KSZ8993M Micrel Inc, KSZ8993M Datasheet - Page 30

• Manufacturer Part Number: KSZ8993M
• Description: IC SWITCH 10/100 3PORT 128PQFP
• Manufacturer: Micrel Inc

Specifications of KSZ8993M

• Applications: *
• Mounting Type: Surface Mount
• Package / Case: 128-MQFP, 128-PQFP
• Number Of Primary Switch Ports: 3
• Internal Memory Buffer Size: 32
• Operating Supply Voltage (typ): 1.8/2.5/3.3V
• Fiber Support: Yes
• Integrated Led Drivers: Yes
• Phy/transceiver Interface: MII/SNI
• Power Supply Type: Analog/Digital
• Package Type: PQFP
• Data Rate (typ): 10/100Mbps
• Vlan Support: Yes
• Operating Temperature (max): 70C
• Operating Temperature (min): 0C
• Pin Count: 128
• Mounting: Surface Mount
• Jtag Support: No
• Operating Supply Voltage (max): 1.89/3.465V
• Operating Supply Voltage (min): 1.71/3.135V
• Power Dissipation: 800mW
• Supply Current: 0.1/0.19A
• Operating Temperature Classification: Commercial
• Data Rate: 100Mbps
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-1037

out packets and keeps other stations in carrier sense deferred state. If the port has packets to send during a
backpressure situation, the carrier sense type back pressure will be interrupted and those packets will be
transmitted instead. If there are no more packets to send, carrier sense type backpressure will be active again
until switch resources free up. If a collision occurs, the binary exponential back-off algorithm is skipped and carrier
sense is generated immediately, reducing the chance of further colliding and maintaining carrier sense to prevent
reception of packets.
To ensure no packet loss in 10 BASE-T or 100 BASE-TX half duplex modes, the user must enable the following:
1. Aggressive back off (Global Register 3 (0x03), bit 0 or external strap-in pin SMAC = high)
2. No excessive collision drop (Global Register 4 (0x04), bit 3 or external strap-in pin SMAC = high)
These bits are not set as defaults because this is not the IEEE standard.
Broadcast Storm Protection
The KS8993M has an intelligent option to protect the switch system from receiving too many broadcast packets.
Broadcast packets will be forwarded to all ports except the source port, and thus use too many switch resources
(bandwidth and available space in transmit queues). The KS8993M has the option to include “multicast packets”
for storm control. The broadcast storm rate parameters are programmed globally, and can be enabled or disabled
on a per port basis. The rate is based on a 67ms interval for 100BT and a 500ms interval for 10BT. At the
beginning of each interval, the counter is cleared to zero, and the rate limit mechanism starts to count the number
of bytes during the interval. The rate definition is described in Global Register 6 (0x06) and 7 (0x07). The default
setting for registers 6 and 7 is 0x63, which is 99 decimal. This is equal to a rate of 1%, calculated as follows:
MII Interface Operation
The MII is specified by the IEEE 802.3 standards committee and provides a common interface between physical
layer and MAC layer devices. The MII Interface provided by the KS8993M is connected to the device’s third MAC.
The interface contains two distinct groups of signals: one for transmission and the other for reception. The
following table describes the signals used in the MII interface.
Micrel, Inc.
April 2005
KS8993M PHY-Mode Connections
External MAC
Controller Signals
MTXEN
MTXER
MTXD3
MTXD2
MTXD1
MTXD0
MTXC
MCOL
MCRS
MRXDV
MRXER
MRXD3
MRXD2
MRXD1
MRXD0
MRXC
148,800 frames/sec * 67ms/interval * 1% = 99 frames/interval (approx.) = 0x63
KS8993M
PHY Signals
SMTXEN
SMTXER
SMTXD[3]
SMTXD[2]
SMTXD[1]
SMTXD[0]
SMTXC
SCOL
SCRS
SMRXDV
(not used)
SMRXD[3]
SMRXD[2]
SMRXD[1]
SMRXD[0]
SMRXC
Pin
Descriptions
Table 3. MII Signals
Transmit data bit 3
Transmit data bit 2
Transmit data bit 1
Transmit data bit 0
Receive data valid
Collision detection
Receive data bit 3
Receive data bit 2
Receive data bit 1
Receive data bit 0
Transmit enable
Transmit clock
Transmit error
Receive clock
Carrier sense
Receive error
30
KS8993M MAC-Mode Connections
External
PHY Signals
MTXEN
MTXER
MTXD3
MTXD2
MTXD1
MTXD0
MTXC
MCOL
MCRS
MRXDV
MRXER
MRXD3
MRXD2
MRXD1
MRXD0
MRXC
KS8993M
MAC Signals
SMRXDV
(not used)
SMRXD[3]
SMRXD[2]
SMRXD[1]
SMRXD[0]
SMRXC
SCOL
SCRS
SMTXEN
SMTXER
SMTXD[3]
SMTXD[2]
SMTXD[1]
SMTXD[0]
SMTXC
KS8993M/ML/MI
M9999-041205