DP83955AV National Semiconductor, DP83955AV Datasheet - Page 31

• 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

Pin Name
5 0 Functional Description
5 6 PROCESSOR AND DISPLAY INTERFACE
HARDWARE CONNECTION
Display Update Cycles
The LERIC possesses control logic and interface pins which
may be used to provide status information concerning activi-
ty on the attached network segments and the current status
of repeater functions These status cycles are completely
autonomous and require only simple support circuitry to pro-
duce the data in a form suitable for a light emitting diode
‘‘LED’’ display The display may be used in one of two
modes
1 Minimum Mode General Repeater Status LEDs
2 Maximum Mode Individual Port Status LEDs
Minimum mode intended for simple LED displays makes
available four status indicators The first LED denotes
whether the LERIC has been forced to activate its jabber
protect functions The remaining 3 LEDs indicate if any of
the LERIC’s network segments are (1) experiencing a colli-
sion (2) receiving data (3) currently partitioned When mini-
mum display mode is selected the only external compo-
nents required are a 74LS374 type latch the LEDs and their
current limiting resistors
Maximum mode differs from minimum mode by providing
display information specific to individual network segments
This information denotes the collision activity packet recep-
tion and partition status of each segment In the case of
10BASE-T segments the link integrity status and polarity of
the received data are also made available The wide variety
of information available in maximum mode may be used in
its entirety or in part thus allowing the system designer to
choose the appropriate complexity of status display com-
mensurate with the specification of the end equipment
Note ACOL
Signal
D(7 4)
STR
D0
D1
D2
D3
AREC
APART
JAB
e
e
e
Mnemonic
e
Any Port Jabbering
Any Port Collision
Any Port Reception
APART
AREC
ACOL
Port Partitioned
JAB
Provides status information indicating if there is a collision occurring on one of the segments attached to
this LERIC
Provides status information indicating if one of this LERIC’s ports is receiving a data or collision packet
from a segment attached to this LERIC
Provides status information indicating that the LERIC has experienced a jabber protect condition
Provides status information indicating if one of the LERIC’s segments is partitioned
No operation
This signal is the latch enable for the 374 type latch
TABLE 5-3 Status Display Pin Functions in Minimum Mode
(Continued)
Function in MINIMUM MODE
31
The signals provided and their timing relationships have
been designed to interface directly with 74LS259 type ad-
dressable latches The number of latches used being de-
pendent upon the complexity of the display Since the latch-
es are octal a pair of latches is needed to display each type
of segment specific data (7 ports means 7 latch bits) The
accompanying Tables 5-3 and 5-4 show the function of the
interface pins in minimum and maximum modes Figure 5-10
shows the location of each port’s status information when
maximum mode is selected This may be compared with the
connection diagram (Figure 5-9)
Immediately following the MLOAD Operation (when the
MLOAD pin transitions to a high logic state) the display
logic performs an LED test operation This operation lasts
one second and while it is in effect all of the utilized LEDs
will blink on Thus an installation engineer is able to test the
operation of the display by forcing the LERIC into a reset
cycle (MLOAD forced low) The rising edge on the MLOAD
pin starts the LED test cycle During the LED test cycle
the LERIC does not perform packet repetition opera-
tions
The status display possesses a capability to lengthen the
time an LED is active At the end of the repetition of a pack-
et the display is frozen showing the current activity This
freezing lasts for 30 ms or until a subsequent packet is re-
peated Thus at low levels of packet activity the display
stretches activity information to make it discernable to the
human eye At high traffic rates the relative brightness of
the LEDs indicates those segments with high or low activity