LAN9303-ABZJ SMSC, LAN9303-ABZJ Datasheet - Page 82
![IC ETHER SW 3PORT 16BIT 56QFN](/photos/29/2/290201/lan9303_sml.jpg)
LAN9303-ABZJ
Manufacturer Part Number
LAN9303-ABZJ
Description
IC ETHER SW 3PORT 16BIT 56QFN
Manufacturer
SMSC
Specifications of LAN9303-ABZJ
Controller Type
Ethernet Switch Controller
Interface
SMBus (2-Wire/I²C)
Voltage - Supply
3 V ~ 3.6 V
Current - Supply
190mA
Operating Temperature
0°C ~ 70°C
Mounting Type
Surface Mount
Package / Case
56-QFN
Product
Ethernet Switches
Standard Supported
Yes
Data Rate
10 Mbps/100 Mbps
Supply Voltage (max)
3.6 V
Supply Voltage (min)
3 V
Supply Current (max)
0.19 A (Typ)
Maximum Operating Temperature
+ 70 C
Minimum Operating Temperature
0 C
Mounting Style
SMD/SMT
For Use With
638-1095 - EVALUATION BOARD FOR LAN9303
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Other names
638-1082
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LAN9303-ABZJ
Manufacturer:
MICROCHIP/微芯
Quantity:
20 000
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Revision 1.4 (07-07-10)
6.4.11
6.5
6.5.1
6.5.1.1
6.5.2
Counters
A counter is maintained per port that contains the number of MAC address that were not learned or
were overwritten by a different address due to MAC Address Table space limitations. These counters
are accessible via the following registers:
A counter is maintained per port that contains the number of packets filtered at ingress. This count
includes packets filtered due to broadcast throttling, but does not include packets dropped due to
ingress rate limiting. These counters are accessible via the following registers:
The Buffer Manager (BM) provides control of the free buffer space, the multiple priority transmit
queues, transmission scheduling, and packet dropping. VLAN tag insertion and removal is also
performed by the Buffer Manager. The following sections detail the various features of the Buffer
Manager.
Packet Buffer Allocation
The packet buffer consists of 32KB of RAM that is dynamically allocated in 128 byte blocks as packets
are received. Up to 16 blocks may be used per packet, depending on the packet length. The blocks
are linked together as the packet is received. If a packet is filtered, dropped, or contains a receive
error, the buffers are reclaimed.
Buffer Limits and Flow Control Levels
The BM keeps track of the amount of buffers used per each ingress port. These counts are used to
generate flow control (half-duplex backpressure or full-duplex pause frames) and to limit the amount
of buffer space that can be used by any individual receiver (hard drop limit). The flow control and drop
limit thresholds are dynamic and adapt based on the current buffer usage. Based on the number of
active receiving ports, the drop level and flow control pause and resume thresholds adjust between
fixed settings and two user programmable levels via the
(BM_DROP_LVL),
Buffer Manager Flow Control Resume Level Register (BM_FC_RESUME_LVL)
The BM also keeps a count of the number of buffers that are queued for multiple ports (broadcast
queue). This count is compared against the
(BM_BCST_LVL), and if the configured drop level is reached or exceeded, subsequent packets are
dropped.
Random Early Discard (RED)
Based on the ingress flow monitoring detailed in
on page
if the
Yellow
randomly discarded based on the moving average number of buffers used by the ingress port.
Buffer Manager (BM)
Switch Engine Port 0 Learn Discard Count Register (SWE_LRN_DISCRD_CNT_0)
Switch Engine Port 1 Learn Discard Count Register (SWE_LRN_DISCRD_CNT_1)
Switch Engine Port 2 Learn Discard Count Register (SWE_LRN_DISCRD_CNT_2)
Switch Engine Port 0 Ingress Filtered Count Register (SWE_FILTERED_CNT_0)
Switch Engine Port 1 Ingress Filtered Count Register (SWE_FILTERED_CNT_1)
Switch Engine Port 2 Ingress Filtered Count Register (SWE_FILTERED_CNT_2)
Drop on Red
bit in the
75, packets are colored as Green, Yellow, or Red. Packets colored Red are always discarded
Buffer Manager Configuration Register (BM_CFG)
Buffer Manager Flow Control Pause Level Register
bit in the
Small Form Factor Three Port 10/100 Managed Ethernet Switch with Single MII/RMII/Turbo MII
Buffer Manager Configuration Register (BM_CFG)
DATASHEET
82
Buffer Manager Broadcast Buffer Level Register
Section 6.4.6, "Ingress Flow Metering and Coloring,"
Buffer Manager Drop Level Register
is set, packets colored Yellow are
(BM_FC_PAUSE_LVL), and
SMSC LAN9303/LAN9303i
respectively.
is set. If the
Datasheet
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