TOP249Y Extended Power, Design Flexible Pin Functional Description
DRAIN (D) Pin:
High voltage power MOSFET drain output.  The internal start-
up bias current is drawn from this pin through a switched high-
voltage current source.  Internal current limit sense point for
drain current.
CONTROL (C) Pin:
Error amplifier and feedback current input pin for duty cycle
control.  Internal shunt regulator connection to provide internal
bias current during normal operation.  It is also used as the
connection point for the supply bypass and auto-restart/
compensation capacitor.
LINE-SENSE (L) Pin:  (Y or R package only)
Input pin for OV, UV, line feed forward with DCMAX reduction,
remote ON/OFF and synchronization.  A connection to SOURCE
pin disables all functions on this pin.
EXTERNAL CURRENT LIMIT (X) Pin: (Y or R package only)
Input pin for external current limit adjustment, remote
ON/OFF, and synchronization. A connection to SOURCE pin
disables all functions on this pin.