DP83905AVQB National Semiconductor, DP83905AVQB Datasheet - Page 19

• Manufacturer Part Number: DP83905AVQB
• Description: IC CONTROLR AT/LAN TP IN 160PQFP
• Manufacturer: National Semiconductor
• Series: AT/LANTIC™r

Specifications of DP83905AVQB

• Controller Type: AT, LAN Twisted-Pair Interface Controller
• Voltage - Supply: 4.75 V ~ 5.25 V
• Current - Supply: 100mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 160-BFQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -
• Other names: *DP83905AVQB

4 0 Functional Description
4 8 TWISTED PAIR INTERFACE MODULE
The TPI consists of five main logical functions
a) The Receiver Smart Squelch responsible for determin-
b) The Collision function checks for simultaneous transmis-
c) The Link Detector Generator checks the integrity of the
d) The Jabber disables the transmitter if it attempts to
e) The TX Driver and Pre-emphasis transmits Manchester
cable connecting the two twisted pair MAUs
ing when valid data is present on the differential receive
inputs (RXI
sion and reception of data on the TXO
transmit a longer than legal packet
encoded data to the twisted pair network via the sum-
ming resistors and transformer filter
g
) and receiving the data
FIGURE 13 Twisted Pair Interface Module Block Diagram
g
and RXI
(Continued)
g
pins
19
Figure 14 shows the operation of the smart squelch in
Receiver and Smart Squelch
The AT LANTIC Controller implements an intelligent re-
ceive squelch on the RXI
impulse noise on the receive inputs will not be mistaken for
a valid signal
The squelch circuitry employs a combination of amplitude
and timing measurements to determine the validity of data
on the twisted pair inputs There are two voltage level op-
tions for the smart squelch One mode 10BASE-T mode
uses levels that meet the 10BASE-T specification The sec-
ond mode reduced squelch mode uses a lower squelch
threshold level and can be used in longer cable applica-
tions where smaller signal levels may be applied The
squelch level mode can be selected in the AT LANTIC Con-
troller configuration registers
10BASE-T mode
g
differential inputs to ensure that
TL F 11498 – 10