SP504EB datasheet(2/18 Pages) SIPEX

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504/505 AppNote/03

New SP504/505 Evaluation Board

BOARD LAYOUT

I/O Pinouts

The SP504/SP505 Evaluation Board has been

designed to easily and conveniently provide

access to all inputs and outputs to the device

under test. Position the board with the DB-25

connector at the top and the DIP switches at the

bottom. From this orientation, all driver inputs

and outputs are located on the right-hand side of

the board while all receiver inputs and outputs

are located on the left-hand side of the board.

The access pins are arranged in groups of eight

pins for each driver and seven pins for each

receiver. Starting at the "TxC" driver located at

the upper right-hand corner of the board, the first

two rows of pins are TT(a). These are the TxC

driver output TT(a) connections. There are two

probe pins to accomodate loads, multiple test

clips, etc. Below the TT(a) pins are two TT(b)

pins. The last two pins below the TT(b) pins are

ground pins.

Located in front of the TT(a), TT(b) and ground

pins are two pins marked TxC and TTL.

The TxC pin is the input to the TxC driver while

the TTL pin is connected to a common bus. This

common TTL bus provides a convenient way to

connect some or all driver inputs to a common

TTL signal.

The remaining six drivers are arranged similar to

the TxC driver.

The receivers are laid out similar to the drivers,

but on the opposite side of the board. Starting at

the upper left-hand corner of the evaluation

board are two pins on the same row marked

CS(a). These are the CTS receiver input CS(a)

connections. Below the CS(a) pins are two CS(b)

pins. Below the CS(b) pins are two ground pins.

In front of the six CS(a), CS(b) and ground pins

is a single pin marked CTS. This is the TTL

output from the CTS receiver.

Again, the remaining receivers are similarly laid

out.

DIP Switches

At the bottom of the evaluation board are two

DIP switches. A switch placed in an "up" posi-

tion configures a logic HIGH while a "down"

position configures a logic LOW. The right-

hand DIP switch is used to configure the driver

and receiver mode select for the SP505 device or

just the driver mode select for the SP504 device.

These four mode select switches are marked

TDEC3-TDEC0. The right-hand DIP switch also

controls the SCT receiver enable line, SCTEN,

and the decoder latch control, LATCH, in the

SP505. Please note that logic LOW is off (rocker

down) as labeled on the DIP switch, not high or

low as labeled on the evaluation board.

The left-hand DIP switch is used to configure the

SP504 receiver mode select pins RDEC3-

RDEC0. But internally within the SP505, the

receiver and driver mode select lines are grouped

together as common select lines DEC3-DEC0

which are identified on the evaluation board as

TDEC3-TDEC0 on the right-hand DIP switch.

Thus, on the left-hand DIP switch for the SP505

device, the RDEC3-RDEC0 positions are

instead used to control the individual driver

tri-state controls,/RLEN, /LLEN, /RSEN,

/TREN & /SDEN.

R13

On the left-center position of the evaluation

board, immediately to the left of the SP504 or

SP505 device, is a column of resistors. There are

eleven resistors required for the SP504 device on

the evaluation board. Therefore, there should be

one open position marked for resistor R13 only

for SP505. If the evaluation board is being used

for the SP505, then this position must be fitted

with a 500 ohm 1% resistor. This R13 is the pull-

down resistor for the /RLEN control line which

is a TTL input. The R13 is left open for the SP504

because pin 18 is a TTL output (V35_STAT) on

the SP504.

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