adm6993 Infineon Technologies Corporation, adm6993 Datasheet - Page 26

• Manufacturer Part Number: adm6993
• Description: Adm6993/x Hdlc To Fast Ethernet Converter
• Manufacturer: Infineon Technologies Corporation

3.3.7
IPG is the idle time between any two successive packets from the same port. The typical number is 96-bits time.
The value is 9.6µs for 10Mbps ETHERNET, and 960ns for 100Mbps fast ETHERNET. ADM6993/X provides the
option of a 92-bit gap in EEPROM to prevent packet lost when Flow Control is turned off and clock P.P.M. value
differs.
3.3.8
The ADM6993/X will discard all illegal frames such as runt packet (less than 64 bytes), oversize packet (greater
than 1518 or 1522 bytes) and bad CRC. Dribbling packing with good CRC value will accept by ADM6993/X. In
case of bypass mode enabled, ADM6993/X will support tagged up to 1522bytes, and untagged packets up to 1518
bytes. In case of non-bypass mode, ADM6993/X will support tagged packets up to 1522 bytes, and untagged
packets up to 1518 bytes.
3.3.9
Back Pressure function is supported for half-duplex operation. When the ADM6993/X cannot allocate a receiving
buffer for an incoming packet (buffer full), the device will transmit a jam pattern on the port, thus forcing a collision.
Back Pressure is enabled by the BPEN set during RESET asserting. An Infineon-ADMtek Co Ltd proprietary
algorithm is implemented inside the ADM6993/X to prevent back pressure function causing HUB partitioned under
heavy traffic environment and reduce the packet lost rate to increase the whole system performance.
3.3.10
When full duplex port runs out of its receiving buffer, a PAUSE packet command will be issued by ADM6993/X to
notice the packet sender to pause the transmission. This frame based flow control is totally compliant to IEEE
802.3x. ADM6993/X can issue or receive pause packet.
3.3.11
If Broadcast Storming filter is enable, the broadcast packets over the rising threshold within 50 ms will be discarded
by the threshold setting. See EEPROM Reg.5
Broadcast storm mode after initial:
Time interval: 50 ms
The max. packet number = 7490 in 100Base, 749 in 10Base
Table 14
Per Port Rising Threshold
All 100TX
Not All 100TX
Per Port Falling Threshold
All 100TX
Not All 100TX
Data Sheet
Inter-Packet Gap (IPG)
Illegal Frames
Half Duplex Flow Control
Full Duplex Flow Control
Broadcast Storm Filter
Port Rising/Falling Threshold
00
Disable
Disable
00
Disable
Disable
01
10%
1%
01
5%
0.5%
H
.
26
10
20%
2%
10
10%
1%
Function Description
Rev 1.11, 2005-11-28
11
40%
4%
11
20%
2%
ADM6993/X