SP2209E Datasheet, PDF (7/17 Pages) Sipex Corporation – High ESD Dual Port RS-232 Transceiver

The SP2209E device is a rugged, high
ESD, complete dual RS-232 port inte-
grated 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 pro-
tocols and can be implemented in appli-
cations such as personal desktop comput-
ers 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 con-
ducted 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 con-
trolled to within very strict limits.
The SP2209E device features the inverter
portion of Exar'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
up to 460kbps fully loaded.
DESCRIPTION
THEORY OF OPERATION
The SP2209E device is made up of four
basic circuit blocks:
1. Drivers
2. Receivers
3. The Exar proprietary charge pump
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 resis-
tor 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 other previous versions.
The drivers typically 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.
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 initi-
ated in peripheral devices. The SP2209E
device has a low standby current of
100mA.
Receivers
The Receivers convert EIA/TIA-232 levels
to TTL or CMOS logic output levels. Should
an 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 protected against over-
voltages of up to +/-15V. Refer to Figures
4 and 6 for receiver propagation delay test
circuits and waveforms, respectively.
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP2209E_100_071612