IDT PowerSpan II, Руководство пользователя

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9. Resets, Clocks and Power-up Options 173
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
• PWRUP_PRI_PCI
— PCI-1 is always the Primary Interface
9.3.1 Multiplexed System Pin Mode
PowerSpan II multiplexes a number of pins to provide either power-up options or other system
application purposes (see
Table 45 ). The multiplexed system pins mode is the default mode for
PowerSpan II power-up options.
9.3.1.1 Signal Timing Requirements
PWRUP_PB_ARB_EN, PWRUP_P1_ARB_EN, and PWRUP_P2_ARB_EN have multiple purposes:
determines the PLL frequency range, and the PowerSpan II power-up option.
During the low to high transition of PO_RST_, the following pins are latched by PowerSpan II in order
to choose the following internal clock PLL frequency range:
• PB_FAST Signal
— High when the PB clock frequency is between 50 MHz and 100 MHz
— Low when the PB clock frequency is between 25 MHz and 50 MHz
• P1_M66EN Signal
— High when the PCI-1 clock frequency is 66 MHz
— Low when the PCI-1 clock frequency is 33 MHz
• P2_M66EN signal
— High when the PCI-2 clock frequency is 66 MHz
— Low when the PCI-2 clock frequency is 33 MHz
There is a 10 ns minimum input setup time and 10 ns maximum input hold time requirement for
latching these frequency range pins for determining the PLL range (see
Table 97 on page 396 and
Table 102 on page 402 , parameters t
110
and t
111
for more AC Timing reset information).
The arbiter enable and disable (PWR_PB_ARB_EN and PWRUP_P1_ARB_EN) power- up options
are sampled continuously 10 ns the negation of PO_RST_ until the power-up option is updated by the
Configuration Slave mode settings (this is only true in MPC8260 applications). The option is
determined by the logic level of PB_FAST, P1_66EN, and P2_66EN signals through internal
combination logic. This means the system can enable/disable arbiter(s) by controlling these frequency
range pins’ logic level during normal system operation after the negation of PO_RST_ if the
PB_RSTCONF signal is tied to 1 (it never goes low).