dp83846a National Semiconductor Corporation, dp83846a Datasheet - Page 18

• Manufacturer Part Number: dp83846a
• Description: Dsphyter ? Single 10/100 Ethernet Transceiver
• Manufacturer: National Semiconductor Corporation

decrease radiated emissions at certain frequencies by as
much as 20 dB. The DP83846A uses the PHY_ID (pins
PHYAD [4:0]) to set a unique seed value.
3.2.3 NRZ to NRZI Encoder
After the transmit data stream has been serialized and
scrambled, the data must be NRZI encoded in order to
comply with the TP-PMD standard for 100BASE-TX trans-
mission over Category-5 Unsheilded twisted pair cable.
binary_in
D
Q
Q
Figure 6. Binary to MLT-3 conversion
differential MLT-3
binary_minus
binary_plus
binary_in
18
3.2.4 Binary to MLT-3 Convertor / Common Driver
The Binary to MLT-3 conversion is accomplished by con-
verting the serial binary data stream output from the NRZI
encoder into two binary data streams with alternately
phased logic one events. These two binary streams are
then fed to the twisted pair output driver which converts the
voltage to current and alternately drives either side of the
transmit transformer primary winding, resulting in a minimal
current (20 mA max) MLT-3 signal. Refer to Figure 6 .
binary_minus
binary_plus
COMMON
DRIVER
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MLT-3