SP522CT datasheet(9/22 Pages) SIPEX

9 / 22 page

Rev. 7/10/03

SP522 Multi–Mode Serial Transceivers

FEATURES

The SP522 and SP524 is a highly integrated

serial transceiver that offers programmability

between interface modes through software con-

trol. The SP522 and SP524 offers the hardware

interface modes for RS-232 (V.28), RS-422A

(V.11), RS-423 (V.10), and RS-485. The inter-

face mode selection is done via two control

pins. The SP522 contains two (2) independent

drivers and two (2) independent receivers. The

SP524 is basically two SP522 functions on one

silicon, thus having four (4) drivers and four (4)

receivers.

The SP522/SP524 is ideally suited for low-cost

wide area network connectivity and other multi-

protocol applications. Based on our previous

multi-mode SP500 family, Sipex has allocated

specific transceiver cells or "building blocks"

from the SP503 and created the SP522. The

"building block" concept is that these small

transceiver cells can be packaged to offer a

simple low-cost solution to networking appli-

cations that need only two to four interface

modes. The SP522 can be connected in series

to build multiple channels needed for the spe-

cific application. Sipex has conveniently

doubled the SP522 transceiver cell into the

SP524 on a single silicon. For example in a 8-

channel application requiring eight transceiv-

ers, the design can be implemented using two

SP524 devices. The SP522 and SP524 can also

be implemented in series with our SP500 fam-

ily. An application needing 9-channels can use

the SP504 containing seven (7) transceivers

with the SP522.

THEORY OF OPERATION

The SP522 and SP524 are simply made up of

the drivers, receivers, and decoder. The devices

operate on three (3) power supplies; V

CC at

+5V, V

DD at +10V , and VSS at –10V. Each of

these circuit blocks are described in more detail

below.

Drivers

The SP522 has two (2) enhanced independent

drivers. Control for the mode selection is done

via a two–bit control word into DP0 and DP1.

The drivers are pre-arranged 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

required signal levels. The mode of each driver

in the different interface modes that can be

selected is shown in Figures 10 to 13.

There are three basic types of driver circuits —

RS-232, RS-423, and RS-485.

The RS-232 drivers output single–ended signals

with a minimum of +5V (with 3K

Ω and 2500pF

loading), and can operate up to 120Kbps. The

RS-232 drivers are used in RS-232 mode for all

signals, and also in V.35 mode where they are

used as the control line signals such as DTR and

RTS.

The RS-423 drivers are also single–ended

signals with a minimum voltage output

+3.6V (with 450

Ω loading) and can operate up

to 120Kbps. Open circuit V

OL and VOH

measurements are +4.0V to +6.0V when

supplying +5V to V

DD and VSS.

The RS-423

drivers can be used in RS-449, EIA-530, EIA-

530A and V.36 applications as Category II

signals from each of their corresponding

specifications.

The third type of driver produces a differential

signal that can maintain RS-485, +1.5V differ-

ential output levels with a worst case load of

Ω. The signal levels and drive capability of

the RS-485 drivers allow the drivers to also

support RS-422 (V.11) requirements of +2V

differential output levels with 100

Ω loads. The

RS-422 drivers can be used in RS-449,

EIA-530, EIA-530A and V.36 applications as

Category I signals which are used for clock and

data.

The drivers also have separate enable pins which

makes the SP522/SP524 helpful for half-duplex

applications. The enable pins will tri-state the

drivers when the ENT1 and ENT2 pins are at a

logic low ("0"). For the SP524, ENT3 and ENT4

are used for the two additional drivers. During

tri-stated conditions, the driver outputs will be

at a high impedance state.

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