KS8721B/BT
Micrel
Pin Number
Pin Name
Type(Note 1) Pin Function
25
INT#/
Ipu/O
Management Interface (MII) Interrupt Out: Latched as PHYAD[0] during power up
PHYAD0
/reset. See “Strapping Options” section for details.
22
CRS/
RMII_BTB
Ipd/O
MII Carrier Sense Output: The pull-up/pull-down value is latched as RMII BTB
during reset when RMII mode is selected. See “Strapping Options” section
for details.
23
26
GND
GND
Ground.
LED0/TEST
Ipu/O
Link/Activity LED Output:
Lnk/Act
No Link
Link
Pin State
LED Definition
“off”
H
L
“on”
Act
—
“Toggle”
The external pull-down enable test mode and only used for the factory test.
27
LED1/
SPD100/
noFEF
Ipu/O
Speed LED Output: Latched as SPEED (Register 0, bit 13) during power-up/reset.
See “Strapping Options” section for details.
Speed
10BT
Pin State
LED Definition
H
L
“off”
“on”
100BT
28
29
LED2/
DUPLEX
Ipu/O
Ipu/O
Full-duplex LED Output: Latched as DUPLEX (register 0h, bit 8) during power-up/
reset. See “Strapping Options” section for details.
Duplex
Half
Pin State
LED Definition
H
L
“off”
“on”
Full
LED3/
NWAYEN
Collision LED Output: Latched as ANEG_EN (register 0h, bit 12) during power-up/
reset. See “Strapping Options” section for details.
Collison
Pin State
LED Definition
No Collision
Collision
H
L
“off”
“on”
30
31
32
33
34
PD#
VDDRX
RX-
Ipu
Power Down. 1 = Normal operation, 0=Power down, Active low.
Analog 2.5V power supply.
Pwr
I
Receive Input: Differential receive input pins for FX, 100BaseTX or 10BaseT.
Receive Input: Differential receive input pin for FX, 100BaseTX or 10BaseT.
RX+
I
FXSD/FXEN
Ipd/O
Fiber Mode Enable / Signal Detect in Fiber Mode. If FXEN = 0, FX mode is
disable. The default is “0”. See “100BT FX Mode” section for more details.
35
36
GND
GND
GND
GND
Ground.
Ground.
Note 1. Pwr = power supply
GND = ground
I = input
O = output
I/O = bi-directional
Ipu = input w/ internal pull-up
Ipd = input w/ internal pull-down
Ipd/O = input w/ internal pull-down during reset, output pin otherwise
Ipu/O = input w/ internal pull-up during reset, output pin otherwise
PU = strap pin pull-up
PD = strap pin pull-down
NC = No connect
August 2003
7
KS8721B/BT
MICREL [ MICREL SEMICONDUCTOR ]
