SP522 Datasheet, PDF (9/23 Pages) Sipex Corporation – Low-Cost Programmable Multi-Protocol 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 V_SS 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 3KΩ 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 of
+3.6V (with 450Ω loading) and can operate up
to 120Kbps. Open circuit V_OL and V_OH
measurements are +4.0V to +6.0V when
supplying +5V to V_DD and V_SS. 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
54Ω. 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 100Ω 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.
Rev. 7/10/03
SP522 Multi–Mode Serial Transceivers
9
© Copyright 2003 Sipex Corporation