SP505AN Datasheet, PDF (22/30 Pages) Sipex Corporation – Multi-Protocol Serial Transceivers

has a logic LOW enable. The receivers use a logic
LOW enable for its receiver enable lines except for
the TM receiver, which has a logic HIGH enable.
The DIP switches for the SP507EB evaluation board
is such that the "down" position of the switch will
be considered "ON" and the "up" position will be
considered "OFF", regardless up enable polarity.
Note that the SP507EB Rev. A boards will have the
label on the switches reversed. But the true state is all
transceivers enabled when rocker switches are
positioned down.
On the right side of the board with the driver inputs,
there is a common bus named INPUT, which has
access points next to each driver input. This bus is
added on the board for convenience so that the driver
inputs can all be connected together via jumper wires
to this bus. The INPUT trace can be followed on the
top layer of the board.
The other DIP switch will configure the physical
layer protocol desired on the transceiver IC.
The SP507 uses three bits M0, M1, and M2.
The decoder bits will be logic HIGH when the
toggle position is "down" The /TERM_OFF will be
logic LOW when in the rocker "down" position.
The /LATCH pin will be logic HIGH in the rocker
"down" position.
The "FUSE" connection on the board is included to
connect the shield ground to the signal ground.
A 1-Ω to 100Ω resistor can be placed into the FUSE
position. EIA-530, EIA-530A, and RS-449 stan-
dards state that a 100Ω, 1/4W resistor should isolate
the shield or earth ground from the signal ground on
the DTE side.
Loopbacks and other testing can be easily performed
by the use of jumper wires or cables. All necessary
points on the boards are labelled. The SP507
Evaluation Board (Rev. A) schematic is shown on
Figure 36. The SP507EB (Rev A.) layout plot is
shown on Figure 38.
SP505, 506 and SP507 Retrofits
Along with our SP506 Evaluation (SP506EB) and
SP507 Evaluation Boards (SP507EB), Sipex also
offers SP506 or SP507 Retrofit Boards (SP506RB
and SP507RB). Shown in Figure 37, these retrofit
boards are design to map onto existing motherboards
and replace an existing serial port platform. These
boards are approximately 1.375" x 1.375" and
contain the four charge pump capacitors and one
Schottky diode needed for compliant operation.
The boards also have the connections for driver
inputs and outputs and receiver inputs and outputs.
Using a ribbon type cable or "flex-board", the analog
I/Os can be mapped to the appropriate pin assignment
on the serial port connector and the TLL/CMOS
I/Os to the HDLC serial controller IC. The equipment's
existing serial transceiver ICs can be depopulated
and replaced by the retrofit board.
Sipex usually prefers to perform the retrofitting
in-house. But the experienced designer can also retrofit
the serial port as well. Once connected properly, the
functionality and electrical performance will be
transparent to the user. Sipex will perform the
necessary testing to ensure the retrofit is electrically
transparent and complaint to the physical layer
specifications. Sipex has already passed homologation
testing per NET1/2 and TBR2 with this board
retrofitted onto a router.
SP505/6/7APN/03
Figure 37. SP507 Retrofit Board
SP505, SP506, SP507 Application Note
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