Datasheet

KSZ8721BL/SL
DS00002813A-page 8  2018 Microchip Technology Inc.
Note 2-1 P = Power supply;
GND = Ground;
I = Input; O = Output; I/O = Bi-directional;
IPU/O = Input with internal pull-up during power-up/reset; output pin otherwise.
IPU = Input with internal pull-up.
IPD = Input with internal pull-down.
IPD/O = Input with internal pull-down during reset; output pin otherwise.
IPU/O = Input with internal pull-up during reset; output pin otherwise.
30 PD# IPU Power Down. 1 = Normal operation, 0 = Power-down. Active low.
31 VDDRX P
Analog 2.5V power supply. See
Section 3.23 “Circuit Design
Reference 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 Section 3.21 “100BT FX
Mode” for more details.
35 GND GND Ground.
36 GND GND Ground.
37 REXT I External resistor (6.49 kW) connects to REXT and GND.
38 VDDRCV P
Analog 2.5V power supply. 2.5V power output of voltage regulator.
See
Section 3.23 “Circuit Design Reference for Power Sup-
ply”
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
Section 3.23 “Circuit
Design Reference for Power Supply”
for details.
43 GND GND Ground.
44 GND GND Ground.
45 XO O XTAL feedback: Used with XI for Xtal application.
46 XI I
Crystal Oscillator Input: Input for a crystal or an external 25 MHz
clock. If an oscillator is used, XI connects to a 3.3V tolerant oscil-
lator, and X2 is a no-connect.
47 VDDPLL P
Analog PLL 2.5V power supply. See
Section 3.23 “Circuit
Design Reference for Power Supply”
for details.
48 RST# IPU Chip Reset. Active low, minimum of 50 µs pulse is required.
TABLE 2-1: PIN DESCRIPTION (CONTINUED)
Pin
Number
Pin Name
Type
(Note 2-1)
Description