Hardware compatibility issues in the PC card power interface

The PC Card market has moved far beyond its original target of a memory card standard interface. Today there is a constant flow of new applications for PC Card slots. This trend started with fax/modems and went on to GPS, Ethernet, SCSI, pagers, hard disk drives, data acquisition devices, multi-function cards, and wireless applications. As their sophistication increases, so do the power requirements of the new PC Cards. For portable products running on batteries, power management and allocation is of major importance. The original PCMCIA standard did not set boundaries on either the power allotted to the slot or the load characteristics of the cards. The result is a potential compatibility hazard because of the mismatch between the power handling capability of a slot in a battery powered platform and the power requirement of some higher-function cards. This paper will describe the boundaries or safe operating area for the power-up sequence of PC Cards