top250p Power Integrations, Inc., top250p Datasheet - Page 28
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top250p
Manufacturer Part Number
top250p
Description
Extended Power, Design Flexible, Ecosmart, Integrated Off-line Switcher A
Manufacturer
Power Integrations, Inc.
Datasheet
1.TOP250P.pdf
(52 pages)
TOPSwitch-FX vs. TOPSwitch-GX
Table 5 compares the features and performance differences
between TOPSwitch-GX and TOPSwitch-FX. 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 Design Considerations
Power Table
Data sheet power table (Table 1) represents the maximum
practical continuous output power based on the following
conditions: TOP242 to TOP246: 12 V output, Schottky output
diode, 150 V reflected voltage (V
from curves contained in application note AN-29. TOP247
Table 5. Comparison Between TOPSwitch-FX and TOPSwitch-GX. *Not available
Function
Light Load Operation Cycle skipping
Line Sensing/Exter-
nally Set Current
Limit (Y, R and F
Packages)
Current Limit
Programming Range
P/G Package Current
Limits
Y/R/F Package
Current Limits
Thermal Shutdown
Maximum Duty Cycle
Reduction Threshold
Line Under-Voltage
Negative (turn-off)
Threshold
Soft-Start
28
TOP242-250
O
11/05
Line sensing and
externally set current
limit mutually
exclusive (M pin)
100% to 40%
Identical to Y
package
100% (R and F
package N/A*)
125 °C min.
70 °C hysteresis
90 µA
N/A*
10 ms (duty cycle)
TOPSwitch-FX TOPSwitch-GX
OR
) and efficiency estimates
Frequency and duty
cycle reduction
Line sensing and
externally set current
limit possible simul-
taneously (functions
split onto L and X pins
100% to 30%
TOP243-246 P and
G packages internal
current limits reduced
90% (for equivalent
R
130 °C min.
75 °C hysteresis
60 µA
40% of positive
(turn-on) threshold
10 ms (duty cycle +
current limit)
DS(ON)
)
to TOP250: Higher output voltages, with a maximum output
current of 6 A.
For all devices, a 100 VDC minimum for 85-265 VAC and
250 VDC minimum for 230 VAC are assumed and sufficient
heat sinking to keep device temperature ≤100 °C. Power
levels shown in the power table for the R package device
assume 6.45 cm
enclosed adapter, or 19.4 cm
TOPSwitch-GX Selection
Selecting the optimum TOPSwitch-GX depends upon required
maximum output power, efficiency, heat sinking constraints
and cost goals. With the option to externally reduce current
limit, a larger TOPSwitch-GX may be used for lower power
applications where higher efficiency is needed or minimal heat
sinking is available.
• Improves light load efficiency
• Reduces no-load consumption
• Additional design flexibility allows all
• Minimizes transformer core size in highly
• Matches device current limit to package
• Allows more continuous design to lower
• Minimizes transformer core size
• Optimizes efficiency for most applications
• Allows higher output powers in high
• Reduces output line frequency ripple at
• DC
• Provides a well defined turn-off threshold
• Gradually increasing current limit in
• Further reduces component stresses
features to be used simultaneously
continuous designs
dissipation capability
device dissipation (lower RMS currents)
ambient temperature applications
low line
designs using TOP248, TOP249 and
TOP250
as the line voltage falls
addition to duty cycle during soft-start
further reduces peak current and voltage
during start up
2
MAX
of 610 g/m
reduction optimized for forward
TOPSwitch-GX
Advantages
2
in an open frame.
2
copper heat sink area in an