
IDT Clocking, Reset, and Initialization
Clock Operation
PES34H16 User Manual
3 - 9
October 30, 2008
Notes
Power Enable Controlled Reset Output
In this mode a downstream port reset output state is controlled as a side effect of slot power being
turned on or off. The operation of this mode is illustrated in Figure 3.6. A downstream port’s slot power is
controlled by the Power Controller Control (PCC) bit in the PCI Express Slot Control (PCIESCTL) register
Figure 3.6 Power Enable Controlled Reset Output Mode Operation
While slot power is disabled, the corresponding downstream port reset output is asserted.
When slot power is enabled by writing a zero to the PCC bit, the Port x Power Enable Output (PxPEP) is
asserted and then power to the slot is enabled and the corresponding downstream port reset output is
negated. The time between the assertion of the PxPEP signal and the negation of the PxRSTN signal is
controlled by the value in the Slot Power to Reset Negation (PWR2RST) field in the HPCFGCTL register.
While slot power is enabled, the corresponding downstream port reset output is negated.
When slot power is disabled by writing a one to the PCC bit, the corresponding downstream port reset
output is asserted and then slot power is disabled. The time between the assertion of the PxRSTN signal
and the negation of the PxPEP signal is controlled by the value in the Reset Negation to Slot Power
(RST2PWR) field in the HPCFGCTL register.
Power Good Controlled Reset Output
As in the Power Enable Controlled Reset mode, in this mode a downstream port reset output state is
controlled as a side effect of slot power being turned on or off. However, the timing in this mode depends on
the power good state of the slot’s power supply. The operation of this mode is illustrated in Figure 3.7.
Figure 3.7 Power Good Controlled Reset Output Mode Operation
The operation of this mode is similar to that of the Power Enable Controlled Reset mode except that
when power is enabled, the negation of the corresponding port reset output occurs as a result of and after
assertion of the slot’s Power Good (PxPWRGDN) signal is observed. The time between the assertion of the
PxPWRGDN signal and the negation of the PxRSTN signal is controlled by the value in the Slot Power to
Reset Negation (PWR2RST) field in the HPCFGCTL register.
When slot power is disabled by writing a one to the PCC bit, the corresponding downstream port reset
output is asserted and then slot power is disabled. The time between the assertion of the PxRSTN signal
and the negation of the PxPEP signal is controlled by the value in the Reset Negation to Slot Power
(RST2PWR) field in the HPCFGCTL register.
If at any point while a downstream port is not being reset (i.e., PxRSTN is negated) a power fault is
detected (i.e., PxPWRGDN is negated), then the corresponding port reset output is immediately asserted.
PxPEP
PxRSTN
T
PWR2RST
T
RST2PWR
PxPEP
PxPWRGDN
T
PWR2RST
PxRSTN
T
RST2PWR
Summary of Contents for 89HPES34H16
Page 10: ...IDT Table of Contents PES34H16 User Manual iv October 30 2008 Notes...
Page 12: ...IDT List of Tables PES34H16 User Manual vi October 30 2008 Notes...
Page 18: ...IDT Register List PES34H16 User Manual xii October 30 2008 Notes...
Page 40: ...IDT Upstream Port Failover PES34H16 User Manual 2 6 October 30 2008 Notes...
Page 86: ...IDT Power Management PES34H16 User Manual 7 4 October 30 2008 Notes...
Page 172: ...IDT Configuration Registers PES34H16 User Manual 9 80 October 30 2008 Notes...