PEX 8509RDK Hardware Reference Manual v1.1
© 2007, PLX Technology, Inc. All rights reserved.
7
Figure 2-4. PEX 8509RDK Power Subsystem
2.9.2 Power
Sequencing
The PEX 8509 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).
2.10 LED
Indicators
The PEX 8509RDK provides a number of LED indicators including power-on indication, PEX 8509 lane
status indication, and Hot Plug status indication. Table 2-1 provides a quick explanation of the various
board indicators.
Table 2-1. PEX 8509RDK 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/J2/J3
Power Fault
D14
+12V or +3.3V power to slots J1/J2/J3
had dropped below -15% on either
supply.
+12V and +3.3V
power to slots
J1/J2/J3 is good.
J5 Power
indication
D20
ATX Hard disk connector is currently
supplying power
ATX hard disk
connector is not
supplying power
PC
I Express
S
lo
t
C
onn
ec
to
r
PC
I Express
S
lo
t
C
onn
ec
to
r
+12V
+3.3V
+3.3Vaux
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 8509
ATX HD Conn.
5V-to-3.3V
DC/DC
+12V
+5V
Hot Plug
Pwr. Ctl.
PCI Exp
res
s
St
ra
ddl
e Mount
Con
n
ect
or
PC
I E
xpress
S
lot
C
onne
c
tor
