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Important Information
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1.5 Important Information
This section clarifies important system implementation.
1.5.1 G_RST Clamping Rail
G_RST is clamped to V
CCP
, so removing V
CCP
causes assertion of G_RST.
Figure 1–7.
G_RST and V
CCP
Relationship
V
CCP
G_RST
V
CCP
= 0
V
CCP
removed
G_RST
All other signals with clamping rails behave the same way.
1.5.2 PME/RI_OUT Bit Definition
If PME is selected, only PME is signaled on the PME/RI_OUT terminal. If
RI_OUT
is selected, only RI_OUT is signaled. The PCI445X device can signal
PME and RI_OUT as completely separated signals. In this case RI_OUT
should be assigned on the MFUNC terminal.
1.5.3 Serialized IRQ Data Stream
PCI clock is needed for operation of the PCI445X serialized IRQ
state-machine. During SUSPEND assertion, the PCI445X device stops the
IRQSER stream. Before asserting SUSPEND, IRQSER must be stopped.
1.5.4 Socket Power Control
An internal or external CLOCK source is needed for the socket power control
through the P
2
C interface. The internal ring oscillator is on while the core V
CC
is applied to the PCI445X device. External CLOCK source is dependent on the
system.
1.5.5 External CLOCK Frequency for P
2
C Interface
If an external P
2
C CLOCK is used, then it will affect:
- Advanced CD line noise filtering
- VS test speed
- TPS22X6 power control interface speed
Use of the internal ring oscillator is recommended. Recommended external
CLOCK source is the 32.768-kHz real-time clock (RTC).