SP3508EB Datasheet, PDF (9/13 Pages) Sipex Corporation – Evaluation Board Manual

USING THE EVALUATION BOARD: Continued
Driver/Receiver Remote Loopback
The following example uses the ST driver
looped back into the TxC receiver. Use the
3 bit decoder to configure the SP3508 for the
desired protocol. Connect a jumper cable
between the ST(a) pin and the TxC(a) pin. If
your mode select is set for a differential
driver/receiver, then also connect a jumper
cable between the ST(b) pin and the TxC(b)
pin. The next step is to connect a signal
generator to the ST input pin through BNC
input connector. The signal generator out-
put must be a TTL-level output at a fre-
quency within the acceptable range of the
driver mode under test. Be sure that the
jumper settings of STEN signal and TxCEN
signal are set to enable the ST driver and
TxC receiver. The driver outputs are now
connected back to the receiver inputs so
that the driver input to receiver output can be
examined. This configuration is similar for
all other drivers.
Driver/Receiver Local Loopback
The SP3508 has the ability to provide an
internal loopback. This feature is invoked by
a logic “0” on the /LOOPBACK pin. The
driver input and receiver output characteris-
tics adhere to the appropriate specifications
outlined in the datasheet under loopback
conditions. The /LOOPBACK pin has an
internal pull-up resistor so that the SP3508
defaults to normal operation during power-
up or if the pin is left floating.
DCE DTE selectable configuration
• Configure the decoder for the desired
mode.
• The SP3508 evaluation board has jumper
setup to allow for the evaluation of a select-
able DCE DTE configuration.
• Set the STEN and RRCEN to Logic “0”.
This will disable the ST and RRC driver
outputs. (Refer to the Jumper Setting Guide
in the next section)
• Set the /TxCEN and /RRTEN to Logic “1”.
This will disable the TxC and RRT receiver
inputs. (Refer to the Jumper Setting Guide in
the next section)
• Use an external wire to tie the ST driver
outputs to the TxC Receiver inputs.
• Use an external wire to tie the RRC driver
outputs to the RRT receiver inputs.
• To enable a DTE configuration, set the
STEN and RRCEN to Logic “1”. Be sure the
TxC and RRT receivers are disabled by
setting the /TxCEN and /RRTEN to Logic
“1”. (Refer to the Jumper Setting Guide in
the next section)
• To enable a DCE configuration, set the /
TxCEN and /RRTEN to Logic “0”. Be sure to
disable the ST and RRC driver outputs by
setting the STEN and RRCEN to Logic “0”.
(Refer to the Jumper Setting Guide in the
next section)
System Level Evaluation
• Use DB-25 Connector if the evaluation
board is configured as a DTE for EIA-530
pinout. In order to connect to other DCE
equipment or network analyzers ( i.e. the
TTC Firebird 6000A), the RxC receiver out-
put must be looped back to the TxCE driver
input. The RxD output can also be looped
back to the TxD input.
• If connecting the evaluation board to a
microcontroller such as the Motorola
MC68360, jumper wires of the driver inputs
and receiver outputs must connect to the
uC’s appropriate pins.
Rev. 8/28/03
SP3508 Evaluation Board Manual
9
© Copyright 2003 Sipex Corporation