THEORY OF OPERATION
The SP526 device is made up of 1) the drivers,
2) the receivers, and 3) a charge pump.
Drivers
The SP526 has four enhanced independent
drivers. Control for the mode selection is done
via a two–bit control word into DP0 and DP1.
The drivers are prearranged such that for each
mode of operation, the relative position and
functionality of the drivers are set up to
accommodate 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 Table 1.
There are four basic types of driver circuits —
RS-232 (V.28), RS-423 (V.10), RS-422 (V.11),
and RS-485.
The RS-232 (V.28) drivers output single–ended
signals with a minimum of
5V (with 3K &
2500pF loading), and can operate to at least
120Kbps. Since the SP526 uses a charge pump
to generate the RS-232 output rails, the driver
outputs will never exceed 10V.
The RS-423 (V.10) drivers are also single–
ended signals which produce open circuit V
OL
and V
OH
measurements of 4.0V to 6.0V.
When terminated with a 450 load to ground,
the driver output will not deviate more than 10%
of the open circuit value. This is in compliance
FEATURES
The SP526 contains highly integrated serial
transceivers that offer programmability between
interface modes through software control. The
SP526 offers the hardware interface modes for
RS-232 (V.28), RS-423 (V.10), RS-422 (V.11),
and RS-485. The interface mode selection is
done via two control pins.
The SP526 has four drivers, four receivers, and
an on-board charge pump that is ideally suited
for low-cost wide area network connectivity
and other multi-protocol applications. Based on
our multi-mode SP500 family, Sipex has
allocated specific transceiver cells, or "building
blocks," from this product series and created the
SP526
. Sipex's "building blocks" concept
allows these small transceiver cells to be
packaged to offer a simple low-cost solution to
networking applications that need only 4
interface modes. For example, an 8-channel
applications requiring eight serial transceivers
can be achieved implementing two SP526
devices. The SP526 can be implemented in
series with other devices in our SP500 family.
A 9-channel network application can be achieved
implementing the SP505 which contains seven
transceivers in conjunction with the SP526
.
1D 0D
SREVIRD SREVIECER
1T 2T 3T 4T 1R 2R 3R 4R
0 0 e
doMetatS-irTnistuptuOxRdnaxT-NWODTUHS
0 1 1
1.V 11.V 11.V 01.V 11.V 11.V 11.V 11.V
1 0 1
1.V 11.V 01.V 01.V 11.V 11.V 11.V 11.V
1 1 8
2.V 82.V 82.V 82.V 82.V 82.V 82.V 82.V
Table 1. SP526 Driver and Receiver Mode Selection with the Control Lines D1 and D0
