SP505ACF datasheet(22/36 Pages) SIPEX

22 / 36 page

Rev. 7/9/03

SP505 Multi–Mode Serial Transceiver

All receivers include a fail-safe feature that

outputs a logic "1" when the receiver inputs are

open. The differential receivers allocated for

data and clock signals (RxD, RxC, and SCT)

have advanced fail-safe that outputs a logic "1"

when the inputs are either open, shorted, or

terminated. Other discrete or integrated imple-

mentations require external pull-up and pull-

down resistors to define the receiver output

state. For single-ended V.28 receivers, there are

internal 5k

Ω pull-down resistors on the inputs

which produces a logic high ("1") at the receiver

outputs. The single-ended V.10 receivers pro-

duce a logic LOW ("0") on the output when the

inputs are open. This is due to an internal pull-

up device connected to the input. The differen-

tial receivers have the same internal pull-up

device on the non-inverting input which pro-

duces a logic HIGH ("1") at the receiver output,

representing an "OFF" state to the HDLC con-

troller. The three differential receivers when

configured in V.35 mode (RxD, RxC & SCT)

will also include fail-safe even when the internal

termination resistor network is connected and

the inputs are either shorted or floating.

Decoder

The SP505 has the ability to change the inter-

face mode of the drivers or receivers via a 4–bit

switch. The decoder for the drivers and receiv-

ers can be latched through a control pin.

The control word can be latched either high or

low to write the appropriate code into the SP505.

The codes shown in Tables 1 and 2 are the only

specified, valid modes for the SP505. Unde-

fined codes may represent other interface modes

not specified (consult the factory for more infor-

mation). The drivers and receivers are con-

trolled with the data bits labeled DEC

3–DEC0.

All of the drivers outputs and receiver outputs

can be put into tri-state mode by writing 0000 to

the driver decode switch. All internal termina-

tion networks are switched off during this mode.

Individual tri-state capability is possible for all

drivers through each driver's own enable control

input. The SCT receiver also contains an indi-

vidual enable input. When this control pin is

disabled (logic "0"), the V.11 and V.35 input

termination is deactivated. The 0000 decoder

word will override the enable control line for the

one receiver (SCT).

The SP505 contains internal loopback capabili-

ties for self-diagnostic tests. Loopback is en-

abled through the decoder. To initiate single-

ended mode loopback, the decoder word is 1010.

To initiate differential mode loopback, the de-

coder word is 1011. The minimum transmission

rates into the SP505 under loopback conditions

are 120kbps for single-ended mode and 5Mbps

for differential mode. The driver outputs are tri-

stated and the receiver inputs are disabled dur-

ing loopback. The receiver input impedance

during loopback is approximately 10k

Ω.

The SP505 is equipped with a latch control for

the four (4) decoder bits. The latch control pin

is pin 8 of the SP505. The latch control is active

low, a logic low on pin 8 will latch the decoder

signals. A logic "1" on pin 8 will force the latch

to be transparent to the user. A pulse width of at

least 30ns is required to latch the decoder for the

next mode. The resultant output is typically

600ns after the latch control pin is toggled

assuming that the decoder word is set.

NET1/2 & TBR2 European Compliancy

As with all of Sipex's previous multi-protocol

serial transceiver ICs, the drivers and receivers

have been designed to meet all the requirements

to NET1/2. The SP505 is internally tested to all

the NET1/2 physical layer testing parameters

and the ITU Series V specifications.

With the emergence of ETSI TBR2 (Technical

Basis for Regulation) document now in place as

an alternative for European compliancy, Sipex

has tested the SP505 to TBR2 specifications to

ensure "CE" approval for either testing method.

The SP505 was externally tested by TUV

Telecom Services, Division of TUV Rheinland,

and passed both NET1/2 and TBR2 require-

ments. Test reports (NET2/052101/98 for NET1/2 and CTR2/

05101/98 for TBR2)

can be furnished upon request.

Please note that although the SP505 adheres to

NET1/2 testing; any complex or unusual con-

figuration should be double-checked to ensure

NET compliance. Consult factory for details.

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