Data Sheet
July 2000
LU6612
FASTCAT Single-FET for 10Base-T/100Base-TX
MODE Selection
LU6612 can be forced to operate in specific operating modes. This is achieved by configuring the MODE pins to
the appropriate values at powerup/reset. The strapping options of the MODE pins are latched on reset to set the
default values of various registers. The values can be modified by writing into the registers. The MODE[2:0] pins
have 100 kΩ internal pull-ups. If MODE[2:0] are left floating, LU6612 will default to all capable, autonegotiation
enabled mode.
The different modes of operation of LU6612 and the register bits affected are presented in the following table.
Table 20. Operation Modes of LU6612
Register.Bit
MODE
[2:0]
Definition
0.8 0.10 0.12 0.13 4.5 4.6 4.8
000 10Base-T, half-duplex with autonegotiation disabled
001 10Base-T, full-duplex with autonegotiation disabled
010 100Base-TX, half-duplex with autonegotiation disabled
011 100Base-TX, full-duplex with autonegotiation disabled
100 Advertise 100Base-TX, half-duplex autonegotiation enabled
101 Reserved
0
1
0
0
0
0
0
0
1
1
0
1
1
1
0
0
0
1
0
0
1
1
0
0
1
0
0
1
0
0
1
1
0
0
0
—
0
—
1
—
0
—
1
—
1
—
1
—
0
110 Isolate MII
111 All capable, autonegotiation enabled
0
0
1
1
1
1
1
Table 21. LU6612 Crystal Specifications
Parameter
Requirement
Type
Quartz Fundamental Mode
Frequency
25 MHz
Stability
±25 ppm, 0—70 °C
7 pF
Shunt Capacitor
Load Capacitor
Series Resistance
20 pF
<30 Ω
Lucent Technologies Inc.
23
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