Applications Information
Termination Circuitry
The SP322 is designed for serial port applica-
tions needing V.11 and V.35 transceivers. The
SP322 supports a variety of physical layer
protocols such as EIA-530, EIA-530A, RS-449,
and V.36 where V.11 transceivers are used for
clockanddatasignals. Theterminationresistors
are recommended for crosstalk and reflections
elimination under higher speed operation.
Internalterminationsolvesmanyheadachesand
configuration hassles with implementing V.11
and V.35. The SP322 provides a simple, low-
cost solution for the clock and data lines for
synchronousserialports. Thehandshakinglines
such as CTS, DTR, etc. can be implemented
using discrete RS-422 or RS-232 transceivers,
depending on the mode supported. Sipex
supplies either differential (V.11) or single-
ended (V.28) discrete transceiver products
to mate with the SP322.
Unique to Sipex, the SP322 provides internal
resistor networks for V.35 as well as the cable
termination for V.11. The resistor network for
the V.35 receivers are configured as a typical
V.35 receiver using two 51Ω resistors in series
tiedtotheAandBinputswitha124Ωcenter-tap
resistor to ground. The network is internally
switched on during V.35 mode (V.11/V.35 =
V
CC) using high performance, low rON transis-
tors. Thetransistorscanoperateefficientlyover
+7V to -7V, and can tolerate over +10V to -10V
without damage. This termination provides the
proper V.35 receiver input impedance of 100Ω
and short-circuit impedance at 2V of 150Ω with
10% accuracy.
The configuration for the V.11 receiver input
resistor network is similar to the V.35 network
except that the 124Ω resistor is disconnected
(V.11/V.35 = 0V). A series resistor is also
added increase the input impedance to over
120Ω for the V.11 cable termination. The
minimumresistancepertheITUV.11specifica-
tion is 100Ω. The V.11 termination can be
switched off using the V.11_TERM pin. For a
terminated V.11 receiver, this pin is at a logic
"1". A logic "0" will inform the switches to
disconnect the V.11 termination.
Shutdown
The SP322 includes a shutdown pin (SD) which
disables the charge pump and all power con-
suming circuitry to provide low ICC. A logic "1"
to the SD pin will shut down the SP322 where it
will draw less than 20µA of current.
NET1/2 European Compliancy
As with all of Sipex's previous multi-protocol
transceiver ICs, the SP322 drivers and receivers
have been designed to meet all electrical
specifications for ITU V.11 and V.35.
Furthermore, it is internally tested and will pass
the NET1/2 physical layer testing requirements.
Please note that although the SP322 adheres to
NET1/2 testing, any complex or unusual
configuration should be double-checked to
ensure NET compliance. Consult factory for
details.
SP322DS/06
Rev. 7/9/03
SP322 V.11/V.35 Serial Transceiver
SP322 V.11/V.35 Serial Transceiver
© Copyright 1997 Sipex Corporation
© Copyright 2003 Sipex Corporation
11
SIPEX [ SIPEX CORPORATION ]
