PCI1221 datasheet(40/123 Pages) TI

40 / 123 page

PCI1221 GHK/PDV

PC CARD CONTROLLERS

SCPS042 – JULY 1998

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

suspend mode

The SUSPEND signal provides backward compatibility and gates the PCI reset (PRST) signal from the

PCI1221. However, additional functionality has been defined for SUSPEND to provide additional

power-management options.

SUSPEND provides a mechanism to gate the PCLK from the PCI1221, as well as gate PRST. This can

potentially save power while in an idle state; however, it requires substantial design effort to implement. Some

issues to consider are:

D What if cards are present in the sockets?

D What if the cards in the sockets are powered?

D How to pass CSC (insertion/removal) events.

Even without the PCI clock to the PCI1221 core, asynchronous-type functions (such as RI_OUT) can pass CSC

events, wake-up events, etc., back to the system. If a system designer chooses to not pass card removal events

through to the system, then the PCI1221 would not be able to power down the empty socket without the power

switch clock (CLOCK) generated externally. Refer to the P2C power switch interface for details. Figure 17 is

a functional implementation diagram.

PCI1221

Core

SUSPEND

PRST

GNT

PCLK

Figure 17. SUSPEND Functional Implementation

Figure 18 is a signal diagram of the suspend function.

PCI1221 Datasheet(PDF) 40 Page - Texas Instruments