Datasheet
Micrel, Inc. KS8721BL/SL
June 2009
8
M9999-062509-1.3
Pin Number Pin Name Type
(1)
Pin Function
24 VDDIO P Digital IO 2.5/3.3V tolerant power supply. 3.3V power input of voltage regulator.
See “Circuit Design Ref. for Power Supply” section for details.
25 INT#/
PHYAD0
Ipu/O Management Interface (MII) Interrupt Out. Interrupt level set by Register 1f, bit 9.
During reset, latched as PHYAD[0]. See “Strapping Options” section for details.
26 LED0/
TEST
Ipu/O Link/Activity LED Output. The external pull-down enable test mode and only used for
the factory test. Active low.
Link/Act Pin State LED Definition PHYAD0
No Link H “Off”
Link L “On”
Act – “Toggle”
27 LED1/
SPD100/
nFEF
Ipu/O Speed LED Output. Latched as SPEED (Register 0, bit 13) during power-up/ reset. See
“Strapping Options” section for details. Active low.
Speed Pin State LED Definition
10BT H “Off”
100BT L “On”
28 LED2 Ipu/O Full-duplex LED Output. Latched as DUPLEX (register 0h, bit 8) during power-up/ reset.
See “Strapping DUPLEX Options” section for details. Active low.
Duplex Pin State LED Definition
Half H “Off”
Full L “On”
29 LED3/
NWAYEN
Ipu/O Collision LED Output. Latched as ANEG_EN (register 0h, bit 12) during power-up/
reset. See “Strapping Options” section for details.
Collision Pin State LED Definition
No Collision H “Off”
Collision L “On”
30 PD# Ipu Power Down. 1 = Normal operation, 0 = Power-down. Active low.
31 VDDRX P Analog 2.5V power supply. See “Circuit Design Ref. for Power Supply” section for
details.
32 RX- I Receive Input. Differential receive input pins for 100FX, 100BASE-TX, or 10BASE-T.
33
RX+ I Receive Input: Differential receive input pin for 100FX, 100BASE-TX, or 10BASE-T.
34
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 GND Gnd Ground.
36 GND Gnd Ground.
37 REXT I External resistor (6.49kW ) connects to REXT and GND.
38 VDDRCV P
Analog 2.5V power supply. 2.5V power output of voltage regulator. See “Circuit Design
Ref. for Power Supply” section for details.
39 GND Gnd Ground.
40 TX- O Transmit Outputs: Differential transmit output for 100FX, 100BASE-TX, or 10BASE-T.
41 TX+ O Transmit Outputs: Differential transmit output for 100FX, 100BASE-TX, or 10BASE-T.
42 VDDTX P
Transmitter 2.5V power supply. See “Circuit Design Ref. for Power Supply” section for
details.
43 GND Gnd Ground.