PLX Technology PEX 8311RDK, Hardware Reference Manual

Page: 19 / 66

PEX 8311RDK Hardware Reference Manual, Version 0.90
© 2005 PLX Technology, Inc. All rights reserved.
11
3.4.2.1 Reset Circuitry
The reset pushbutton (SW1) allows the user to force the PEX 8311 PERST# signal low. This causes a full
reset of the device and the local bus logic. Pressing the reset button causes LRESET# to be asserted and
will cause all EEPROM values to be re-loaded.
Pressing the pushbutton reset will also clear all configuration registers including the PCI Express
configuration registers. The PEX 8311 will have to be re-enumerated by the host before it will respond to
PCI Express memory transactions.
3.5 LED Indicators
The PEX 8311RDK provides several LED indicators, including power-on indication and programmable
PEX 8311 GPIO lane status indication. Table 3-4 provides a quick explanation of each LED indicators.
By default GPIO[3:1] are configured as inputs and pulled high and GPIO0 shows the link status. By
changing GPIOCTL[13:12] in the SPI EEPROM (U2) the GPIO lines can be reconfigured to reflect the
lower four bits of the LTSSM state machine. See the PEX8311 data book for additional details.
Table 3-4. PEX 8311RDK LED Indicators
Indicator Type Location LED ON
LED5 PCI Express 12V power on
LED6 3.3V power is on Board Power Indication
LED8 2.5V power is on
GPIO0 LED1
Output
OFF (0) – Link Down
ON (1) – Link Up
GPIO1 LED2 ON, GPIO1 = Input by default
GPIO2 LED3 ON, GPIO2 = Input by default
GPIO3 LED4 ON, GPIO3 = Input by default
3.6 PEX 8311RDK Power
The PEX 8311RDK has two sources for DC power. The first source is the card edge connector (P1). This
x1 connector provides up to 500 mA at +12V
DC
, and 3.0A at +3.3V
DC
. Card edge power is intended to
power only PEX 8311RDK components.
The second source, the ATX 4-pin connector (J4), pr12V
DC
, and the +5V
DC
power supplied to
the POM connector.
The electronic devices on the RDK r1.5V, +2.5V, and +3.3V DC power. A 5A LDO regulator (U4)
is used to convert the PCI E12 V
DC
to +3.3 V
DC
, a 2.5A LDO regulator (U9) is used to convert
the PCI E3.3 V
DC
to +2.5 V
DC
and a 250mA regulator (U3) is used to convert the PCI Express
+3.3 V
DC
to +1.5 V
DC
power for the on board devices. As long as the output current from the voltage
converter remains less than the maximum current outputs from the LDOs, the RDK board will function
correctly.
3.6.1 PEX 8311 Bridge Device Power
The PEX 8311 bridge device power requires the following:
ƒ
VDD Core +1.5 V
DC
±10%
ƒ +2.5 V
DC
±10%
ƒ VDD I/O +3.3 V
DC
±10%
Care must be taken to ensure that the power sequencing requirements of the PEX 8311 are met – please
refer to the PEX 8311 data book for further details.
As shipped the absolute maximum current required for the PEX 8311RDK supplies is detailed in Table
3-5.