SP503 datasheet(20/29 Pages) SIPEX

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Date: 7/29/04

SP503 Multiprotocol 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 con-

trol 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 a ribbon cable. There are

also open areas on the PC board to add addi-

tional circuitry to support application-specific

requirements.

Manual Control

The SP502/SP503EB will support both the

SP502 or SP503 multi-mode serial transceiv-

ers. 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 receiver and the TT driver. Due to this

internal connection, the RxT receiver inputs can

be accessed 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

and 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 corresponding 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 a 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 20k

Ω pulldown 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 22

µF (16V) and be placed as close to the

unit as possible; tantalum capacitors are sug-

gested. The decoupling capacitor must be a

minimum of 1

µF; depending upon the operating

environment, 10

µF 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 54

Ω loads. The power and

ground inputs can be supplied through either the

banana jacks on the evaluation board (Red = V

= +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.

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