PEX 8112 Fwd Riser Hardware Reference Manual for Board Revision 1.0
–
Version 1.1
Copyright © 2010 by PLX Technology, Inc. All rights reserved
5
3.3.1 PCI
Power
The PEX 8112 Fwd Riser provides four voltages to the PCI slot. These are:
•
3.3V derived from the PCI Express slot
•
5V supplied by way of the floppy disk power connector (J4)
•
+12V derived from the PCI Express edge slot or the floppy disk power connector (J4), by option resistor
•
-12V regulated on board from the 3.3V supply
3.4 PCI
Express
Interface
The PCI Express interface is a male card edge connector, based on the
PCI Express Card Electromechanical
(CEM) Specification, Revision 1.0a
for an x1 interface. The card edge pr12 VDC and +3.3 VDC, RefClk,
and PERST#. The PCI Express lanes are laid out as 100-Ohm, controlled-impedance, microstrip-differential pairs.
Trace length mismatch within signal pairs is not greater than 0.005".
3.4.1 RefClk
PCI Express RefClk enters the PEX 8112RFwd Riser through the PCI Express card edge (male) connector.
RefClk is laid out as a 100-Ohm, controlled-impedance, microstrip-differential pair. Trace length mismatch is not
greater than 0.005".
3.4.2 PERST#
PERST# is the fundamental Reset signal to the PEX 8112, from the PCI Express edge connector.
3.5 LED
Indicators
The PEX 8112 Fwd Riser provides several LED indicators, including power-on indication and programmable PEX
8112 GPIO lane status indication. Table 1 provides a quick explanation of each LED indicator.
Table 1. PEX 8112 Fwd Riser LED Indicator Function
Indicator Type
Location
LED ON
GPIO D1
Output
OFF (0) – Link Down
ON (1) – Link Up
3.6
PEX 8112 Fwd Riser Power
The PEX 8112 Fwd Riser has two sources for DC power. The first source is the card edge connector (J1). This x1
connector provides up to 500 mA at +12V, and 3.0A at +3.3V. Card edge power is intended to power only PEX
8112 Fwd Riser components, as well as optional PCI connector (J3).
The second source, the 4-pin floppy disk power connector, pr12V, -12V, and +5V DC power. The +5V is
converted down to +3.3V and -12V for slot J3 when configured as a 3.3V slot. The +12V power rail is used
directly.
3.6.1
PEX 8112 Bridge Device Power
The PEX 8112 bridge device power consists of the following:
VDD Core
+1.5 VDC ±0.1V
VDD I/O
+3.3 VDC ±10%
VIO Clamp
+5 VDC for 5V PCI
+3.3 VDC for 3.3V PCI
