PLX Technology PEX 8505, Hardware Reference Manual

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PEX 8505RDK Hardware Reference Manual v1.1
8 © 2007, PLX Technology, Inc. All rights reserved.
Figure 2-4. PEX 8505RDK Power Subsystem
2.8.2 Power Sequencing
The PEX 8505 device requires that the 1.0V power rails are supplied before the 1.5V and 3.3V rails are
powered. This power sequencing is accomplished via three bipolar transistors (Q3, Q4, Q6), biasing
resistors and one power MOSFET (Q5).
2.9 LED Indicators
The PEX 8505RDK provides a number of LED indicators including power-on indication, PEX 8505 lane
status indication, and Hot Plug status indication. Table 2-1 provides a quick explanation of the various
board indicators.
Table 2-1. PEX 8505RDK LED Indicator descriptions
Indicator
Type
Locations LED On LED Off
Board Power
indication
D16, D15, D17, D18 1.0V, 1.5V, 12V, 3.3V power on
1.0V, 1.5V, 12V,
3.3V power off
Slot J1 Power
Fault
D14
+12V or +3.3V power to slot J1 had
dropped below -15% on either supply.
+12V and +3.3V power
to slots J1 is good.
J5 Power
indication
D20
ATX Hard disk connector is currently
supplying power
ATX hard disk
connector is not
supplying power
+12V
+3.3V
PCI Express Card Edge
3.3V-to-1V
LDO Regulator
3.3V-to-
1.5V LDO
Pwr
Seq.
PEX_VTT
VDD10/VDD10S/VDD10A
VDD33/VDD33A
PEX 8505
ATX HD Conn.
5V-to-3.3V
DC/DC
+12V
+5V
+3.3V
ATX HD Conn.
5V-to-3.3V
DC/DC
+12V
+5V
+3.3V
PCI
E
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PC
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PC
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RDK Port Expander
P
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PCI Express Straddle Mount Connector