The LT4220 16-pin dual voltage Hot Swap controller allows a board to be safely inserted and removed from a live backplane. The device operates with any combination of 2.7V to 16.5V and -2.7V to -16.5V supplies. Using two external N-channel pass transistors, the board supply voltages can be ramped up at an adjustable rate. A selectable tracking mode allows dual supply tracking control for ramping the positive and negative supplies together. The LT4220 features foldback current limit and latches off both gates if either supply remains in current limit longer than an adjustable time amount. The IC can be configured for automatic restart after a delay set by the same timer. A power good signal indicates when the output voltages monitored by the two FB comparators are within tolerance, and the gate drive signals are at their full on voltage. The LT4220 is available in a 16-lead narrow SSOP package.
