KSZ8721B Micrel Inc, KSZ8721B Datasheet - Page 14

• Manufacturer Part Number: KSZ8721B
• Description: IC TXRX PHY 10/100 2.5V 48-SSOP
• Manufacturer: Micrel Inc
• Type: Transceiverr

Specifications of KSZ8721B

• Number Of Drivers/receivers: 1/1
• Protocol: MII, RMII
• Voltage - Supply: 2.375 V ~ 2.625 V
• Mounting Type: Surface Mount
• Package / Case: 48-SSOP
• Data Rate: 100Mbps
• Supply Voltage Range: 2.375V To 2.625V
• Logic Case Style: SSOP
• No. Of Pins: 48
• Operating Temperature Range: 0°C To +70°C
• Msl: MSL 2 - 1 Year
• Ic Function: Transceiver IC
• Termination Type: SMD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 576-1627 - BOARD EVALUATION FOR KSZ8721BMC576-1626 - BOARD EVALUATION FOR KSZ8721BL
• Lead Free Status / RoHS Status: Compliant, Lead free / RoHS Compliant
• Other names: 576-1026-5; 576-1510-5; 576-1510-5; KSZ8721B

KS8721B/BT
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 defined). Values other than “00” on
TXD[1:0] while TX_EN is deasserted shall be ignored by the PHY.
Collision Detection
Since the definition 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 specified 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
M9999-041405
Symbol
t
t
Parameter
REF_CLK Frequency
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
SU
H
Parameter
REF_CLK Frequency
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, RXER Data Hold from REF_CLK
Rising Edge
REF_CLK
TXD[1:0]
TXEN
TXER
20ns
t
1
t
2
14
Min
Min
35
4
2
4
2
Typ
Typ
50
50
Max
Max
65
Micrel, Inc.
April 2005
Units
Units
MHz
MHz
ns
ns
ns
ns
%