Smb Routing Guidelines; Smb Trace Length Guidelines; Table 38: Smb Trace Length Guidelines; Figure 32: Topology For Smb - Advantech SOM-5992 Design Manual

2.13.2 SMB Routing Guidelines

The SMBus should be connected to all or none of the PCIe devices and slots. A general
recommendation is to not connect these devices to the SMBus.
The maximum load of SMBus lines is limited to 3 external devices. Please contact Advantech if more
devices are required.
Contact Advantech for a list of SMBus addresses used on the Module. Do not use the same address for
Carrier located devices.

2.13.3 SMB Trace Length Guidelines

Figure 32 : Topology for SMB
Table 38 : SMB Trace Length Guidelines
Parameter
Signal Group
Single End
Nominal Trace Space within SPI
Signal Group
Spacing to Other Signal Group
LA
LB
Max length of LA+LB
Length Mismatch
Via Usage
Notes:
Main Route Guidelines
SMB
50Ω ±15%
Min. 10mils
Min. 10mils
Please see the SOM-5992 Layout Checklist
Carrier Board Length
24"
NA
Try to minimize number of vias
１０５
Notes