7
NWK914D
Fig.6 Simplified 100BASE-TX system block diagram showing NWK914D external components
EXTERNAL REQUIREMENTS
The NWK914D requires a number of external components
for the device to function correctly and these are shown in
the simplified 100BASE-TX application circuit in Fig.6 and
the component value information given in Table 2.
Note that the values of R2, R5 and R6 vary depending
upon application. When using 1:1 magnetics, use the values
shown in the middle of Table 2 with note "1:1 magnetics".
When using 2:1 magnetics use the values shown in the last
two lines of Table 2. Please refer to the Transmit Line Driver
section on pages 3-4 for more information on these values.
For more detailed Application information please contact
your local Sales Office.
GLOSSARY OF TERMS AND ABREVIATIONS
MAC
Media Access Control
MLT-3
Multi Level Transmit -3 levels
NRZ
Non Return To Zero
NRZI
Non Return to Zero Inverse
PCS
Physical Coding Sublayer
PHY
PHYsical Layer
PLL
Phase Locked Loop
PMD
Physical Media Dependent
UTP
Unshielded Twisted Pair
RX
Receive
STP
Shielded Twisted Pair
TX
Transmit
UTP
Unshielded Twisted Pair
VCO
Voltage Controlled Oscillator
1K
100pF
TxV
cc
6.2K
.01
μ
F
R6
R5
15
15
68
0.1
μ
F
Xtal Osc.
LFTA
REFCLK
LFTB TXREF
TXGND
TXOP
TXON
RXIP
RXIN
LFRB
LFRA
TDAT0-4
TXC
RXC
RDAT0-4
.033
μ
F
C2
RJ45
5
5
PCS
or
MAC
(with
embedded
PCS)
1:1
M
A
G
N
E
T
I
C
S
NWK914D
R1
C1
R2
See Table 2 for
these resistor values
CT
C4
R7
R9
R8
R3
C3
REF.
VALUE
TOL.
FUNC.
NOTES
C1
C2
C3
100pF
0.033
μ
F
.01
μ
F
20%
20%
20%
loop fltr
loop fltr
loop fltr
R1
R2
R3
R5,R6
R7,R8
R9
1K
1300
6.2K
50
15
68
1%
1%
1%
1%
1%
1%
loop fltr
tx ref
loop fltr
xmit
rcv pad
rcv pad
1:1 magnetics
1:1 magnetics
R2
R5,R6
2.6K
200
1%
1%
tx ref
xmit
2:1 magnetics
2:1 magnetics
CT on transformer connects directly to
TX V
CC
with C4 omitted
2:1 magnetics
Table 2: External components
NWK914B
NWK914S
NWK914D
Base Line Wander Correction
TXREF resistor with 1:1 magnetics
-
improved to 100m
680
improved to 100m
620
1300
Table 3: Differences between NWK914B, NWK914S and NWK914D