XR-T3588-89ES

XR-T3588/89

Evaluation System

Rev. 1.00

5

OVERVIEW

This unit is a 4.5 by 5.0 inch circuit board that simplifies the

evaluation of the XR-T3588 line driver and the XR-T3589

line receiver devices in a CCITT V.35 application. Its

features include dip switch selection of channel

power-down options, and provisions for applying the

ground potential offset voltage specified by the V.35 test

procedure to the receiver inputs.

Figure 1., Figure 2. and

Table 3. show the demo board component layout, circuit

diagram and list of components respectively.

POWER REQUIREMENTS

Supply voltages of +5.0V

Both power sources should be well-regulated, and each

must be capable of supplying 250mA minimum. During

normal operation jumper E-1 must be installed, and

nothing is connected to the banana jack labeled OFFSET.

XR-T3588 DIGITAL INPUT AND XR-T3589 DIGITAL

OUTPUT CONNECTIONS

The TTL compatible transmitter inputs are the BNC

connectors mounted on the left side of the board that are

labeled TX1IN, TX2IN and TX3IN.

Provisions are

included for installing input termination resistors R1, R2,

and R3 if required.

These resistors (50 or 75

Ω) are

needed only if a pulse generator with a low impedance

output and a fast rise time is used as a test signal source.

They are not required for TTL signals applied to the board

through short cables.

Likewise, the TTL compatible receiver outputs are the

BNC connectors labeled RX1OUT, RX2OUT and

RX3OUT.

XR-T3588 LINE OUTPUT AND XR-T3589 LINE INPUT

CONNECTIONS

The line connections are made to the six RJ-11

connectors or to the corresponding test point pairs that

are located on the right side of the board. The RJ-11s are

for connecting twisted pair cables, and the test points

provide a convenient means for viewing the output and

input signals differentially on an oscilloscope. From top to

bottom, the three transmitter outputs are labeled

TX1OUT, TX2OUT, and TX3OUT, and the three receiver

inputs are labeled RX1IN, RX2IN, and RX3IN. Note that

connectors are wired so that the “A” and “B” XR-T3588

output pins and the “A” and “B” XR-T3589 input pins go to

the same pin numbers on the RJ-11 connectors.

Therefore, a test cable must be wired in the same manner

to prevent a data inversion between the transmitter digital

input and the receiver digital output. (Telephone cables

typically contain a “twist” between modular connectors,

and will therefore give a data inversion.)

TRANSMITTER AND RECEIVER POWER-DOWN

The four-position DIP switch located in the center of the

board selects the logic state applied to the transmitter and

receiver channel enable pins.

The top two sections

labeled TX, and the bottom two sections labeled RX are

for the XR-T3588 and XR-T3589 respectively. Table 1.

and

Table 2. show the powering options. Note that when

a DIP switch section is “OFF,” a logic 1 is applied to the

corresponding IC pin.

XR-T3588

TX Switch Sections

Transmitter

SEL A

SEL B

1, 2, 3, On

Off

Off

1, 2, On

Off

On

1 On

On

Off

All Off

On

On

Table 1. XR-T3588 Transmitter Selection