TOP257YN Datasheet, PDF (25/48 Pages) Power Integrations, Inc. – Enhanced EcoSmart®, Integrated Off-Line Switcher with Advanced Feature Set and Extended Power Range

TOP252-262
Key Application Considerations
TOPSwitch-HX vs. TOPSwitch-GX
Table 4 compares the features and performance differences
between TOPSwitch-HX and TOPSwitch-GX. 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-HX vs. TOPSwitch-GX
Function
TOPSwitch-GX
TOPSwitch-HX
TOPSwitch-HX Advantages
EcoSmart
Linear frequency reduction to
30 kHz (@ 132 kHz) for
duty cycles < 10%
Multi-mode operation with
linear frequency reduction to
30 kHz (@ 132 kHz) and
multi-cycle modulation
(virtually no audible noise)
• Improved efficiency over load (e.g. at 25% load
point)
• Improved standby efficiency
• Improved no-load consumption
Output Overvoltage
Protection (OVP)
Not available
Line Feed-Forward with Duty Linear reduction
Cycle Reduction
Switching Frequency DIP-8 132 kHz
Package
User programmable primary _{• Protects power supply output during open loop fault}
or secondary hysteretic or _{• Maximum design flexibility}
latching OVP
Dual slope reduction with
lower, more accurate onset
point
• Improved line ripple rejection
• Smaller DC bus capacitor
66 kHz
• Increased output power for given MOSFET size due
to higher efficiency
Lowest MOSFET On
3.0 Ω (TOP246P)
Resistance in DIP-8 Package
I²f Trimming
Not available
Auto-restart Duty Cycle
5.6%
Frequency Jitter
±4 kHz @ 132 kHz
±2 kHz @ 66 kHz
1.8 Ω (TOP258P)
-10% / +20%
2%
±5 kHz @ 132 kHz
±2.5 kHz @ 66 kHz
• Increased output power in designs without external
heatsink
• Increased output power for given core size
• Reduced over-load power
• Reduced delivered average output power during
open loop faults
• Reduced EMI filter cost
Thermal Shutdown
External Current Limit
130 °C to 150 °C
30%-100% of I
LIMIT
135 °C to 150 °C
• Increased design margin
30%-100% of I , additional
LIMIT
•
Reduced tolerances when current limit is set
trim at 0.7 × I
LIMIT
externally
Line UV Detection Threshold 50 μA (2 MΩ sense
impedance)
25 μA (4 MΩ sense
impedance)
• Reduced dissipation for lower no-load consumption
Soft-Start
10 ms duty cycle and current 17 ms sweep through multi-
limit ramp
mode characteristic
• Reduced peak current and voltage component
stress at startup
• Smooth output voltage rise
Table 4. Comparison Between TOPSwitch-GX and TOPSwitch-HX.
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Rev. F 01/09