KSZ8081RNACA-TR Datasheet, PDF (9/51 Pages) Micrel Semiconductor – 10Base-T/100Base-TX PHY with RMII Support

Micrel, Inc.
KSZ8081RNA/KSZ8081RND
Pin Description
Pin Number
Pin Name
Type⁽¹⁾ Pin Function
1.2V core VDD (power supplied by KSZ8081RNA/KSZ8081RND)
1
VDD_1.2
P
Decouple with 2.2µF and 0.1µF capacitors to ground.
2
VDDA_3.3
P
3.3V analog VDD
3
RXM
I/O
Physical receive or transmit signal (− differential)
4
RXP
I/O
Physical receive or transmit signal (+ differential)
5
TXM
I/O
Physical transmit or receive signal (− differential)
6
TXP
I/O
Physical transmit or receive signal (+ differential)
Crystal feedback for 25MHz crystal
7
XO
O
This pin is a no connect if an oscillator or external clock source is used.
RMII – 25MHz Mode: 25MHz ±50ppm Crystal / Oscillator / External Clock Input
RMII – 50MHz Mode: 50MHz ±50ppm Oscillator / External Clock Input
For unmanaged mode (power-up default setting),
8
XI
I
KSZ8081RNA takes in the 25MHz crystal/clock on this pin.
KSZ8081RND takes in the 50MHz clock/on this pin.
After power-up, both the KSZ8081RNA and KSZ8081RND can be programmed to
either the 25MHz mode or 50MHz mode using PHY register 1Fh bit [7].
See also REF_CLK (pin 16).
Set PHY transmit output current
9
REXT
I
Connect a 6.49kΩ resistor to ground on this pin.
Management Interface (MII) Data I/O
10
MDIO
Ipu/Opu _{This pin has a weak pull-up, is open-drain, and requires an external 1.0kΩ}
pull-up resistor.
Management Interface (MII) Clock input
11
MDC
Ipu
This clock pin is synchronous to the MDIO data pin.
12
RXD1
Ipd/O RMII Receive Data Output[1]⁽²⁾
13
RXD0
Ipu/O RMII Receive Data Output[0]⁽²⁾
14
VDDIO
P
3.3V, 2.5V, or 1.8V digital VDD
RMII Mode:
Carrier Sense/Receive Data Valid output /
15
CRS_DV /
PHYAD[1:0]
Ipd/O
Config Mode:
The pull-up/pull-down value is latched as PHYAD[1:0] at the
de-assertion of reset.
See the “Strapping Options” section for details.
Note:
1. P = Power supply.
Gnd = Ground.
I = Input.
O = Output.
I/O = Bi-directional.
Ipu = Input with internal pull-up (see “Electrical Characteristics” for value).
Ipu/O = Input with internal pull-up (see “Electrical Characteristics” for value) during power-up/reset; output pin otherwise.
Ipd/O = Input with internal pull-down (see “Electrical Characteristics” for value) during power-up/reset; output pin otherwise.
Ipu/Opu = Input with internal pull-up (see “Electrical Characteristics” for value) and output with internal pull-up (see “Electrical Characteristics” for
value).
February 6, 2014
9
Revision 1.1