DP83934AVQB National Semiconductor, DP83934AVQB Datasheet - Page 14

• Manufacturer Part Number: DP83934AVQB
• Description: IC CTRLR ORIENT NETWORK 160PLCC
• Manufacturer: National Semiconductor

Specifications of DP83934AVQB

• Controller Type: Network Interface Controller (NIC)
• Interface: Twisted Pair
• Voltage - Supply: 4.75 V ~ 5.25 V
• Current - Supply: 140mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 160-MQFP, 160-PQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *DP83934AVQB

3 0 Functional Description
3 2 IEEE 802 3 ENCODER DECODER (ENDEC) UNIT
The Encoder Decoder (ENDEC) unit is the interface be-
tween either the Twisted Pair Interface Module or the Ether-
net transceiver and the Media Access Control (MAC) unit
Providing the Manchester data encoding and decoding
functions for IEEE 802 3 Ethernet Thin-Ethernet or Twisted
Pair types of local area networks the ENDEC operations of
SONIC-T are identical to those of the DP83910A CMOS
Serial Network Interface device During transmission the
ENDEC unit combines non-return-zero (NRZ) data from the
MAC section and clock pulses to produce Manchester data
and sends the converted data differentially to the transceiv-
er Conversely during reception an analog Phase Lock
Loop (PLL) decodes the Manchester data into both NRZ
formatted data and a receive clock The SONIC-T ENDEC
unit is a functionally complete Manchester encoder decod-
er incorporating a balanced driver and receiver an on-board
crystal oscillator a collision signal translator and a diagnos-
tic loopback The features include
3 2 1 ENDEC Operation
The primary function of the ENDEC unit (Figure 3-5) is to
perform the encoding and decoding necessary for compati-
bility between the differential pair Manchester encoded data
of the transceiver and the Non-Return-to-Zero (NRZ) serial
data of the MAC unit data line In addition to encoding and
decoding the data stream the ENDEC also supplies all of
the special signals (e g collision detect carrier sense and
clocks) necessary to the MAC unit The signals provided to
the MAC unit from the on-chip ENDEC are also provided as
outputs to the user
Compatibility with Ethernet I and II
10BASE5 10BASE2 and 10BASE-T
10Mb s Manchester encoding decoding with receive
clock recovery
No precision components requirement
Loopback capability for diagnostics
Squelch circuitry at the receive and collision inputs reject
noise
Connection to the transceiver (Attachment Unit Inter-
face) cable via external pulse transformer
(Continued)
IEEE 802 3
14
Manchester Encoder and Differential Output Driver
During transmission to the network the ENDEC unit trans-
lates the NRZ serial data from the MAC unit into differential
pair Manchester encoded data To perform this operation
the NRZ bit stream from the MAC unit is passed through the
Manchester encoder block of the ENDEC unit Once the bit
stream is encoded it is transmitted out differentially to the
transmit differential pair through the transmit driver
The SONIC-T Controller is compatible with the IEEE 802 3
‘‘full-step’’ standard That is the Transmit
differential outputs are at equal voltages while they are idle
at the primary of the isolation transformer at the network
interface This voltage relationship provides a zero differen-
tial voltage for operation with transformer coupled loads
(See Section 8 1 for network interfacing considerations )
Manchester Decoder During reception from the network
the differential receive data from the transceiver is convert-
ed from Manchester encoded data into NRZ serial data and
a receive clock which are sent to the receive data and
clock inputs of the MAC unit To perform this operation the
signal is passed to the PLL decoder block once it is re-
ceived from the differential receiver The PLL decodes the
data and generates a data receive clock and a NRZ serial
data stream to the MAC unit
Data typically becomes valid from the decoder within 6 bit
times and the decoder detects the end of a frame when no
more mid-bit transitions are detected (See Section 8 1 for
network interfacing considerations )
Special Signals In addition to performing the Manchester
encoding and decoding function the ENDEC unit provides
control and clocking signals to the MAC unit The ENDEC
sends a carrier sense (CRS) signal that indicates to the
MAC unit that data is present from the network on the
ENDEC’s receive differential pair When the ENDEC’s colli-
sion receiver detects a 10 MHz signal on the differential
collision input pair the ENDEC unit provides the MAC unit
with a collision detection signal (COL) COL indicates that a
collision is taking place somewhere on the network
a
and Transmit
b