SP3508CF datasheet(22/33 Pages) SIPEX

22 / 33 page

Date: 06/14/04

SP3508 Enhanced WAN Multi–Mode Serial Transceiver

The SP3508 contains highly integrated serial

transceivers that offer programmability between

interface modes through software control. The

SP3508 offers the hardware interface modes for

RS-232 (V.28), RS-449/V.36 (V.11 and V.10),

EIA-530 (V.11 and V.10), EIA-530A (V.11 and

V.10), V.35 (V.35 and V.28) and X.21(V.11).

The interface mode selection is done via three

control pins, which can be latched via micropro-

cessor control.

The SP3508 has eight drivers, eight receivers,

and Sipex's patented on-board charge pump

(5,306,954) that is ideally suited for wide area

network connectivity and other multi-protocol

applications. Other features include digital and

line loopback modes, individual enable/disable

control lines for each driver and receiver, fail-

safe when inputs are either open or shorted.

THEORY OF OPERATION

The SP3508 device is made up of

1) the drivers

2) the receivers

3) charge pumps

4) DTE/DCE switching algorithm

5) control logic.

Drivers

The SP3508 has eight enhanced independent

drivers. Control for the mode selection is done

via a three-bit control word into D0, D1, and D2.

The drivers are prearranged such that for each

mode of operation, the relative position and

functionality of the drivers are set up to accom-

modate the selected interface mode. As the

mode of the drivers is changed, the electrical

characteristics will change to support the re-

quired signal levels. The mode of each driver in

the different interface modes that can be se-

lected is shown in Table 1.

There are four basic types of driver circuits –

ITU-T-V.28 (RS-232), ITU-T-V.10 (RS-423),

ITU-T-V.11 (RS-422), and CCITT-V.35.

The V.28 (RS-232) drivers output single-ended

signals with a minimum of +5V (with 3k

Ω &

2500pF loading), and can operate over 120kbps.

Since the SP3508 uses a charge pump to gener-

ate the RS-232 output rails, the driver outputs

will never exceed +10V. The V.28 driver archi-

tecture is similar to Sipex's standard line of RS-

232 transceivers.

The RS-423 (V.10) drivers are also single-ended

signals which produce open circuit VOL and

VOH measurements of +4.0V to +6.0V. When

terminated with a 450

Ω load to ground, the

driver output will not deviate more than 10% of

the open circuit value. This is in compliance of

the ITU V.10 specification. The V.10 (RS-423)

drivers are used in RS-449/V.36, EIA-530, and

EIA-530A modes as Category II signals from

each of their corresponding specifications. The

V.10 driver can transmit over 120Kbps if neces-

sary.

The third type of drivers are V.11 (RS-422)

differential drivers. Due to the nature of differ-

ential signaling, the drivers are more immune to

noise as opposed to single-ended transmission

methods. The advantage is evident over high

speeds and long transmission lines. The strength

of the driver outputs can produce differential

signals that can maintain +2V differential out-

put levels with a load of 100

Ω. The strength

allows the SP3508 differential driver to drive

over long cable lengths with minimal signal

degradation. The V.11 drivers are used in RS-

449, EIA-530, EIA-530A and V.36 modes as

Category I signals which are used for clock and

data. Sipex's new driver design over its prede-

cessors allow the SP3508 to operate over 20Mbps

for differential transmission.

FEATURES

SP3508CF 数据表(PDF) 22 Page - Sipex Corporation

SP3508CF 数据表(HTML) 22 Page - Sipex Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

数据表下载