LNK353/354
BYPASS
(BP)
DRAIN
(D)
REGULATOR
5.8 V
FAULT
PRESENT
AUTO-
RESTART
COUNTER
CLOCK
RESET
6.3 V
5.8 V
4.85 V
BYPASS PIN
UNDER-VOLTAGE
+
-
CURRENT LIMIT
COMPARATOR
+
-
VI
LIMIT
JITTER
CLOCK
DC
MAX
OSCILLATOR
FEEDBACK
(FB)
1.65 V -V
T
S
R
Q
Q
LEADING
EDGE
BLANKING
THERMAL
SHUTDOWN
SOURCE
(S)
PI-2367-021105
Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
Power MOSFET drain connection. Provides internal operating
current for both start-up and steady-state operation.
BYPASS (BP) Pin:
Connection point for a 0.1
µF
external bypass capacitor for the
internally generated 5.8 V supply.
FEEDBACK (FB) Pin:
During normal operation, switching of the power MOSFET is
controlled by this pin. MOSFET switching is terminated when
a current greater than 49
µA
is delivered into this pin.
SOURCE (S) Pin:
This pin is the power MOSFET source connection. It is also the
ground reference for the BYPASS and FEEDBACK pins.
P Package (DIP-8B)
G Package (SMD-8B)
S
S
BP
FB
1
2
3
4
8
7
S
S
5
D
PI-3491-111903
Figure 3. Pin Configuration.
2
F
2/05
POWERINT [ POWER INTEGRATIONS, INC. ]
