LNK623-626
DRAIN
(D)
REGULATOR
6 V
BYPASS
(BP)
+
-
6 V
5 V
FB
OUT
+
-
Reset
VILIMIT
D
Q
STATE
MACHINE
FEEDBACK
(FB)
VTH
tSAMPLE-OUT
ILIM
DCMAX
Drive
FAULT
FB
Auto-Restart
Open-Loop
6.5 V
THERMAL
SHUTDOWN
DCMAX
SAMPLE
DELAY
tSAMPLE-OUT
OSCILLATOR
SOURCE
(S)
+
ILIM
SOURCE
(S)
VILIMIT
-
Current Limit
Comparator
LEADING
EDGE
BLANKING
PI-5197-110408
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.
P Package (DIP-8C)
D Package (SO-8C)
FB
S
S
1
2
8
7
1
2
8
7
FB
BP
S
S
S
S
BYPASS (BP) Pin:
This pin is the connection point for an external bypass capacitor
for the internally generated 6 V supply.
BP
6
5
6
5
S
S
4
D
FEEDBACK (FB) Pin:
D
4
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 the output voltage
based on the flyback voltage of the bias winding.
3a
3b
PI-5198-071608
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. E 09/09
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