TOP242-250
Key Application Considerations
TOPSwitch-II vs. TOPSwitch-GX
Table 4 compares the features and performance differences
between TOPSwitch-GX and TOPSwitch-II. Many of the new
features eliminate the need for additional discrete components.
Other features increase the robustness of design, allowing cost
savings in the transformer and other power components.
TOPSwitch-GX
Function
Figures
TOPSwitch-II TOPSwitch-GX
Advantages
Soft-Start
N/A*
N/A*
67%
10 ms
• Limits peak current and voltage
component stresses during start-
up
• Eliminates external components
used for soft-start in most
applications
• Reduces or eliminates output
overshoot
External Current
Limit
Programmable 100% 11,20,21, • Smaller transformer
to 30% of default
current limit
24,25,27, • Higher efficiency
28,34,35, • Allows power limiting (constant
38,39
overload power independent of
line voltage)
• Allows use of larger device for
lower losses, higher efficiency
and smaller heatsink
DCMAX
78%
7
• Smaller input cap (wider dynamic
range)
• Higher power capability (when
used with RCD clamp for large
VOR)
• Allows use of Schottky secondary
rectifier diode for up to 15 V
output for high efficiency
Line Feed-Forward
with DC MAX Reduction
N/A*
N/A*
N/A*
78% to 38%
7,11,17, • Rejects line ripple
26,27,28,
31,40
Line OV Shutdown
Line UV Detection
Single resistor
programmable
11,17,19, • Increases voltage withstand
26,27,28
31,33,40
capability against line surge
Single resistor
programmable
11,17,18, • Prevents auto-restart glitches
26,27,28, during power down
31,32,40
Switching Frequency 100 kHz ±10%
132 kHz ±6%
13,15
• Smaller transformer
• Below start of conducted EMI
limits
Table 4. Comparison Between TOPSwitch-II and TOPSwitch-GX (continued on next page). *Not available
M
26 12/04
POWERINT [ Power Integrations ]
