KSZ8873MLL AM Micrel Inc, KSZ8873MLL AM Datasheet - Page 24
![IC ETHERNET SWITCH 3PORT 64-LQFP](/photos/6/81/68149/64-lqfp-micrel_sml.jpg)
KSZ8873MLL AM
Manufacturer Part Number
KSZ8873MLL AM
Description
IC ETHERNET SWITCH 3PORT 64-LQFP
Manufacturer
Micrel Inc
Specifications of KSZ8873MLL AM
Controller Type
Ethernet Switch Controller
Interface
MII
Voltage - Supply
1.8V, 2.5V, 3.3V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
64-LQFP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Current - Supply
-
Lead Free Status / RoHS Status
Not Compliant, Lead free / RoHS Compliant
Other names
576-3633
KSZ8873MLL AM
KSZ8873MLLAM
KSZ8873MLL AM
KSZ8873MLLAM
Micrel, Inc.
KSZ8873MLL/FLL/RLL
Hardware Power Down
KSZ8873 supports a hardware power down mode. When the pin PWRDN is actived low, the entire chip is powered down.
Functional Overview: MAC and Switch
Address Lookup
The internal lookup table stores MAC addresses and their associated information. It contains a 1K unicast address table
plus switching information.
The KSZ8873MLL/FLL/RLL is guaranteed to learn 1K addresses and distinguishes itself from hash-based lookup tables,
which depending on the operating environment and probabilities, may not guarantee the absolute number of addresses it
can learn.
Learning
The internal lookup engine updates its table with a new entry if the following conditions are met:
1. The received packet's Source Address (SA) does not exist in the lookup table.
2. The received packet is good; the packet has no receiving errors, and is of legal length.
The lookup engine inserts the qualified SA into the table, along with the port number and time stamp. If the table is full, the
last entry of the table is deleted to make room for the new entry.
Migration
The internal lookup engine also monitors whether a station has moved. If a station has moved, it will update the table
accordingly. Migration happens when the following conditions are met:
1. The received packet's SA is in the table but the associated source port information is different.
2. The received packet is good; the packet has no receiving errors, and is of legal length.
The lookup engine will update the existing record in the table with the new source port information.
Aging
The lookup engine updates the time stamp information of a record whenever the corresponding SA appears. The time
stamp is used in the aging process. If a record is not updated for a period of time, the lookup engine removes the record
from the table. The lookup engine constantly performs the aging process and will continuously remove aging records. The
aging period is about 200 seconds. This feature can be enabled or disabled through register 3 (0x03) bit [2].
Forwarding
The KSZ8873MLL/FLL/RLL forwards packets using the algorithm that is depicted in the following flowcharts. Figure 4
shows stage one of the forwarding algorithm where the search engine looks up the VLAN ID, static table, and dynamic
table for the destination address, and comes up with “port to forward 1” (PTF1). PTF1 is then further modified by
spanning tree, IGMP snooping, port mirroring, and port VLAN processes to come up with “port to forward 2” (PTF2), as
shown in Figure 5. The packet is sent to PTF2.
September 2010
24
M9999-092309-1.2