8
Tsi340 Evaluation Board User Manual
80E3000_MA002_02
Integrated Device Technology
www.idt.com
The system user must limit its total power consumption to 25W budget from all power rails on the
primary finger connector based on PCI specification
2.4.1.1
Optional ATX Power Connector
If the total power requirement of plug-in cards exceed the current draw as indicated in
Table 3
, an
auxiliary ATX power supply may be used to augment the power capacity of the system. The bridge
board has an ATX power supply connector assembly option.
The ATX connector is usually not installed.
2.4.2
Tsi340 Core Voltage Isolation
The Tsi340 supply voltage plane on the PCB can be isolated from the board’s 3.3 V plane. This feature
is used to evaluate the current draw of the PCI bridge. The connection from the Tsi340 supply to the
board 3.3 V is done through three 0 Ohm resistors: R5, R6, R7. Current measurement can be done by
removing the resistors and insert an amp meter between the resistor pads on the PCB.
2.4.3
PRSNT Pin Power Setting on Primary PCI
The finger connector PRSNT[1:2] pins are wired to indicate a power requirement of 25 W. This is the
maximum power the PRSNT[1:2] pins can indicate for an add-in card. The PRSNT pin on the
secondary side connectors is not used.
Table 3: Maximum Current Draw Per Rail
Rail
Current
Power
-12V
100 mA
1.2 W
+12V
500 mA
6 W
5V
5 A
25 W
3.3V
7.6 A
25 W
3.3VAUX
375 mA
1.2 W
If the optional ATX power connector is used, the ATX power supply and PCI finger
connector supply must come from the same supply source.