SP502 Datasheet, PDF (23/32 Pages) Sipex Corporation – Multi-Mode Serial Transceiver

SP502/SP503 EVALUATION BOARD
The SP502/SP503 Evaluation Board (EB) Is
designed to offer as much flexibility to the user as
possible. Each board comes equipped with an
80-pin QFP Zero-Insertion Force socket to allow
for testing of multiple devices. The control lines
and inputs and outputs of the device can be
controlled either manually or via a data bus under
software control. There is a 50-pin connector to
allow for easy connection to an existing system
via ribbon cable. There are also open areas on the
PC board to add additional circuitry to support
application-specific requirements.
Manual Control
The SP502/SP503EB will support both the
SP502 or SP503 multi-mode serial transceivers.
When used for the SP502, disregard all notation
on the board that is in [brackets] . The SP502 has
a half-duplex connection between the RxT re-
ceiver and the TT driver. Due to this internal
connection, the RxT receiver inputs can be ac-
cessed via the TT(a) and TT(b) pins. If the user
needs separate receiver input test pins, jumpers
JP1 and JP2 can be inserted to allow for separate
receiver inputs located at SCT(a) and SCT(b).
The corresponding TTL output for this receiver
is labeled as SCT. This test point is tied to pin 79
of the SP502 or SP503. Pin 7 of the evaluation
board is connected to the DIP switch, and is
labeled as (SCTEN). When used with the SP502,
this pin should be switched to a low state. When
the evaluation board is used with the SP503, pin
7 is a tri-state control pin for the SCT receiver.
The transceiver I/O lines are brought out to test
pins arranged in the same configuration as shown
elsewhere in this data sheet. A top layer silk-screen
shows the drivers and receivers to allow direct
correlation to the data sheet. The transmitter and
receiver decode bits are tied together and are
brought out to a DIP switch for manual control of
both the driver and receiver interface modes.
Since the coding for the drivers and receivers is
identical, the bits have been tied together. The
DIP switch has 7 positions, four of which are
reserved for the TDEC/RDEC control. The other
three are used as tri-state control pins. The labels
that are in [brackets] apply only to the SP503.
If a logic one is asserted, the corresponding red
LED will be lit. If a zero is asserted, the corre-
sponding red LED will not be lit.
Software Control
A 50-pin connector brings all the analog and
digital I/O lines, V_CC, and GND to the edge of the
card. This can be wired to the user’s existing
design via ribbon cable. The pinout for the
connector is described in the following section.
When the evaluation board is operated under
software control, the DlP switch should be set
up so that all bits are LOW (all LEDs off). This
will tie pull-down resistors from the inputs to
ground and let the external system control the
state of the control inputs.
Power and Ground Requirements
The evaluation board layout has been optimized
for performance by using basic analog circuit
techniques, The four charge-pump capacitors
must be 22µF (16V) and be placed as close to the
unit as possible; tantalum capacitors are sug-
gested. The decoupling capacitor must be a
minimum of 1µF; depending upon the operating
environment, 10µF should be enough for worst
case situations. The ground plane for the part
must be solid, extending completely under the
package. The power supplies for the device
should be as accurate as possible; for rated
performance ±5% is necessary. The power sup-
ply current will vary depending upon the se-
lected mode, the amount of loading and the data
rate. As a maximum, the user should reserve
200mA for I_CC. The worst-case operating mode
is RS-485 under full load of six (6) drivers
supplying 1.6V to 54Ω loads. The power and
ground inputs can be supplied through either the
banana jacks on the evaluation board (Red = V_CC
= +5V±5%; Black = GND) or through the con-
nector.
For reference, the 80-pin QFP Socket is a
TESCO part number FPQ-80-65-09A. The
50-pin connector is an AMP part number
749075-5.
Rev. 7/21/03
SP502 Multi-Mode Serial Transceiver
23
© Copyright 2003 Sipex Corporation