KS8721B A4 Micrel Inc, KS8721B A4 Datasheet - Page 14

• Manufacturer Part Number: KS8721B A4
• Manufacturer: Micrel Inc

Specifications of KS8721B A4

• Lead Free Status / RoHS Status: Not Compliant

Transmit Data [1:0] (TXD[1:0])
Transmit Data TXD[1:0] shall transition synchronously with respect to REF_CLK. When TX_EN is asserted, TXD[1:0] are
accepted for transmission by the PHY. TXD[1:0] shall be “00” to indicate idle when TX_EN is de-asserted. Values of TXD[1:0]
other than “00” when TX_EN is de-asserted are reserved for out-of-band signalling (to be defi ned). Values other than “00”
on TXD[1:0] while TX_EN is deasserted shall be ignored by the PHY.
Collision Detection
Since the defi nition of CRS_DV and TX_EN both contain an accurate indication of the start of frame, the MAC can reliably
regenerate the COL signal of the MII by ANDing TX_EN and CRS_DV.
During the IPG time following the successful transmission of a frame, the COL signal is asserted by some transceivers as a
self-test. The Signal Quality Error (SQE) function will not be supported by the reduced MII due to the lack of the COL signal.
Historically, SQE was present to indicate that a transceiver located physically remote from the MAC was functioning. Since
the reduced MII only supports chip-to-chip connections on a PCB, SQE functionality is not required.
RX_ER
The PHY shall provide RX_ER as an output according to the rules specifi ed in IEEE 802.3u [2] (see Clause 24, Figure 24-
11 - Receive State Diagram). RX_ER shall be asserted for one or more REF_CLK periods to indicate that an error (e.g. a
coding error or any error that a PHY is capable of detecting, and that may otherwise be undetectable by the MAC sublayer)
was detected somewhere in the frame presently being transferred from the PHY. RX_ER shall transition synchronously with
respect to REF_CLK. While CRS_DV is de-asserted, RX_ER shall have no effect on the MAC.
RMII AC Characteristics
RMII Transmit Timing
M9999-030106
Symbol
Symbol
Symbol
Symbol
Symbol
Symbol
t
t
t
t
Parameter
Parameter
Parameter
Parameter
Parameter
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
TXEN, TXD[1:0], TX_EN, Data Setup to REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data Setup to REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data Setup to REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data Setup to REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data Setup to REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data Setup to REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data hold from REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data hold from REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data hold from REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data hold from REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data hold from REF_CLK rising edge
TXEN, TXD[1:0], TX_EN, Data hold from REF_CLK rising edge
SU
H
Parameter
Parameter
Parameter
Parameter
Parameter
Parameter
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Frequency
REF_CLK Duty Cycle
REF_CLK Duty Cycle
REF_CLK Duty Cycle
REF_CLK Duty Cycle
REF_CLK Duty Cycle
REF_CLK Duty Cycle
REF_CLK Duty Cycle
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RX_ER Data Set-Up to REF_CLK Rising
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RX_ER Data Set-Up to REF_CLK Rising
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RX_ER Data Set-Up to REF_CLK Rising
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RX_ER Data Set-Up to REF_CLK Rising
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RX_ER Data Set-Up to REF_CLK Rising
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RX_ER Data Set-Up to REF_CLK Rising
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RXER Data Hold from REF_CLK
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RXER Data Hold from REF_CLK
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RXER Data Hold from REF_CLK
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RXER Data Hold from REF_CLK
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RXER Data Hold from REF_CLK
TXD[1:0]. TX_EN, RXD[1:0], CRS_DV, RXER Data Hold from REF_CLK
Rising Edge
Rising Edge
Rising Edge
REF_CLK
RXD[1:0]
RXDV
RXER
t
od
20ns
14
Min
Min
Min
Min
Min
Min
Min
Min
Min
Min
Min
35
35
35
35
35
35
35
4
4
4
4
4
4
2
2
2
2
2
2
4
4
4
4
4
4
2
2
2
2
2
2
Typ
Typ
Typ
Typ
Typ
Typ
Typ
Typ
Typ
Typ
Typ
50
50
50
50
50
50
50
50
50
50
50
50
50
Max
Max
Max
Max
Max
Max
Max
Max
Max
Max
Max
65
65
65
65
65
65
65
March 2006
Units
Units
Units
Units
Units
Units
Units
Units
Units
Units
Units
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
%
%
%
%
%
%
%