LNK632DG
DRAIN
(D)
REGULATOR
6 V
BYPASS
(BP/M)
+
-
6 V
5 V
FB
OUT
+
Reset
VILIMIT
D
Q
STATE
MACHINE
FEEDBACK
(FB)
VTH
-
tSAMPLE-OUT
ILIM
DCMAX
Drive
VILIMIT
CABLE DROP
COMPENSATION
FAULT
Auto-Restart
Open-Loop
FB
6.5 V
THERMAL
SHUTDOWN
DCMAX
SAMPLE
tSAMPLE-OUT
DELAY
CONSTANT
CURRENT
CONTROLLER
OSCILLATOR
SOURCE
(S)
+
-
ILIM
SOURCE
(S)
VILIMIT
Current Limit
Comparator
LEADING
EDGE
BLANKING
PI-5293-022309
Figure 2
Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
This pin is the power MOSFET drain connection. It provides
internal operating current for both start-up and steady-state
operation.
D Package (SO-8C)
BYPASS/MULTI-FUNCTIONAL Programmable (BP/M) Pin:
This pin has multiple functions:
1. It is the connection point for an external bypass capacitor for
the internally generated 6 V supply.
1
2
8
7
FB
S
S
BP/M
6
5
S
S
2. It is a mode selection for the cable drop compensation.
4
D
FEEDBACK (FB) Pin:
During normal operation, switching of the power MOSFET is
controlled by this pin. This pin senses the AC voltage on the bias
winding. This control input regulates both the output voltage in
CV mode and output current in CC mode based on the Flyback
voltage of the bias winding. The internal inductance correction
circuit uses the forward voltage on the bias winding to sense the
bulk capacitor voltage.
PI-4907-032808
Figure 3. Pin Configuration.
SOURCE (S) Pin:
This pin is internally connected to the output MOSFET source for
high voltage power and control circuit common returns.
2
Rev. C 09/09
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