AM79C874VC AMD (ADVANCED MICRO DEVICES), AM79C874VC Datasheet - Page 28

• Manufacturer Part Number: AM79C874VC
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of AM79C874VC

• Lead Free Status / RoHS Status: Not Compliant

Power Savings Mechanisms
The power consumption of the device is significantly
reduced by its built-in power down features. Separate
power supply lines are also used to power the
10BASE-T circuitry and the 100BASE-TX circuitry.
Therefore, the two modes of operation can be turned-
on and turned-off independently. Whenever the Net-
PHY-1LP device is set to operate in a 100BASE-TX
mode, the 10BASE-T circuitry is powered down, and
when in 10BASE-T mode, the 100BASE-TX circuitry is
powered down.
28
1. Assumes configuration as in Figure 6.
2. The LED will not blink for the duration of a packet if the transmit and receive activity are simultaneously active ( i.e.,
3. Refer to Table 7, Table 8 and Table 9 for Mode, Duplex and Activity functions.
1. Use for non 7-wire interface configurations.
2. Use for 7-wire interface configurations.
Notes:
10 Mbps Half Duplex
10 Mbps Half Duplex
100 Mbps Half Duplex
100 Mbps Half Duplex
Full Duplex
Any
Link (Note 1)
Link (Note 2)
in opposite phase).
Collision
Receive
Mode
LEDCOL
LEDLNK
LEDLNK
LEDRX
Table 9. Activity LED Configuration in Advanced LED Mode
5 K
Reg 21, bit 10
CONF_ALED
X
X
0
1
0
1
Figure 6. Advanced LED Configuration
LED
LED
LED
LED
Reg 21, bit 9
LED_SEL
0
0
0
0
0
1
330
330
330
330
D A T A
Am79C874
VCC
VCC
VCC
LEDBTA/LEDBTB or
The NetPHY-1LP device offers the following power
management: Selectable Transformer, Power Down,
Unplugged, and Idle.
Selectable Transformer
The TX outputs can drive either a 1:1 transformer or a
1.25:1 transformer. The latter can be used to reduce
transmit power further. The current at the TX± pins for
a 1:1 ratio transformer is 40 mA for MLT-3 and 100 mA
for 10BASE-T. Using the 1.25:1 ratio reduces the cur-
rent to 30 mA for MLT-3 and 67 mA for 10BASE-T.
The cost of using the 1.25:1 option is in impedance
coupling. The reflected capacitance is increased by the
LEDTXA/LEDTXB
LEDTXA/LEDTXB
LEDTXA/LEDTXB
LEDBTA/LEDBTB
LEDBTA/LEDBTB
LEDTX, LEDRX
S H E E T
LEDBTA
LEDBTB
Pin
LEDTXA
LEDTXB
100BASE-TX LED Indicator
10BASE-T LED Indicator
300
300
Blinks on Tx and Rx activity
Blinks on Rx activity only
Blinks on Tx and Rx activity
Blinks on Rx activity only
Blinks on Rx activity only
Blinks on respective pins
1
LED Status
Dual-Color
LED
Dual-Color
LED
2
22236G-8
22235K