KSZ8993M A5 Micrel Inc, KSZ8993M A5 Datasheet - Page 31
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KSZ8993M A5
Manufacturer Part Number
KSZ8993M A5
Description
Manufacturer
Micrel Inc
Datasheet
1.KSZ8993M_A5.pdf
(86 pages)
Specifications of KSZ8993M A5
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
Compliant
sending 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 KSZ8993M 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 KSZ8993M 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 KSZ8993M 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.
October 2008
KSZ8993M 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
KSZ8993M
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
Collision detection
Receive data valid
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
31
KSZ8993M MAC-Mode Connections
External
PHY Signals
MTXEN
MTXER
MTXD3
MTXD2
MTXD1
MTXD0
MTXC
MCOL
MCRS
MRXDV
MRXER
MRXD3
MRXD2
MRXD1
MRXD0
MRXC
KSZ8993M
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
M9999-020606
KSZ8993M/ML