11. Signals and Pinout
196
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
11.1.3
PCI-1 Signals
This section describes PowerSpan II signals used to interface to PCI-1. Signals in this group are
compatible with both 3V and 5V signaling environments
—
as defined by the
PCI 2.2 Specification
.
summarizes the signals in this grouping. Signals with electrical characteristics different from
the remainder of the group are placed at the end of the table.
PB_DVSS
Ground
-
-
PB Digital VSS:
Ground pin to
the digital circuits in the PB Phase
Locked Loop.
PB_AVSS
Ground
-
-
PB Analog VSS:
Ground pin to
the digital circuits in the PB Phase
Locked Loop.
a.
Pull-up resistors are not required on the processor bus address (PB_A[0:31]) and data (PB_D[0:63]) signals to guarantee
functional operation of the PowerSpan II. However, adding resistors to the address and data signals minimizes the current
drawn by the PowerSpan II's tristated buffers when the bus is in an idle condition. The system designer must decide whether
to add these resistors to the address and data bus.
b.
A pull-up resistor must be added to the signal if all the external masters in the system support extended cycles. If any external
master in the system does not support extended cycles, PowerSpan II’s TSIZ[0] signal must be disconnected and a pull-down
resistor must be used on the signal. Refer to
B. “Typical Applications” on page 421
for a description and illustration of this type
of system.
Table 56: PCI-1 Signals
a
Pin Name
Pin Type
Description
P1_AD [63:0]
Tristate bidirectional
PCI-1 Address/Data Bus:
Address and data are multiplexed over these pins
providing a 64-bit address/data bus.
b
P1_ACK64#
Tristate bidirectional
PCI-1 Acknowledge 64-bit Transaction:
Active low signal asserted by a target
to indicate its willingness to participate in a 64-bit transaction. Driven by the
target; sampled by the master. Rescinded by the target at the end of the
transaction.
P1_CBE[7:0]# Tristate
bidirectional
PCI-1 Bus Command and Byte Enable Lines:
Command and byte enable
information is multiplexed over all eight CBE lines.
P1_DEVSEL#
Tristate bidirectional
PCI-1 Device Select:
An active low indication from an agent that is the target of
the current transaction. Driven by the target; sampled by the master. Rescinded
by the target at the end of the transaction.
Table 55: Processor Bus Signals
Pin Name
Pin Type
Reset State
Recommended
Termination
Description