SP3223U Datasheet, PDF (10/24 Pages) Sipex Corporation – High Speed Intelligent +3.0V to +5.5V RS-232 Transceivers

DESCRIPTION
The SP3223U and SP3243U transceivers
meet the EIA/TIA-232 and ITU-T V.28/V.24
communication protocols and can be
implemented in battery-powered, portable, or
hand-held applications such as notebook or
palmtop computers. The SP3223U and SP3243U
devices 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 SP3223U and SP3243U devices can operate
at a data rate of 1000kbps fully loaded.
The SP3223U is a 2-driver/2-receiver device,
and the SP3243U is a 3-driver/5-receiver device,
ideal for portable or hand-held applications. The
SP3243U 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 µC
+
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 ^T3^IN
26
VCC
V+ ²⁷
+
C3 0.1µF
SP3243U _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
R₁IN ₄
18 ^R2^OUT
17 ^R3^OUT
5KΩ
R₂IN ₅
5KΩ
R₃IN ₆
16 ^R4^OUT
5KΩ
R₄IN ₇
15 ^R5^OUT
22
SHUTDOWN
23 _ONLINE
5KΩ
R₅IN ₈
5KΩ
21 _STATUS
GND
25
RS-232
INPUTS
RESET
µP
Supervisor
VIN
IC
The SP3223U and SP3243U series is an ideal
choice for power sensitive designs. The SP3223U
and SP3243U 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 conditions, the internal
charge pump and the drivers will be shut down.
Otherwise, the system automatically comes
online. This feature allows design engineers to
address power saving concerns
without major design changes.
THEORY OF OPERATION
The SP3223U and SP3243U 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-232-F and all
previous RS-232 versions. Unused drivers in-
puts should be connected to GND or V_CC.
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 16. Interface Circuitry Controlled by Micropro-
cessor Supervisory Circuit
Date: 5/25/04
SP3223U/3243U +3.0V to +5.5V RS-232 Transceivers
10
© Copyright 2004 Sipex Corporation