KSZ8721BLA4TR Micrel Semiconductor, Inc., KSZ8721BLA4TR Datasheet - Page 15

• Manufacturer Part Number: KSZ8721BLA4TR
• Description: IC PHY 1CH 10/100MBPS 48LQFP T/R
• Manufacturer: Micrel Semiconductor, Inc.

RMII Receive Timing
Auto Crossover (Auto MDI/MDI-X)
Automatic MDI/MDI-X configuration is intended to eliminate the need for crossover cables between similar devices.
The assignment of pin-outs for a 10/100 BASE-T crossover function cable is shown below.
This feature can eliminate the confusion in real applications so both straight cable and crossover cable can be used.
This feature is controlled by register 1f:13. See “Register 1fh–100BaseTX PHY Controller” section for details.
April 2005
KS8721B/BT
Parameter
REF_CLK Frequency
RXD[1:0], CRS_DV, RX_ER Output delay from REF_CLK rising edge
REF_CLK
RXD[1:0]
RXDV
RXER
Modular Connector (RJ45)
10/100 Base-T
Media Dependent Interface
10/100 BASE-T
Media Dependent Interface
Receive Pair
Transmit Pair
(Repeater or Switch)
Transmit Pair
Receive Pair
Modular Connector
(RJ45)
HUB
NIC
Figure 1. Straight Through Cable
Figure 2. Crossover Cable
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
t
od
20ns
15
10/100 Base-T
Media Dependent Interface
10/100 Base-T
Media Dependent Interface
Modular Connector (RJ45)
(Repeater or Switch)
(Repeater or Switch)
Modular Connector
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
(RJ45)
Transmit Pair
HUB
Receive Pair
Transmit Pair
HUB
Receive Pair
Min
2.8
Typ
50
Max
10
M9999-041405
Micrel, Inc.
Units
MHz
ns