Datasheet

3−21
RESET
GNT
SUSPEND
PCLK
RESETIN
SUSPENDIN
PCLKIN
External Terminals
Internal Signals
Figure 3−15. Signal Diagram of Suspend Function
3.8.6 Requirements for Suspend Mode
The suspend mode prevents the clearing of all register contents on the assertion of reset (PRST or GRST) which
would require the reconfiguration of the PCI1520 by software. Asserting the SUSPEND
signal places the PCI outputs
of the controller in a high-impedance state and gates the PCLK signal internally to the controller unless a PCI
transaction is currently in process (GNT
is asserted). It is important that the PCI bus not be parked on the PCI1520
when SUSPEND
is asserted because the outputs are in a high-impedance state.
The GPIOs, MFUNC signals, and RI_OUT
signal are all active during SUSPEND, unless they are disabled in the
appropriate PCI1520 registers.
3.8.7 Ring Indicate
The RI_OUT output is an important feature in power management, allowing a system to go into a suspended mode
and wake up on modem rings and other card events. TI-designed flexibility permits this signal to fit wide platform
requirements. RI_OUT
on the PCI1520 can be asserted under any of the following conditions:
• A 16-bit PC Card modem in a powered socket asserts RI
to indicate to the system the presence of an
incoming call.
• A powered down CardBus card asserts CSTSCHG (CBWAKE) requesting system and interface wake up.
• A powered CardBus card asserts CSTSCHG from the insertion/removal of cards or change in battery
voltage levels.
Figure 3−16 shows various enable bits for the PCI1520 RI_OUT
function; however, it does not show the masking of
CSC events. See Table 3−9 for a detailed description of CSC interrupt masks and flags.