Hot Swap Controller, MOSFET and Sense Resistor Are Integrated in
a 5mm Г— 3mm DFN for Accurate Current Limit and Load Current
Monitoring in Tight Spaces – Design Note 466
Vladimir Ostrerov
Introduction
In general, a Hot Swapв„ў controller provides two important
functions to boards that can be plugged and unplugged
from a live backplane: It limits the potentially destructive inrush current
when a board is plugged in. It acts as a circuit breaker, with the maximum
current and maximum time at that current factored
into the breaker function.
Two of the components required to implement these
functions, the power MOSFET and sense resistor, tend
to dominate the board real estate taken by the Hot Swap
circuit. The LTCВ®4217 saves space by combining these two
components with a Hot Swap controller in a 16-pin 5mm Г—
3mm DFN package (or 20-lead TSSOP). This 2A integrated Hot Swap controller п¬Ѓts easily onto boards operating in
the voltage range from 2.9V to 26.5V. A dedicated 12V
version, LTC4217-12, is also available, which contains
preset 12V specific thresholds. Figure 1 shows how little
space is required for a complete Hot Swap circuit.
LTC4217 Features
Figure 2 shows a simpliп¬Ѓed block diagram of the LTC4217. …