DP83955AV National Semiconductor, DP83955AV Datasheet - Page 35

• Manufacturer Part Number: DP83955AV
• Description: IC CTRLR RIC REPEATER 100-PQFP
• Manufacturer: National Semiconductor
• Series: LERIC™r

Specifications of DP83955AV

• Controller Type: LitE Repeater Interface Controller
• Voltage - Supply: 5V
• Current - Supply: 250mA
• Mounting Type: Surface Mount
• Package / Case: 84-LCC (J-Lead)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Operating Temperature: -
• Interface: -
• Other names: *DP83955AV

5 0 Functional Description
6 0 Port Block Functions
The LERIC has 7 port logic blocks (one for each network
connection) In addition to the packet repetition operations
already described the port block performs two other func-
tions
1 The physical connection to the network segment (trans-
2 It provides a means to protect the network from malfunc-
Each port has its own status and configuration register This
register allows the user to determine the current status of
the port and configure a number of port specific functions
6 1 TRANSCEIVER FUNCTIONS
The LERIC may connect to network segments in three
ways
1 Over AUI cable to transceiver boxes (Port 1)
2 Directly to board mounted transceivers
3 To twisted pair cable via a simple interface
The first method is only supported by LERIC Port 1 (the AUI
port) Options (2) and (3) are available on Ports 2 to 7 The
selection of the desired option is made at device initializa-
tion during the MLOAD operation The Transceiver Bypass
XBYPAS configuration bits are used to determine whether
the ports will utilize the on-chip 10BASE-T transceivers or
bypass these in favor of external transceivers Four possible
combinations of port utilization are supported (refer to Table
5-2)
1 All ports (2 to 7) use the external Transceiver Interface
2 Ports 2 and 3 use the external interface 4 to 7 use the
3 Ports 2 to 5 use the external interface 6 and 7 use the
4 All ports (2 to 7) use the internal 10BASE-T transceivers
ceiver function)
tioning segments (segment partition)
internal 10BASE-T transceivers
internal 10BASE-T transceivers
FIGURE 5-12 Processor Connection Diagram
(Continued)
35
10BASE-T Transceiver Operation
The LERIC contains virtually all the digital and analog cir-
cuits required for connection to 10BASE-T network seg-
ments The only additional active component is an external
driver package The connection for a LERIC port to a
10BASE-T segment is shown in Figure 6-1 The diagram
shows the components required to connect one of the
LERIC’s ports to a 10BASE-T segment (and lists a few mod-
ule P Ns and vendors) The major components are the driv-
er package a member of the 74ACT family and an integrat-
ed filter-transformer-choke module (or discrete combination
of these functions)
The operation of the 10BASE-T transceiver’s logical func-
tions may be modified by software control The default
mode of operation is for the transceivers to transmit and
expect reception of link pulses This may be modified if a
logic one is written to the GDLNK bit of a port’s status regis-
ter The port’s transceiver will operate normally but will not
transmit link pulses nor monitor their reception Thus the
entry to a link fail state and the associated modification of
transceiver operation will not occur
The on-chip 10BASE-T transceivers automatically detect
and correct the polarity of the received data stream This
polarity detection scheme relies upon the polarity of the re-
ceived link pulses and the end of packet waveform Polarity
detection and correction may be disabled through the
MLOAD operation
External Transceiver Operation
LERIC ports 2 to 7 may be connected to media other than
twisted-pair by opting to bypass the on-chip transceivers
When using external transceivers the user must perform
collision detection and the other functions associated with
an IEEE 802 3 Media Access Unit Figure 6-2 shows the
connection between a repeater port and a coaxial transceiv-
er using the AUI type interface
TL F 11240– 16