Distinguishing Features ......................................................................................................................................... 1
Features ................................................................................................................................................................ 1
Other Features ...................................................................................................................................................... 1
Signal Information .................................................................................................................................................. 6
Application Information ........................................................................................................................................ 10
1394 Application Support Contact Information .................................................................................................... 12
Absolute Maximum Ratings ................................................................................................................................. 12
Ordering Information ............................................................................................................................................ 23
Table 1. Signal Descriptions................................................................................................................................... 7
Table 2. Absolute Maximum Ratings.................................................................................................................... 12
Table 3. Analog Characteristics............................................................................................................................ 13
Data Sheet, Rev. 3FW802A Low-Power PHY IEEE 1394A-2000
June 2001Two-Cable Transceiver/Arbiter Device
Description
The Agere Systems Inc. FW802A device provides the
analog physical layer functions needed to implement a
two-port node in a cable-based IEEE 1394-1995 and
IEEE 1394a-2000 network.
Each cable port incorporates two differential line transceivers. The transceivers include circuitry to monitor
the line conditions as needed for determining connection status, for initialization and arbitration, and for
packet reception and transmission. The PHY is
designed to interface with a link-layer controller (LLC).
The PHY requires either an external 24.576 MHz
crystal or crystal oscillator. The internal oscillator
drives an internal phase-locked loop (PLL), which
generates the required 400 MHz reference signal. The
400 MHz reference signal is internally divided to
provide the 49.152 MHz, 98.304 MHz, and
196.608 MHz clock signals that control transmission of
the outbound encoded strobe and data information.
The 49.152 MHz clock signal is also supplied to the
associated LLC for synchronization of the two chips
and is used for resynchronization of the received data.
The powerdown function, when enabled by the PD
signal high, stops operation of the PLL and disables all
circuitry except the cable-not-active signal circuitry.
The PHY supports an isolation barrier between itself
and its LLC. When /ISO is tied high, the link interface
outputs behave normally. When /ISO is tied low,
internal differentiating logic is enabled, and the outputs
become short pulses, which can be coupled through a
capacitor or transformer as described in the
IEEE 1394-1995 Annex J. To operate with bus-keeper
isolation, the /ISO pin of the FW802A must be tied
high.
Data bits to be transmitted through the cable ports are
received from the LLC on two, four, or eight data lines
(D[0:7]), and are latched internally in the PHY in
synchronization with the 49.152 MHz system clock.
These bits are combined serially, encoded, and
transmitted at 98.304 Mbits/s, 196.608 Mbits/s, or
393.216 Mbits/s as the outbound data-strobe
information stream. During transmission, the encoded
data information is transmitted differentially on the TPA
and TPB cable pair(s).
During packet reception, the TPA and TPB
transmitters of the receiving cable port are disabled,
and the receivers for that port are enabled. The
encoded data information is received on the TPA and
TPB cable pair. The received data-strobe information
is decoded to recover the receive clock signal and the
serial data bits. The serial data bits are split into two,
four, or eight parallel streams, resynchronized to the
local system clock, and sent to the associated LLC.
The received data is also transmitted (repeated) out of
the other active (connected) cable ports.
Both the TPA and TPB cable interfaces incorporate
differential comparators to monitor the line states
during initialization and arbitration. The outputs of
these comparators are used by the internal logic to
determine the arbitration status. The TPA channel
monitors the incoming cable common-mode voltage.
The value of this common-mode voltage is used during
arbitration to set the speed of the next packet
transmission. In addition, the TPB channel monitors
the incoming cable common-mode voltage for the
presence of the remotely supplied twisted-pair bias
voltage. This monitor is called bias-detect.
The TPBIAS circuit monitors the value of incoming
TPA pair common-mode voltage when local TPBIAS is
inactive. Because this circuit has an internal current
source and the connected node has a current sink, the
monitored value indicates the cable connection status.
This monitor is called connect-detect.
Both the TPB bias-detect monitor and TPBIAS
connect-detect monitor are used in suspend/resume
signaling and cable connection detection.
