48

PC755/745

2138D–HIREL–06/03

In addition, CKSTP_OUT is an open-drain style output that requires a pull-up resistor (1

k

Ω – 5 kΩ) if it is used by the system.

During inactive periods on the bus, the address and transfer attributes may not be

driven by any master and may, therefore, float in the high-impedance state for relatively

long periods of time. Since the processor must continually monitor these signals for

snooping, this float condition may cause additional power draw by the input receivers on

the processor or by other receivers in the system. These signals can be pulled up

through weak (10 k

Ω) pull-up resistors by the system or may be otherwise driven by the

system during inactive periods of the bus to avoid this additional power draw, but

address bus pull-up resistors are not neccessary for proper device operation. The

snooped address and transfer attribute inputs are:

A[0:31], AP[0:3], TT[0:4], TBST, and GBL.

The data bus input receivers are normally turned off when no read operation is in

progress and, therefore, do not require pull-up resistors on the bus. Other data bus

receivers in the system, however, may require pull-ups, or that those signals be other-

wise driven by the system during inactive periods by the system. The data bus signals

are: DH[0:31], DL[0:31], and DP[0:7].

If 32-bit data bus mode is selected, the input receivers of the unused data and parity bits

will be disabled, and their outputs will drive logic zeros when they would otherwise nor-

mally be driven. For this mode, these pins do not require pull-up resistors, and should be

left unconnected by the system to minimize possible output switching.

If address or data parity is not used by the system, and the respective parity checking is

disabled through HID0, the input receivers for those pins are disabled, and those pins

do not require pull-up resistors and should be left unconnected by the system. If all par-

ity generation is disabled through HID0, then all parity checking should also be disabled

through HID0, and all parity pins may be left unconnected by the system.

Definitions

Datasheet Status

Validity

Objective specification

This datasheet contains target and goal specification for

discussion with customer and application validation.

Before design phase.

Target specification

This datasheet contains target or goal specification for

product development.

Valid during the design phase.

Preliminary specification

∝ site

This datasheet contains preliminary data. Additional data

may be published later; could include simulation result.

Valid before characterization phase.

Preliminary specification

β site

This datasheet contains also characterization results.

Valid before the industrialization

phase.

Product specification

This datasheet contains final product specification.

Valid for production purpose.

Limiting Values

Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or more of the

limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or at

any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values

for extended periods may affect device reliability.

Application Information

Where application information is given, it is advisory and does not form part of the specification.