Texas Instruments PCI1520 manual PC Card Interface

SCPA033

5 PC Card Interface

There are two different modes on the PC Card interface. The first is 16-bit mode which is analogous to the legacy ISA bus. The second is 32-bit CardBus mode which is very similar to a PCI Bus. The terminal functions for these two modes are multiplexed and routed to the PC Card sockets. The following suggestions apply to the PC Card interface:

•Pullup resistors for the PC Card interface have been integrated into the PCI1520. These include: A14/CPERR#, A15/CIRDY#, A19/CBLOCK#, A20/CSTOP#, A21/CDEVSEL#, A22/CTRDY#, BVD2(SPKR#)/CAUDIO, CD1#/CCD1#, CD2#/CCD2#, INPACK#/CREQ#, READY/CINT#, RESET/CRST#, VS1#/CVS1, VS2#/CVS2, WAIT#/CSERR#, WP(IOIS16#)/CCLKRUN#.

•A switchable pullup/pulldown resistor has been implemented on BVD1(STSCHG#)/CSTSCHG. The pulldown is implemented when a CardBus card is being used or when the socket is empty. A pullup is implemented when a 16-bit PC card is being used.

•A damping resistor is necessary on the CCLK terminals between the PCI1520 and the PC Card sockets. The value is system dependent. If line impedance is in the

range of 60-90Ω , a 47Ω resistor is recommended. For more information, please see the PC Card Standard Revision 7.1, Section 5.3.2.1.4.

•CD# line noise filtering is no longer required because the PCI1520 has an integrated digital noise filter.

•Three PC Card terminals on each socket are not necessary for CardBus mode but are necessary for 16-bit mode. These terminals are: CRSVD/D14, CRSVD/A18, and CRSVD/D2. These terminals must be connected to the PC Card Socket according to their 16-bit designations. By default, when in CardBus mode, these terminals are driven low. They can be tristated by setting bit 22 (CBRSVD) in the System Control register at PCI configuration offset 80h.

•Texas Instruments provides single socket CardBus controllers such as the PCI1510 for systems requiring only one PC card socket. However, the PCI1520 can be used as a single socket controller simply by leaving the Socket B interface floating.

PCI1520 Implementation Guide 7