The PHY provides a 1.86 V nominal bias voltage for
driver load termination. This bias voltage, when seen
through a cable by a remote receiver, indicates the
presence of an active connection. The value of this
bias voltage has been chosen to allow interoperability
between transceiver chips operating from 5 V or 3 V
nominal supplies. This bias voltage source should be
stabilized by using an external filter capacitor of
approximately 0.33 µF.
The transmitter circuitry, the receiver circuitry, and the
twisted-pair bias voltage circuity are all disabled with a
powerdown condition. The powerdown condition
occurs when the PD input is high. The port transmitter
circuitry, the receiver circuitry, and the TPBIAS output
are also disabled when the port is disabled,
suspended, or disconnected.
The line drivers in the PHY operate in a highimpedance current mode and are designed to work
with external 112 Ω line-termination resistor networks.
One network is provided at each end of each twistedpair cable. Each network is composed of a pair of
series-connected 56 Ω resistors. The midpoint of the
pair of resistors that is directly connected to the
twisted-pair A (TPA) signals is connected to the PBIAS
voltage signal. The midpoint of the pair of
resistors that is directly connected to the twisted-pair B
(TPB) signals is coupled to ground through a parallel
RC network with recommended resistor and capacitor
values of 5 kΩ and 220 pF, respectively.
The value of the external resistors are specified to
meet the standard specifications when connected in
parallel with the internal receiver circuits.
The driver output current, along with other internal
operating currents, is set by an external resistor. This
resistor is connected between the R0 and R1 signals
and has a value of 2.49 kΩ ± 1%.
The FW802A supports suspend/resume as defined in
the IEEE 1394a-2000 specification. The suspend
mechanism allows an FW802A port to be put into a
suspended state. In this state, a port is unable to
transmit or receive data packets, however, it remains
capable of detecting connection status changes and
detecting incoming TPBias. When all ports of the
FW802A are suspended, all circuits except the bias
voltage reference generator, and bias detection
circuits are powered down, resulting in significant
power savings. The use of suspend/resume is
recommended.
Four signals are used as inputs to set four
configuration status bits in the self-identification (selfID) packet. These signals are hardwired high or low as
a function of the equipment design. PC[0:2] are the
three signals that indicate either the need for power
from the cable or the ability to supply power to the
cable. The fourth signal, C/LKON, as an input,
indicates whether a node is a contender for bus
manager. When the C/LKON signal is asserted, it
means the node is a contender for bus manager.
When the signal is not asserted, it means that the
node is not a contender. The C bit corresponds to bit
20 in the self-ID packet, PC0 corresponds to bit 21,
PC1 corresponds to bit 22, and PC2 corresponds to bit
23 (see Table 4-29 of the IEEE 1394-1995 standard
for additional details).
A powerdown signal (PD) is provided to allow a
powerdown mode where most of the PHY circuits are
powered down to conserve energy in battery-powered
applications. The internal logic in FW802A is reset as
long as the powerdown signal is asserted. A cable
status signal, CNA, provides a high output when none
of the twisted-pair cable ports are receiving incoming
bias voltage. This output is not debounced. The CNA
output can be used to determine when to power the
PHY down or up. In the powerdown mode, all circuitry
is disabled except the CNA circuitry. It should be noted
(continued)
that when the device is powered down, it does not act
in a repeater mode.
When the power supply of the PHY is removed while
the twisted-pair cables are connected, the PHY
transmitter and receiver circuitry has been designed to
present a high impedance to the cable in order to not
load the TPBIAS signal voltage on the other end of the
cable.
For reliable operation, the TPBn signals must be
terminated using the normal termination network
regardless of whether a cable is connected to a port or
not connected to a port. For those applications, when
FW802A is used with one of the ports not brought out
to a connector, those unused ports may be left
unconnected without normal termination. When a port
does not have a cable connected, internal connectdetect circuitry will keep the port in a disconnected
state.
Note: All gap counts on all nodes of a 1394 bus must
be identical. This may be accomplished by using
PHY configuration packets (see Section 4.3.4.3
of IEEE 1394-1995 standard) or by using two
bus resets, which resets the gap counts to the
maximum level (3Fh).
