DESIGN FEATURES 48 Volt Hot Swap Controller
for Negative Voltages by Henry Yun
and Robert Reay Introduction
As supply voltages for PC boards continue to drop, designers face the
difficult task of minimizing the voltage drops through distributed power
systems. At operating voltages of 3.3V
or lower, the voltage drops across
power busses, connector pins and
inrush control circuitry can cause a
supply voltage to drop out of tolerance. A solution to this problem is to
distribute power at a high voltage,
commonly 48V, and then step the
voltage down to the final desired value
on each board in the system, using
power modules.
Most 48V power modules require
an input bypass capacitor with a typical value of hundreds of microfarads.
When the board is hot-plugged into a
live 48V power rail, the input capacitor can draw huge inrush currents as
it charges. The inrush current can
cause permanent damage to the
board’s components and create
glitches on the system power supply …