SP3223E_06 Datasheet, PDF (9/23 Pages) Sipex Corporation – Intelligent +3.0V to +5.5V RS-232 Transceivers

DESCRIPTION
The SP3223 is a 2-driver/2-receiver device
ideal for portable or handheld applications.
The SP3223 transceivers meet the EIA/TIA-232
and ITU-T V.28/V.24 communication protocols
and can be implemented in battery-powered,
portable, or handheld applications such as note-
book or handheld computers. The SP3223 de-
vices feature Sipex's proprietary and patented
(U.S.-- 5,306,954) on-board charge pump cir-
cuitry that generates ±5.5V RS-232 voltage lev-
els from a single +3.0V to +5.5V power supply.
The SP3223 devices operate at this typical data
rate when fully loaded.
The SP3223 series is an ideal choice for power
sensitive designs. Featuring AUTO ON-LINE^®
circuitry, the SP3223 reduces the power supply
drain to a 1µA supply current. In many portable
or handheld applications, an RS-232 cable can
be disconnected or a connected peripheral can be
turned off. Under these conditions, the internal
charge pump and the drivers will be shut down.
+3V to +5V
+
C5 0.1µF
+
C1 0.1µF
2 _C1+
4 C1-
+
C2 0.1µF
5 C2+
6 C2-
13 ^T1^IN
TTL/CMOS
INPUTS 12 T₂IN
19
VCC
V+ ³
+
C3 0.1µF
SP3223
V- ⁷
C4 0.1µF
+
T₁OUT ₁₇
T₂OUT ₈
RS-232
OUTPUTS
UART
or
Serial µC
15 ^R1^OUT
TTL/CMOS
OUTPUTS
10 ^R2^OUT
R₁IN ₁₆
5KΩ
R₂IN ₉
5KΩ
VCC
RESET
µP
Supervisor
VIN
IC
1 _EN
20 _SHUTDOWN
14 _ONLINE
11 _STATUS
GND
18
RS-232
INPUTS
Figure 13. Interface Circuitry Controlled by Micropro-
cessor Supervisory Circuit
Otherwise, the system automatically comes
online. This feature allows design engineers to
address power saving concerns without major
design changes.
THEORY OF OPERATION
The SP3223 series is made up of four basic
circuit blocks:
1. Drivers, 2. Receivers, 3. the Sipex proprietary
charge pump, and 4. AUTO ON-LINE^® cir-
cuitry.
Drivers
The drivers are inverting level transmitters that
convert TTL or CMOS logic levels to 5.0V EIA/
TIA-232 levels with an inverted sense relative to
the input logic levels. Typically, the RS-232
output voltage swing is +5.4V with no load and
+5V minimum fully loaded. 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. Unused driver inputs
should be connected to GND or V_CC.
The drivers can guarantee output data rates fully
loaded with 3KΩ in parallel with 1000pF,
(SP3223EU, C_L= 250pF) ensuring compatibility
with PC-to-PC communication software.
The slew rate of the driver output on the E and EB
versions is internally limited to a maximum of
30V/µs in order to meet the EIA standards (EIA
RS-232D 2.1.7, Paragraph 5). The Slew Rate of
H and U versions is not limited to enable higher
speed data tranfers. The transition of the loaded
output from HIGH to LOW also meets the mono-
tonicity requirements of the standard.
Figure 12 shows a loopback test circuit used to
test the RS-232 Drivers. Figure 13 shows the test
results where one driver was active at 235Kbps
and all drivers are loaded with an RS-232 re-
ceiver in parallel with a 1000pF capacitor. RS-
232 data transmission rate of 120Kbps to 1Mbps.
provide compatibility with designs in personal
computer peripherals and LAN applications.
Date: 10/06/06
SP3223 +3.0V to +5.5V RS-232 Transceivers
9
© Copyright 2006 Sipex Corporation