The link power status (LPS) signal works with the
C/LKON signal to manage the LLC power usage of the
node. The LPS signal indicates that the LLC of the
node is powered up or powered down. If LPS is inactive for more than 1.2 µs and less than 25 µs, PHY/link
interface is reset. If LPS is inactive for greater than
25 µs, the PHY will disable the PHY/link interface to
save power. FW802A continues its repeater function. If
the PHY then receives a link-on packet, the C/LKON
signal is activated to output a 6.114 MHz signal, which
can be used by the LLC to power itself up. Once the
LLC is powered up, the LPS signal communicates this
to the PHY and the PHY/link interface is enabled.
C/LKON signal is turned off when LPS is active or
when a bus reset occurs, provided the interrupt that
caused C/LKON is not present.
When the PHY/link interface is in the disabled state,
the FW802A will automatically enter a low-power
mode, if all ports are inactive (disconnected, disabled,
or suspended). In this low-power mode, the FW802A
disables its PLL and also disables parts of reference
circuitry depending on the state of the ports (some reference circuitry must remain active in order to detect
incoming TP bias). The lowest power consumption (the
microlow-power sleep mode) is attained when all ports
are either disconnected or disabled with the ports interrupt enable bit cleared. The FW802A will exit the lowpower mode when the LPS input is asserted high or
when a port event occurs that requires the FW802A
4Agere Systems Inc.
Data Sheet, Rev. 3FW802A Low-Power PHY IEEE 1394A-2000
June 2001Two-Cable Transceiver/Arbiter Device
Description
(continued)
to become active in order to respond to the event or to
notify the LLC of the event (e.g., incoming bias or disconnection is detected on a suspended port, a new
connection is detected on a nondisabled port, etc.).
The SYSCLK output will become active (and the PHY/
link interface will be initialized and become operative)
within 3 ms after LPS is asserted high, when the
FW802A is in the low-power mode.
CPS
LPS
/ISO
CNA
SYSCLK
LREQ
CTL0
CTL1
D0
D1
D2
D3
D4
D5
D6
D7
PC0
PC1
PC2
C/LKON
SE
SM
LINK
INTERFACE
I/O
RECEIVED
DATA
DECODER/
RETIMER
ARBITRATION
CONTROL
STATE
MACHINE
LOGIC
Two of the signals are used to set up various test
conditions used in manufacturing. These signals (SE
and SM) should be connected to V
Note: Active-low signals are indicated by “/” at the beginning of signal names, within this document.
Figure 2. Pin Assignments
SSA
V
5-6236.b (F)
66Agere Systems Inc.
Data Sheet, Rev. 3
June 2001
FW802A Low-Power PHY IEEE
Two-Cable Transceiver/Arbiter Device
Signal Information
Table 1. Signal Descriptions
PinSignal*TypeName/Description
18C/LKONI/OBus Manager Capable Input and Link-On Output. On hardware reset,
15CNAOCable-Not-Active Output. CNA is asserted high when none of the PHY
24CPSICable Power Status. CPS is normally connected to the cable power
3CTL0I/OControl I/O. The CTLn signals are bidirectional communications control
4CTL1
5, 6, 8,
9, 10, 11,
12, 13
23/ISOILink Interface Isolation Disable Input (Active-Low). /ISO controls the
* Active-low signals are indicated by “/ ” at the beginning of signal names, within this document.
D[0:7]I/OData I/O. The Dn signals are bidirectional and pass data between the
(continued)
this pin is used to set the default value of the contender status indicated
during self-ID. The bit value programming is done by tying the signal
through a 10 kΩ resistor to V
(low, not bus manager capable). Using either the pull-up or pull-down
resistor allows the link-on output to override the input value when necessary.
After hardware reset, this pin is set as an output. If the LPS is inactive,
C/LKON indicates one of the following events by asserting a 6.114 MHz
signal.
1. FW802A receives a link-on packet addressed to this node.
2. Port_event register bit is 1.
3. Any of the Timeout, Pwr_Fail, or Loop register bits are 1 and the
Resume_int register bit is also 1. Once activated, the C/LKON output
will continue active until the LPS becomes active. The PHY also deasserts the C/LKON output when a bus reset occurs, if the C/LKON is
active due solely to the reception of a link-on packet.
