rev. 7/7/03

SP508 Evaluation Board Manual

© Copyright 2003 Sipex Corporation

6

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

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

USING THE EVALUATION BOARD

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.