ax88790 ASIX Electronics Corporation, ax88790 Datasheet - Page 41

• Manufacturer Part Number: ax88790
• Description: Pcmcia 10/100m Fast Ethernet Controller With Embedded Phy
• Manufacturer: ASIX Electronics Corporation

6.4 A.C. Timing Characteristics
6.4.1 XTAL / CLOCK
LCLK/XTALIN
CLKO
6.4.2 Reset Timing
LCLK
RESET
Note: Some chips may need long power down for successful PHY auto negotiation
Tcyc
Thigh
Tlow
Tr/Tf
Tod
Symbol
Symbol
Trst
Root of cause:
The PHY inside of AX88790 has a special request due to the semiconductor’s process. Namely,
it needs a very long power down for successful Auto Negotiation for some chips. We made a test
in lab and found it would be no problem if the PHY's initial time kept for 2 sec for all chips. If the
power down is less then this number, some of the PHY's Auto Negotiation will not be complete
and there will be potential to cause the link fail. If the auto negotiation time is not long enough,
uncertain numbers of chip may not work properly.
Countermeasure:
Following actions on chip initialization will fix the problem of long auto negotiation.
CYCLE TIME
CLK HIGH TIME
CLK LOW TIME
CLK SLEW RATE
LCLK/XTALIN TO CLKO OUT DELAY
Reset pulse width
1. Set the PHY register MR0 with 0x800h (1000,0000,0000) -- bit 11 of MR0 to '1'
2. Wait for 2.5 sec
AX88790 L
(Power down Mode).
Tr
Tod
Description
Description
Thigh
Tf
Tcyc
3-in-1 PCMCIA Fast Ethernet Controller
Tlow
41
Min
Min
100
16
16
1
ASIX ELECTRONICS CORPORATION
Typ.
Typ.
40
20
20
10
-
-
Max
Max
24
24
4
-
Units
Units
LClk
ns
ns
ns
ns