Datasheet

TOP242-250
33
I
4/03
capacitors. Enough thermal margin should be allowed for
the part-to-part variation of the R
DS(ON)
of TOPSwitch-GX
as specified in the data sheet. The margin required can
either be calculated from the tolerances or it can be
accounted for by connecting an external resistance in
series with the DRAIN pin and attached to the same
heatsink, having a resistance value that is equal to the
difference between the measured R
DS(ON)
of the device
under test and the worst case maximum specification.
Figure 49. Layout Considerations for TOPSwitch-GX using R Package.
-
HV
+-
DC
Out
PI-2734-043001
T
r
a
n
s
f
o
r
m
e
r
Safety Spacing
Y1-
Capacitor
Solder Side
Component Side
Opto-
coupler
+
Output Filter Capacitors
Maximize hatched copper
areas( ) for optimum
heat sinking
TOP VIEW
Input Filter
Capacitor
R1a - 1c
PRI
PRI
SEC
BIAS
TOPSwitch-GX
S
L
C
X
D
Design Tools
For a discussion on utilizing TOPSwitch-GX in a forward
converter configuration, please refer to the TOPSwitch-GX
Forward Design Methodology Application Note.
Up-to-date information on design tools can be found at the
Power Integrations Web site: www.powerint.com