SP3222EU Datasheet, PDF (8/20 Pages) Sipex Corporation – 3.3V, 1000 Kbps RS-232 Transceivers

DESCRIPTION
The SP3222EU and SP3232EU are 2 driver/
2receiver devices ideal for portable or hand-
held applications. The SP3222EU features a
1µA shutdown mode that reduces power
consumption and extends battery life in
portable systems. Its receivers remain active
in shutdown mode, allowing external devices
such as modems to be monitored using only 1
µA supply current.
The SP3222EU/3232EU transceivers meet the
EIA/TIA-232 and V.28/V.24 communication
protocols They feature Sipex's proprietary on-
board charge pump circuitry that generates 2 x
V for RS-232 voltage levels from a single
CC
+3.0V to +5.5V power supply. The
SP3222EU/3232EU drivers operate at a
minimum data rate of 1000kbps.
THEORY OF OPERATION
The SP3222EU/3232EU series are made up of
three basic circuit blocks: 1. Drivers, 2.
Receivers, and 3. the Sipex proprietary
charge pump.
Drivers
The drivers are inverting level transmitters that
convert TTL or CMOS logic levels to ±5.0V
EIA/TIA-232 levels inverted relative to the
input logic levels. Typically, the RS-232
output voltage swing is ±5.5V with no load
and at least ±5V minimum fully loaded. The
driver outputs are protected against infinite
short-circuits to ground without degradation in
reliability. Driver outputs will meet EIA/TIA-
562 levels of ±3.7V with supply voltages as
low as 2.7V.
The drivers have a minimum data rate of
1000kbps fully loaded with 3KΩ in
parallel with 250pF, ensuring compatibility
with PC-to-PC communication software.
Figure 11 shows a loopback test circuit used
to the RS-232 drivers. Figure 12 shows the
test results of the loopback circuit with all
drivers active at 250kbps with RS-232 loads in
parallel with 1000pF capacitors. Figure 13
shows the test results where one driver was
active at 1000kbps and all drivers loaded with
an RS-232 receiver in parallel with a 250pF
capacitor.
The SP3222EU driver's output stages are
tristated in shutdown mode. When the power
is off, the SP3222EU device permits the
outputs to be driven up to ±12V. Because the
driver's inputs do not have pull-up resistors,
unused inputs should be connected to V_CC or
GND.
In the shutdown mode, the supply current is
less than 1µA, where SHDN = LOW. When
the SP3222EU device is shut down, the
device's driver outputs are disabled (tri-stated)
and the charge pumps are turned off with V+
pulled down to V_CC and V- pulled to GND.
The time required to exit shutdown is typically
100µs. Connect SHDN to V_CC if the shutdown
mode is not used.
Receivers
The receivers convert EIA/TIA-232 levels to
TTL or CMOS logic output levels. The
SP3222EU receivers have an inverting tri-state
output. Receiver outputs (RxOUT) are tri-
stated when the enable control EN = HIGH.
In the shutdown mode, the receivers can be
active or inactive. EN has no effect on
TxOUT. The truth table logic of the
SP3222EU driver and receiver outputs can be
found in Table 2.
Rev. A Date:12/11/03
SP3222EU/3232EU 3.3V, 1000kbps RS-232 Transceivers
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© Copyright 2003 Sipex Corporation