SP508EB Datasheet, PDF (6/10 Pages) Sipex Corporation – Evaluation Board Manual

USING THE EVALUATION BOARD
Recommended Equipment
• Oscilloscope
• Digital multimeter
• Signal Generator capable of >40MHz
• Communications Analyzer (such as
Firebird 6000)
Parametric Evaluation
Located on the board are two pins identified
as V_CC and SIGNAL GND. Connect V_CC to
a +5V DC supply. If possible limit the supply
current to 0.5 to 1.0 Amps. Be sure to have
power off when connecting the supply to the
board.
SP508 Decoder
The SP508 uses a 3 bit decoder to desig-
nate the protocol selected. There is also a
decoder latch pin available. Table 2 and
Table 3 show the decoder modes for the
driver and receiver. Upon power up the
latch pin needs to be in a transparent state
(logic low or floating) or the SP508 will be in
an unknown state. Note that D0, D1, and D2
set as logic high will put the device shut-
down overriding all individual enable/dis-
able lines and the drivers outputs and re-
ceiver inputs will tri-state. In shutdown
mode the termination resistors also discon-
nect.
Driver Evaluation
Each driver has an internal pull-up so that it
is in a defined state when the input is open.
Connect a system clock or a signal genera-
tor with a TTL-level output and the appropri-
ate frequency within the acceptable range
of the driver under test to driver input you
wish to evaluate. There is an individual
enable line for each driver that can be used
to tri-state the driver. Each enable line has
an internal pull up or pull down insure the
driver is enabled if the enable pin is not
connected or floating. Set the appropriate
DIP switch to the “OFF” position to enable
the driver under test. Once the power is on
and the driver input receives a signal, the
driver outputs can be analyzed with an
oscilloscope or a digital multimeter. Mode
selection can be performed at any time by
changing the state of the DIP switches for
the 3 bit decoder. The appropriate termina-
tion for the driver under test can be added to
driver output and tied to the ground buss.
Receiver Evaluation
The SP508 receivers have internal termina-
tion appropriate for V.35 and RS-422 modes
(refer to the SP508 data sheet for more
detail on the receiver termination). The is
activated when the receiver is set to act as a
V.11 receiver (see Table 3) and the
TERM_OFF pin is logic “0”. Each receiver
has a fail-safe feature than outputs a logic
“1” when the receiver in open, terminated
but open, or shorted together. There is an
individual enable line for each receiver that
can be used to tri-state the driver. Each
enable line has an internal pull up or pull
down to insure the receiver is enabled if the
enable pin is not connected or floating. Set
the appropriate DIP switch to the “OFF”
position to enable the receiver under test. As
with the drivers the mode selection can be
performed at any time after power up by
changing the state of the 3 bit decoder. To
evaluate the receiver the appropriate input
signal needs to be applied. To accomplish
this provide a signal from an external source
or use the SP508 driver output and jumper it
to the receiver input. For single ended re-
ceivers tie the active driver output to the
active receiver input. For differential drivers
tie the “A” driver output to the “A” receiver
input and the “B” driver output to the “B”
receiver input. Using the TTL signal on the
driver input will allow the analysis receiver
levels and timing characteristics. The DIP
switches on the right hand side also provide
a means of evaluating the TxC and RRT
receivers by tying the ST and RRC drivers to
the appropriate receivers eliminating the
need for jumper wires.
rev. 7/7/03
SP508 Evaluation Board Manual
6
© Copyright 2003 Sipex Corporation