SP3223EB Datasheet, PDF (10/25 Pages) Sipex Corporation – Intelligent +3.0V to +5.5V RS-232 Transceivers

DESCRIPTION
The SP3223EB and SP3243EB transceivers meet
the EIA/TIA-232 and ITU-T V.28/V.24 com-
munication protocols and can be implemented
in battery-powered, portable, or hand-held ap-
plications such as notebook or palmtop comput-
ers. The SP3223EB and SP3243EB devices
feature Sipex's proprietary and patented (U.S.--
5,306,954) on-board charge pump circuitry that
generates ±5.5V RS-232 voltage levels from a
single +3.0V to +5.5V power supply. The
SP3223EB and SP3243EB devices can operate
at a data rate of 250kbps fully loaded.
The SP3223EB is a 2-driver/2-receiver device,
and the SP3243EB is a 3-driver/5-receiver de-
vice ideal for portable or hand-held applications.
The SP3243EB includes one complementary
always-active receiver that can monitor an
external device (such as a modem) in shutdown.
This aids in protecting the UART or serial
controller IC by preventing forward biasing
of the protection diodes where V_CC may be
disconnected.
VCC
UART
or
Serial C
+
C5 0.1µF
28 _C1+
+
C1 0.1µF
24 C1-
+
C2 0.1µF
1 C2+
2 C2-
TxD
14 ^T1^IN
RTS
13 T2IN
DTR
12 T3IN
26
VCC
V+ ²⁷
+
C3 0.1µF
SP3243EB _V- 3
T₁OUT ₉
T₂OUT 10
T₃OUT 11
C4 0.1µF
+
RS-232
OUTPUTS
RxD
CTS
DSR
DCD
RI
VCC
20 ^R2^OUT
19 ^R1^OUT
18 ^R2^OUT
17 ^R3^OUT
16 ^R4^OUT
R₁IN ₄
5KΩ
R₂IN ₅
5KΩ
R₃IN ₆
5KΩ
R₄IN ₇
15 ^R5^OUT
22
SHUTDOWN
23 _ONLINE
5KΩ
R₅IN ₈
5KΩ
21 _STATUS
GND
25
RS-232
INPUTS
RESET
P
Supervisor
VIN
IC
Figure 16. Interface Circuitry Controlled by Micropro-
cessor Supervisory Circuit
The SP3223EB and SP3243EB series is an ideal
choice for power sensitive designs. The
SP3223EB and SP3243EB devices feature
AUTO ON-LINE^® circuitry which reduces the
power supply drain to a 1µA supply current. In
many portable or hand-held applications, an RS-
232 cable can be disconnected or a connected
peripheral can be turned off. Under these condi-
tions, the internal charge pump and the drivers
will be shut down. Otherwise, the system auto-
matically comes online. This feature allows de-
sign engineers to address power saving concerns
without major design changes.
THEORY OF OPERATION
The SP3223EB and SP3243EB series is made up
of four basic circuit blocks:
1. Drivers,
2. Receivers,
3. the Sipex proprietary charge pump, and
4. AUTO ON-LINE^® circuitry.
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 a data rate of 250kbps
fully loaded with 3kΩ in parallel with 1000pF,
ensuring compatibility with PC-to-PC commu-
nication software.
The slew rate of the driver output 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 transition of the loaded
output from HIGH to LOW also meets the
monotonicity requirements of the standard.
Date: 6/2/04
SP3223EB/3243EB +3.0V to +5.5V RS-232 Transceivers
10
© Copyright 2004 Sipex Corporation