Compaq SMA200 5.4.7. SMBus

DIGITAL-LOGIC AG SMA200 Manual V1.0
31
5.4.7. SMBus
Signal BUS Type Description
On Module
Termination
Ext. Ter-
mination
Needed
Max.
Length
in mm
Ohm
Matched
Length
in mm
SMB_ALERT# CMOS 3.3V
In
Connect to the SMB device PU 10k to
3.3V
- 200 55 -
SMB_DATA CMOS 3.3V
I/O
Connect to the SMB device
open drain
PU 4.7k to
3.3V
- 200 55 -
SMB_CLOCK CMOS 3.3V
I/O
Connect to the SMB device
open drain
PU 4.7k to
3.3V
- 200 55 -
If the signals are not used:
The pins can stay open.
Remarks:
The SMB_ALERT# may be used to initiate an SMB event over APIC or an SMI.
Maximum BUS capacitance is 200pF. For higher BUS loads, the SMB repeater PCA9515 from Philips
is recommended. Each new SMB segment must be terminated with 2x 4.7k.
EMV/EMI filters:
Are not needed.