SP502 Datasheet, PDF (12/32 Pages) Sipex Corporation – Multi-Mode Serial Transceiver

can operate up to 120kbps. The RS-232 drivers
are used in RS-232 mode for all signals, and also
in V.35 mode where they are used as the control
line signals.
The RS-423 drivers output a minimum of ±3.6V
level single–ended signals (with 450Ω loading)
and can operate up to 120kbps. Open circuit
V_OL and V_OH measurements may exceed the
±6V limitation of RS-423. The RS-423 drivers
are used in RS-449 and EIA-530 modes as RL
and LL outputs.
The third type of driver supports RS-485, which
is a differential signal that can maintain ±1.5V
differential output levels with a worst case load
of 54Ω. The signal levels and drive capability of
the RS-485 drivers allow the drivers to also
support RS-422 requirements of ±2V differen-
tial output levels with 100Ω loads. The RS-422
drivers are used in RS-449 and EIA-530 modes
as clock, data, and some control line signals.
The RS-485–type drivers are also used in the
V.35 mode. V.35 levels require ±0.55V signals
with a load of 100Ω. In order to meet the voltage
requirements of V.35, external series resistors
with source impedance termination resistors
must be implemented to voltage divide the driver
outputs from 0 to +5V to 0 to +0.55V. Figure 6
shows the values of the resistor network and
how to connect them. The termination network
also achieves the 50Ω to 150Ω source imped-
ance for V.35. For applications that require
V.11 signals for clock and data instead of V.35
levels, omit the external termination networks.
All of the differential drivers, RS-485, RS-422,
and V.35 can operate up to 5Mbps.
Receivers
The SP502 is equipped with seven (7) receivers
which can be programmed in six (6) different
modes of operation. One of the seven (7) receiv-
ers (RxT) is part of a half-duplex channel, which
means its inputs are shared with a driver
output, as shown in the Mode Diagrams. The
RxT receiver has its inputs internally connected
to the TT(a) and TT(b) pins. The select pin
labeled ST/TT enables either the TT-driver or
the ST-driver, but it does not disable the re-
ceiver. The RxT receiver is always connected to
the TT(a) and TT(b) pins. Any signal that is
received or transmitted on TT(a) and TT(b) will
trigger a TTL-output at the RxT pin.
Control for the mode selection is done via a 4–
bit control word that is independent from the
driver control word. The coding for the drivers
and receivers is identical. Therefore, if the modes
for the drivers and receivers are supposed to be
identical in the application, the control lines can
be tied together.
Like the drivers, the receivers are pre-arranged
for the specific requirements of the interface. As
the operating mode of the receivers is changed,
Pin Label
RDEC₃–RDEC₀
RD(a)
RD(b)
RT(a)
RT(b)
CS(a)
CS(b)
DM(a)
DM(b)
RR(a)
RR(b)
IC(a)
IC(b)
SCT(a)
SCT(b)
Mode:
0000
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
RS-232
0010
RS-232
15kΩ to GND
RS-232
15kΩ to GND
RS-232
15kΩ to GND
RS-232
15kΩ to GND
RS-232
15kΩ to GND
RS-232
15kΩ to GND
RS-232
15kΩ to GND
V.35
1110
V.35–
V.35+
V.35–
V.35+
RS-232
15kΩ to GND
RS-232
15kΩ to GND
RS-232
15kΩ to GND
RS-232
15kΩ to GND
V.35–
V.35+
RS-422
0100
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
*TT(a) and TT(b) can be programmed as driver outputs or receiver inputs.
Table 2. SP502 Receivers
RS-485
0101
RS-485–
RS-485+
RS-485–
RS-485+
RS-485–
RS-485+
RS-485–
RS-485+
RS-485–
RS-485+
RS-485–
RS-485+
RS-485–
RS-485+
RS-449
1100
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-423
15kΩ to GND
RS-422–
RS-422+
EIA-530
1101
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-422–
RS-422+
RS-423
15kΩ to GND
RS-422–
RS-422+
Rev. 7/21/03
SP502 Multi-Mode Serial Transceiver
12
© Copyright 2003 Sipex Corporation