Texas Instruments Dual/Single Socket CardBus and UntraMedia Controller PCI7621 - Manual (Page 78)

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3.8.2 Integrated Low-Dropout Voltage Regulator (LDO-VR)
The PCI7x21/PCI7x11 controller requires 1.5-V core voltage. The core power can be supplied by the
PCI7x21/PCI7x11 controller itself using the internal
LDO-VR. The core power can alternatively be supplied by an
external power supply through the VR_PORT terminal. Table 3−14 lists the requirements for both the internal core
power supply and the external core power supply.
Table 3−14. Requirements for Internal/External 1.5-V Core Power Supply
SUPPLY VCC VR_EN VR_PORT NOTE
Internal 3.3 V GND 1.5-V output
Internal 1.5-V LDO-VR is enabled. A 1.0- µ F bypass capacitor is required on the VR_PORT
terminal for decoupling. This output is not for external use.
External 3.3 V VCC 1.5-V input
Internal 1.5-V LDO-VR is disabled. An external 1.5-V power supply, of minimum 50-mA
capacity, is required. A 0.1-
µ F bypass capacitor on the VR_PORT terminal is required.
3.8.3 CardBus (Functions 0 and 1) Clock Run Protocol
The PCI CLKRUN feature is the primary method of power management on the PCI interface of the PCI7x21/PCI7x11
controller. CLKRUN signaling is provided through the MFUNC6 terminal. Since some chip sets do not implement
CLKRUN, this is not always available to the system designer, and alternate power-saving features are provided. For
details on the CLKRUN protocol see the PCI Mobile Design Guide.
The PCI7x21/PCI7x11 controller does not permit the central resource to stop the PCI clock under any of the following
conditions:
• Bit 1 (KEEPCLK) in the system control register (PCI offset 80h, see Section 4.29) is set.
•
The 16-bit PC Card resource manager is busy.
• The PCI7x21/PCI7x11 CardBus master state machine is busy. A cycle may be in progress on CardBus.
•
The PCI7x21/PCI7x11 master is busy. There may be posted data from CardBus to PCI in the
PCI7x21/PCI7x11 controller.
• Interrupts are pending.
•
The CardBus CCLK for the socket has not been stopped by the PCI7x21/PCI7x11 CCLKRUN manager.
•
Bit 0 (KEEP_PCLK) in the miscellaneous configuration register (PCI offset F0h, see Section 7.23) is set.
• The 1394 resource manager is busy.
•
The PCI7x21/PCI7x11 1394 master state machine is busy. A cycle may be in progress on 1394.
•
The PCI7x21/PCI7x11 master is busy. There may be posted data from the 1394 bus to PCI in the
PCI7x21/PCI7x11 controller.
•
PC Card interrogation is in progress.
•
The 1394 bus is not idle.
The PCI7x21/PCI7x11 controller restarts the PCI clock using the CLKRUN protocol under any of the following
conditions:
• A 16-bit PC Card IREQ or a CardBus CINT has been asserted by either card.
•
A CardBus CBWAKE (CSTSCHG) or 16-bit PC Card STSCHG/RI event occurs in the socket.
• A CardBus attempts to start the CCLK using CCLKRUN.
•
A CardBus card arbitrates for the CardBus bus using CREQ.
•
A 1394 device changes the status of the twisted pair lines from idle to active.
• Bit 1 (KEEPCLK) in the system control register (PCI offset 80h, see Section 4.29) is set.
•
Data is in any of the FIFOs (receive or transmit).
•
The master state machine is busy.
• There are pending interrupts.
3.8.4 CardBus PC Card Power Management
The PCI7x21/PCI7x11 controller implements its own card power-management engine that can turn off the CCLK to
a socket when there is no activity to the CardBus PC Card. The PCI clock-run protocol is followed on the CardBus
CCLKRUN interface to control this clock management.