Design Solutions 12
May 2003
Design Guidelines for CompactPCI Hot Swap Control
Applications Using the LTC1644
by Andy Gardner
Introduction Long and Medium Power Pin Connections The LTCВ®1644 is designed for CompactPCITM Hot SwapTM
control applications requiring –12V, 5V, 3.3V and 12V
supplies (see Figure 1). The LTC1644 also precharges the
bus I/O pins during hot insertion and extraction, feeds
back the status of the back-end supply voltages with its
PWRGD output, and intercepts the PCI_RST# signal onchip using the RESETIN and RESETOUT pins. There are
several important considerations in circuit design and
component selection for CompactPCI Hot Swap control
applications using the LTC1644. CompactPCI connectors have both long and medium
length GND, 5V, 3.3V and VI/O power pins as well as
medium length –12V and 12V power pins. In general,
medium length power pins are used for “Back End Power
Planes” where the connector pins are isolated from the
load by the LTC1644. The long connector pins may be
used to provide “Early Power” to loads that require power
immediately upon hot insertion without the benefit of BACKPLANE
CONNECTOR C8
0.01ВµF …