PI7C7300DNAE Pericom Semiconductor, PI7C7300DNAE Datasheet - Page 44

• Manufacturer Part Number: PI7C7300DNAE
• Description: IC PCI-PCI BRIDGE 3PORT 272-BGA
• Manufacturer: Pericom Semiconductor

Specifications of PI7C7300DNAE

• Applications: *
• Interface: *
• Voltage - Supply: *
• Package / Case: 272-PBGA
• Mounting Type: Surface Mount
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 3 V to 3.6 V
• Supply Current (max): 660 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

5.2.1
Pericom Semiconductor
transactions are ongoing on the secondary bus, PI7C7300D response to the secondary
bus I/O transactions is not predictable. Configure the I/O base and limit address
registers, ISA enable bit, VGA mode bit, and VGA snoop bit before setting I/O enable
and master enable bits, and change them subsequently only when the primary and
secondary PCI buses are idle.
I/O BASE AND LIMIT ADDRESS REGISTER
PI7C7300D implements one set of I/O base and limit address registers in configuration
space that define an I/O address range per port downstream forwarding. PI7C7300D
supports 32-bit I/O addressing, which allows I/O addresses downstream of PI7C7300D
to be mapped anywhere in a 4GB I/O address space.
I/O transactions with addresses that fall inside the range defined by the I/O base and limit
registers are forwarded downstream from the primary PCI bus to the secondary PCI bus.
I/O transactions with addresses that fall outside this range are forwarded upstream from
the secondary PCI bus to the primary PCI bus.
The I/O range can be turned off by setting the I/O base address to a value greater than
that of the I/O limit address. When the I/O range is turned off, all I/O trans-actions are
forwarded upstream, and no I/O transactions are forwarded downstream. The I/O range
has a minimum granularity of 4KB and is aligned on a 4KB boundary. The maximum I/O
range is 4GB in size. The I/O base register consists of an 8-bit field at configuration
address 1Ch, and a 16-bit field at address 30h. The top 4 bits of the 8-bit field define bits
[15:12] of the I/O base address.
The bottom 4 bits read only as 1h to indicate that PI7C7300D supports 32-bit I/O
addressing. Bits [11:0] of the base address are assumed to be 0, which naturally aligns
the base address to a 4KB boundary. The 16 bits contained in the I/O base upper 16 bits
register at configuration offset 30h define AD[31:16] of the I/O base address. All 16 bits
are read/write. After primary bus reset or chip reset, the value of the I/O base address is
initialized to 0000 0000h.
The I/O limit register consists of an 8-bit field at configuration offset 1Dh and a 16-bit
field at offset 32h. The top 4 bits of the 8-bit field define bits [15:12] of the I/O limit
address. The bottom 4 bits read only as 1h to indicate that 32-bit I/O addressing is
supported. Bits [11:0] of the limit address are assumed to be FFFh, which naturally aligns
the limit address to the top of a 4KB I/O address block. The 16 bits contained in the I/O
limit upper 16 bits register at configuration offset 32h define AD[31:16] of the I/O limit
address. All 16 bits are read/write. After primary bus reset or chip reset, the value of the
I/O limit address is reset to 0000 0FFFh.
Note: The initial states of the I/O base and I/O limit address registers define an I/O range
of 0000 0000h to 0000 0FFFh, which is the bottom 4KB of I/O space. Write these
registers with their appropriate values before setting either the I/O enable bit or the
master enable bit in the command register in configuration space.
Page 44 of 107
3-PORT PCI-TO-PCI BRIDGE
November 2005 - Revision 1.01
PI7C7300D