PCI Express Power and Mini Card Solutions – Design Note 346
Mitchell Lee and Vladimir Ostrerov
Introduction
PCI Express is the third generation of PCI (Peripheral
Component Interconnect) technology used to connect
I/O perhipheral devices in computer systems. It is
intended as a general purpose I/O device interconnect
that meets the needs of a wide variety of computing
platforms such as desktop, mobile, server and communications. It also specifies the electrical and mechanical
attributes of the backplane, connectors and removable
cards in these systems. PCI Express Mini Card also provides two power sources:
3.3V and 1.5V. The auxiliary voltage (3.3VAUX) is sourced
over the same pins as the primary 3.3V supply and is
available during the standby/suspend state to support
wake-event processing on the Mini Card. Table 2 summarizes PCI Express Mini Card power specifications. Power Requirements
Each add-in card connector requires two power rails:
12V and 3.3V, along with a third, optional 3.3V auxiliary rail. If the designer elects to provide the auxiliary
3.3V rail in his system or if the platform supports the
WAKE# signal, the 3.3VAUX rail must be supplied to all
connectors. Table 2. Summary of PCI Express Mini Card Supply
Requirements In PCI Express, as in PCI, the Hot Swapв„ў controller is
resident on the platform side of the system, delivering
power to the connectors only after a card is inserted. …