LNK362-364 FERYSTER [FERYSTER Inductive Components Manufacturer], LNK362-364 Datasheet - Page 6

• Manufacturer Part Number: LNK362-364
• Description: Energy Effi cient, Low Power Off-Line Switcher IC
• Manufacturer: FERYSTER [FERYSTER Inductive Components Manufacturer]

Figure 6. Recommended Printed Circuit Layout for LinkSwitch-XT using P Package in a Flyback Converter Confi guration.
Bypass Capacitor C
The BYPASS pin capacitor should be located as near as possible
to the BYPASS and SOURCE pins.
Primary Loop Area
The area of the primary loop that connects the input fi lter
capacitor, transformer primary and LinkSwitch-XT together
should be kept as small as possible.
Primary Clamp Circuit
A clamp is used to limit peak voltage on the DRAIN pin at
turn-off. This can be achieved by using an RCD clamp or a
Zener (~200 V) and diode clamp across the primary winding.
In all cases, to minimize EMI, care should be taken to minimize
the circuit path from the clamp components to the transformer
and LinkSwitch-XT.
Thermal Considerations
The copper area underneath the LinkSwitch-XT acts not only
as a single point ground, but also as a heatsink. As this area is
connected to the quiet source node, it should be maximized for
Rev. D 02/07
2-6
6
6
OUT
DC
+
-
TOP VIEW
LNK362-364
BP
m
T
a
n
s
o
e
r
r
r
f
Capacitor
Y1-
Output Filter
Capacitor
D
S
S
coupler
Opto-
good heat sinking of LinkSwitch-XT. The same applies to the
cathode of the output diode.
Y-Capacitor
The placement of the Y-type cap should be directly from the
primary input fi lter capacitor positive terminal to the common/
return terminal of the transformer secondary. Such a placement
will route high magnitude common-mode surge currents away
from the LinkSwitch-XT device. Note that if an input pi (C, L, C)
EMI fi lter is used, then the inductor in the fi lter should be placed
between the negative terminals of the input fi lter capacitors.
Optocoupler
Place the optocoupler physically close to the LinkSwitch-XT to
minimize the primary-side trace lengths. Keep the high current,
high-voltage drain and clamp traces away from the optocoupler
to prevent noise pick up.
Output Diode
For best performance, the area of the loop connecting the
secondary winding, the output diode and the output fi lter
S
S
S
Maximize hatched copper
areas (
heatsinking
BP
S
FB
C
BP
) for optimum
-
HV DC
INPUT
+
PI-4155-102705
Input Filter
Capacitor