
SP2209E DS/06
SP2209E High ESD Dual Port RS-232 Transceivers
7
© Copyright 2000 Sipex Corporation