SP303 Datasheet, PDF (6/8 Pages) Sipex Corporation – RS232/AppleTalk TM Serial Transceiver

SP303CT is usually connected to the outside
world, it is suggested that the user place tran-
sient voltage suppression devices on each of the
I/O lines to ensure up to ±25kV ESD protection.
While the part is programmed for RS-232 mode,
the drivers and receivers can operate up to
200kbps. The RS-232 receiver inputs are ca-
pable of receiving signals up to ±30V. The
Macintosh™ AppleTalk™ mode inputs and
outputs are protected to guard against the situa-
tion where an RS-232 cable is connected to the
port while it is configured for AppleTalk™
mode.
APPLICATION EXAMPLE
MACINTOSH™ APPLETALK™ SERIAL
INTERFACE
Figure 4 shows the SP303CT programmed for
Macintosh™ AppleTalk™ operating mode. In
this mode the SP303CT offers one differential
driver used for transmitting data, one differen-
tial receiver used for receiving data, one single–
ended, non–inverting receiver used to receive a
handshake signal, and one single–ended invert-
ing driver used to transmit a handshake signal.
The differential driver used for transmitting
data can be put into tri–state mode by bringing
the TxEN line high; a low on this pin will enable
the driver output. This function only applies to
TXD
RTS
DCD
DSR
RXD
CTS
DTR
SUPPLY
+5V +12V –12V
28 1 15
VCC VDD VEE
23
T1
6
RFI FILTER
24
T2
16
R4
27
R2
26 ^SP303
R1
5 _{RFI FILTER}
13 _{RFI FILTER}
2 _{RFI FILTER}
3 _{RFI FILTER}
17
R3
20
T3
12 _{RFI FILTER}
9 _{RFI FILTER}
TXD
RTS
DCD
DSR
RXD
CTS
DTR
19
T4
10
14
GND
SELECT
AB
7
8
876
5
43
21
TXD
RTS
DCD
DSR
RXD
CTS
DTR
SUPPLY
+5V +12V –12V
28 1 15
VCC VDD VEE
23
T1
6
RFI FILTER
24
T2
16
R4
27
R2
26 ^SP303
R1
5 _{RFI FILTER}
13 _{RFI FILTER}
2 _{RFI FILTER}
3 _{RFI FILTER}
17
R3
20
T3
12 _{RFI FILTER}
9 _{RFI FILTER}
TXD
RTS
DCD
DSR
RXD
CTS
DTR
19
T4
10
14
GND
SELECT
AB
7
8
876
5
43
21
Figure 3. RS-232 Interface.
74
Corporation
SIGNAL PROCESSING EXCELLENCE