Note: If an interrupt condition exists which would otherwise cause the
C/LKON output to be activated if the LPS were inactive, the
C/LKON output will be activated when the LPS subsequently
becomes inactive.
ports are receiving an incoming bias voltage. This circuit remains active
during the powerdown mode.
through a 400 kΩ resistor. This circuit drives an internal comparator that
detects the presence of cable power. This information is maintained in
one internal register and is available to the LLC by way of a register read
(see Table 8, Register 0).
signals between the PHY and the LLC. These signals control the passage
of information between the two devices. Bus-keeper circuitry is built into
these terminals.
PHY and the LLC. Bus-keeper circuitry is built into these terminals.
operation of an internal pulse differentiating function used on the
PHY-LLC interface signals, CTLn and Dn, when they operate as outputs.
When /ISO is asserted low, the isolation barrier is implemented between
PHY and its LLC (as described in Annex J of IEEE 1394-1995).
/ISO is normally tied high to disable isolation differentiation. Bus-keepers
are enabled when /ISO is high (inactive) on CTL, D, and LREQ. When
/ISO is low (active), the bus-keepers are disabled. Please refer to Agere’s
application note AP98-074CMPR for more information on isolation.
16LPSILink Power Status. LPS is connected to either the V
DD
LLC or to a pulsed output that is active when the LLC is powered for the
purpose of monitoring the LLC power status. If LPS is inactive for more
than 1.2 µs and less than 25 µs, interface is reset. If LPS is inactive for
greater than 25 µs, the PHY will disable the PHY/Link interface to save
power. FW802A continues its repeater function.
1LREQ ILink Request. LREQ is an output from the LLC that requests the PHY to
perform some service. Bus-keeper circuitry is built into this terminal.
44, 45, 46,
NC—No Connect.
47, 48
20PC0IPower-Class Indicators. On hardware reset, these inputs set the default
21PC1
22PC2
value of the power class indicated during self-ID. These bits can be
programmed by tying the signals to V
(high) or to ground (low).
DD
19PDIPowerdown. When asserted high, PD turns off all internal circuitry except
the bias-detect circuits that drive the CNA signal. Internal FW802A logic is
kept in the reset state as long as PD is asserted. PD terminal is provided
for backward compatibility. It is recommended that the FW802A be
allowed to manage its own power consumption using suspend/resume in
conjunction with LPS. C/LKON features are defined in 1394a-2000.
57PLLV
DD
—Power for PLL Circuit. PLLV
supplies power to the PLL circuitry
DD
portion of the device.
58PLLV
SS
—Ground for PLL Circuit. PLLVSS is tied to a low-impedance ground
plane.
54R0ICurrent Setting Resistor. An internal reference voltage is applied to a
resistor connected between R0 and R1 to set the operating current and
the cable driver output current. A low temperature-coefficient resistor
55R1
(TCR) with a value of 2.49 kΩ ± 1% should be used to meet the
IEEE 1394-1995 standard requirements for output voltage limits.
61/RESETIReset (Active-Low). When /RESET is asserted low (active), the FW802A
is reset. An internal pull-up resistor, which is connected to V
DD
, is
provided, so only an external delay capacitor is required. This input is a
standard logic buffer and can also be driven by an open-drain logic output
buffer.
28SEITest Mode Control. SE is used during the manufacturing test and should
be tied to V
SS
.
29SMITest Mode Control. SM is used during the manufacturing test and should
be tied to V
SS
.
63SYSCLKOSystem Clock. SYSCLK provides a 49.152 MHz clock signal, which is
synchronized with the data transfers to the LLC.
36TPA0+Analog I/O Portn, Port Cable Pair A. TPAn is the port A connection to the twisted-
41TPA1+
pair cable. Board traces from each pair of positive and negative differential signal pins should be kept matched and as short as possible to the
external load resistors and to the cable connector.
* Active-low signals are indicated by “/ ” at the beginning of signal names, within this document.
88Agere Systems Inc.
Loading...
+ 16 hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.