TOP242-250 POWERINT [Power Integrations, Inc.], TOP242-250 Datasheet - Page 32

• Manufacturer Part Number: TOP242-250
• Description: TOPSwitch-GX Family Extended Power, Design Flexible, EcoSmart, Integrated Off-line Switcher
• Manufacturer: POWERINT [Power Integrations, Inc.]

Figure 49. Layout Considerations for TOPSwitch-GX using R Package.
Quick Design Checklist
As with any power supply design, all TOPSwitch-GX designs
should be verified on the bench to make sure that components
specifications are not exceeded under worst case conditions. The
following minimum set of tests is strongly recommended:
1. Maximum drain voltage – Verify that peak V
2. Maximum drain current – At maximum ambient temperature,
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exceed 675 V at highest input voltage and maximum
overload output power. Maximum overload output power
occurs when the output is overloaded to a level just before the
power supply goes into auto-restart (loss of regulation).
maximum input voltage and maximum output load, verify
drain current waveforms at start-up for any signs of
transformer saturation and excessive leading edge current
spikes. TOPSwitch-GX has a leading edge blanking time of
220 ns to prevent premature termination of the ON-cycle.
Verify that the leading edge current spike is below the
allowed current limit envelope (see Figure 52) for the
drain current waveform at the end of the 220 ns blanking
period.
TOP242-250
M
12/04
Solder Side
Component Side
HV
+
-
R1a - 1c
TOPSwitch-GX
X
D
L
C
Input Filter
DS
S
Capacitor
does not
3. Thermal check – At maximum output power, minimum
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 website: www.powerint.com
BIAS
PRI
PRI
input voltage and maximum ambient temperature, verify
that temperature specifications are not exceeded for
TOPSwitch-GX, transformer, output diodes and output
capacitors. Enough thermal margin should be allowed for
the part-to-part variation of the R
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
under test and the worst case maximum specification.
Safety Spacing
Capacitor
coupler
Opto-
Y1-
m
T
a
n
s
o
e
r
f
r
r
SEC
Maximize hatched copper
areas (
heat sinking
DS(ON)
Output Filter Capacitors
) for optimum
DS(ON)
of TOPSwitch-GX,
of the device
-
PI-2734-043001
Out
DC
+