SP504 Datasheet, PDF (18/32 Pages) Sipex Corporation – WAN Multi-Mode Serial Transceiver

may represent other interface modes not
specified (consult the factory for more in-
formation). The drivers are controlled with
the data bits labeled TDEC₃–TDEC₀. All of
the drivers can be put into tri-state mode
by writing 0000 to the driver decode switch.
The three drivers TxD, ST and TxC, have a
150Ω pull-down resistor to ground connected
at the (b) output. This resistor is part of the
V.35 driver circuitry and should be connected
when in V.35 mode. Tri-state is possible for
all drivers in RS-232 mode. The receivers
are controlled with data bits RDEC₃–RDEC₀;
the code 0000 written to the receivers will
place the outputs into tri-state mode. The
0000 decoder word will override the enable
control line for the one receiver (SCT).
Using the V.35_STAT Pin
The SP504 includes a V.35 status pin where
the V35_STAT pin (pin 18) is a logic HIGH
("1") when the decoder is set to V.35 mode.
The pin is a logic LOW ("0") when in all other
modes including tri-state (decoder set at
"0000"). Pin 18 allows the user to easily
add FET switches or solid state relays to
connect the external 150Ω resistor for V.35
operation. V35_STAT can be connected to
the gate of the FET switches or the control
of the relays so that the 150Ω resistors are
connected to the non-inverting output of the
three V.35 drivers. The output current of the
V35_STAT pin is that of a typical TTL load
of –3.2mA. The electrical specifications
are similar to the SP504 receiver outputs.
This feature would reduce additional logic
required by older traditional methods.
NET1/NET2 Testing and Compliancy
Many system designers are required to certify
their system for use in the European public
network. Electrical testing is performed in
adherence to the NET (Norme Européenne
de Télécommunication) which specifies the
ITU Series V specifications. The SP504
adheres to all the required physical layer
testing for NET1 and NET2. Consult factory
for details.
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
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