SP504EB datasheet(3/18 Pages) SIPEX

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504/505AppNote/03

New SP504/505 Evaluation Board

Fuse

At the upper right-hand side of the board, just

below the DB-25 connector, is a location for a

fuse. There must either be a fuse, a low value

resistor (1 to 10 ohms) or a jumper wire installed

at this location. A one amp fuse is recommended.

V35_STAT

As mentioned previously, the SP504 device has

a TTL output labled V35_STAT. When the

SP504 is configured to V.35 mode, this pin

provides a high level TTL output. In all other

modes, this pin provides a low level TTL output.

The V35_STAT output is used to control FET

switches which switch 150 ohm V.35 termina-

tion resistors in or out of the SP504 circuit

configuration. This feature is labeled on the

SP50x Evaluation Board but is not used. The

rocker switch for V35_STAT must be in the OFF

position (rocker down) when using SP504 board.

USING THE EVALUATION BOARD

On the bottom righ-hand side of the evaluation

board are two pins identified as GND and V

CC.

Connect this GND to the power supply ground.

Connect V

CC to a +5 volt DC power supply.

If possible, limit the supply current to 0.5-1.0

Amp. Do not switch power on when connecting

power to the evaluation board.

All Drivers Active with Single TTL input

SP504

On the right-hand side of the evaluation board,

connect jumper wires between all seven driver

inputs (TxC, TxD, DTR, RTS, LL, RL, and ST)

to each of the corresponding TTL pin on the right

hand side. Next, configure the mode selection to

the desired mode using TDEC3-TDEC0 on the

right-hand DIP switch and RDEC3-RDEC0 on

the left-hand DIP switch if the SP504 is used.

Connect a system clock or signal generator with

a TTL-level output and a frequency within the

acceptable range of the driver under test to any of

the TTL pins. The common bus will route the

signal to each driver with a jumper installed to

the TTL bus. Ensure that /STEN and /TTEN

enable switches on the left-hand DIP switch

have been set to low position (rocker down) to

enable the drivers. Once the power is on and the

driver inputs receive a signal, the driver outputs

can be analyzed with a oscilloscope or digital

multi-meter.

The mode selection can be

performed at any time using the TDEC and

RDEC positions on the DIP switches.

SP505

This is similar to the SP505 except that the

RDEC positions on the left DIP switch are now

low-active enable lines for the ST, DTR, RTS,

and LL drivers. The V35_STAT is now the low-

active RL driver enable pin.

DRIVER/RECEIVER LOOPBACK

SP504

This example uses the ST driver looped back into

the SCT receiver. First, configure the mode

select for the desired mode using RDEC3-RDEC0

on the left-hand DIP switch and TDEC3-TDEC0

on the right-hand DIP switch. Connect a jumper

wire between an ST(a) pin and an SCT(a) pin.

If your mode select is for a differential driver/

receiver, then also connect a jumper wire be-

tween an ST(b) pin and an SCT(b) pin. Next,

connect a signal generator to the ST pin.

The signal generator output must be a TTL-level

output at a frequency within the acceptable range

of the driver mode under test. Set /STEN to logic

low (rocker down) and SCTEN to logic high

(rocker up). The driver outputs are connected

back to the receiver inputs so that driver input to

receiver output delays can be examined. This

configuration is similar for the other drivers.

SP505

The same approach for the SP504 above can be

applied for the SP505. However, the SP505 can

be programmed internally for loopback. DEC

to DEC

3 should be configured as "1010", respec-

tively for a single ended loopback. DEC

0 to

DEC

3 should be configured as "1011", respec-

tively for a differential loopback.

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