LNK562-564
BYPASS
(BP)
DRAIN
(D)
REGULATOR
5.8 V
AUTO-RESTART
COUNTER
BYPASS PIN
UNDER-VOLTAGE
FAULT
PRESENT
0.8 V
+
-
RESET
+
5.8 V
4.85 V
CURRENT LIMIT
COMPARATOR
6.3 V
+
-
V
ILIMIT
JITTER
CLOCK
DCMAX
ADJ
THERMAL
SHUTDOWN
OSCILLATOR
FEEDBACK
(FB)
1.69 V -VTH
S
R
Q
Q
OPEN LOOP
PULLDOWN
LEADING
EDGE
BLANKING
PI-3958-092905
SOURCE
(S)
Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
The power MOSFET drain connection provides internal
operating current for both startup and steady-state operation.
P Package (DIP-8B)
G Package (SMD-8B)
D Package (SO-8C)
BYPASS (BP) Pin:
A0.1 μF external bypass capacitor for the internally generated
5.8 V supply is connected to this pin.
S
S
BP
S
S
S
S
1
2
8
7
1
2
8
7
FB
BP
FB
3
4
6
5
S
S
FEEDBACK (FB) Pin:
D
5
4
D
During normal operation, switching of the power MOSFET is
controlled by this pin. MOSFET switching is disabled when a
current greater than 70 μA flows into this pin.
PI-4547-011107
SOURCE (S) Pin:
This pin is the power MOSFET source connection. It is also the
ground reference for the BYPASS and FEEDBACK pins.
Figure 3. Pin Configuration.
protection, frequencyjittering, currentlimitcircuit, andleading
edge blanking.
LinkSwitch-LP Functional
Description
LinkSwitch-LPcomprisesa700VpowerMOSFETswitchwith
a power supply controller on the same die. Unlike conventional
PWM (pulse width modulation) controllers, it uses a simple
ON/OFF control to regulate the output voltage. The controller
consists of an oscillator, feedback (sense and logic) circuit, 5.8
Vregulator,BYPASSpinundervoltagecircuit,over-temperature
Oscillator
The typical oscillator frequency is internally set to an average
of 66/83/100 kHz for the LNK562, 563 & 564 respectively.
Two signals are generated from the oscillator: the maximum
duty cycle signal (DCMAX) and the clock signal that indicates
the beginning of each switching cycle.
2
Rev. H 11/08
POWERINT [ Power Integrations ]
