Texas Instruments PCI445X manual Prst PCI reset and Grst Global reset, INTA, INTB, and Intc

System Implementation

IDSEL, there is no alternative. If another AD line is to be used for IDSEL, then the system designer must leave the pullup off LATCH and use MFUNC7 to route IDSEL. Also, if AD23 is used, then the resistive coupling should not be used.

Refer to the Implementation Note: System Generation of IDSEL in the PCI Local Bus Specification, Revision 2.2 (section 3.2.2.3.5). PCI Local Bus Specification, Revision 2.2 (section 4.2.6, footnote 31) recommends resistive coupling. A 100-Ωresistor is recommended.

￿PRST (PCI reset) and G_RST (Global reset)

G_RST initializes all of the registers and state-machines of the PCI445X device, and PRST does not. G_RST should be asserted during power-on and rebooting. It puts the PCI445X device into the initialized state. PRST does not initialize global-reset-only bits and, if PME is enabled, PME context bits. Refer to Table A±1, Global Reset Only Cleared Bits, and Table A±2, PME Context Bits. PRST is connected to PCI RESET; G_RST requires a special signal in the motherboard. It will come from the chipset.

If the system does not support wake-up from D3cold, then PRST and G_RST can be tied together. Note that G_RST and PRST are clamped to VCCP.

￿INTA, INTB, and INTC

When using one of the parallel PCI interrupt modes, INTA, INTB, and INTC should be connected to the PCI interrupt lines. If the INTRTIE bit (system control register, PCI offset 80h, bit 29) is set, then both CardBus functions (functions 0 and 1) will signal and report INTA, and only INTA and INTC will need to be routed. If the TIEALL bit (system control register, PCI offset 80h, bit 28) is set, then all functions (0, 1, and 2) will report INTA and INTA will be the only interrupt required.

￿CLKRUN

This signal is optional. However, if saving power is a concern, this signal should be implemented. Refer to the PCI Mobile Design Guide Revision 1.1 (Section 2).

￿PME

This signal is required for the ACPI systems. In a notebook PC, this signal is usually connected to the south bridge (ex., PIIX4) or embedded controller (EC). The PME terminal uses an open-drain type buffer.

Note: Pullup Resistor Requirements

A pullup resistor is required for each of the following terminals: IRDY, TRDY, FRAME, STOP, DEVSEL, PERR, SERR, LOCK, PRST, G_RST, INTA, INTB, INTC, CLKRUN, and PME.

PCI445X Device 1-9