RDK-242 Power Integrations, RDK-242 Datasheet - Page 12

• Manufacturer Part Number: RDK-242
• Description: Power Management Modules & Development Tools TOPSwitch-JX REF. DESIGN KIT
• Manufacturer: Power Integrations
• Type: MOSFET & Power Driverr

Specifications of RDK-242

• Input Voltage: 85 VAC to 264 VAC
• Output Voltage: 12 V
• Maximum Operating Temperature: + 40 C
• Minimum Operating Temperature: 0 C
• Operating Supply Voltage: 85 VAC to 264 VAC
• Product: Power Management Modules

additional current to V pin from the bias supply and together with R1 and R2 sets the
threshold current for V pin with reduced power loss and thus helps further improvement
on the no-load input power.
4.2.6 Output Feedback
Schottky diodes D8 and D9 rectify the output. A snubber network (C12, R17) dampens
ringing across the diodes and reduces high frequency conducted and radiated noise.
Capacitors C14 and C15 provide output filtering. Resistors R21 and R23 provide a
voltage divider and set the DC set point of the output. C20, R21, and R19 provide
compensation for the feedback control loop and C18 and R18 is a phase boost network
to improve the phase margin of the unit. Resistor R19 limits the gain of the feedback
system to ensure power supply stability throughout the range of operation. Diode D10
provides a fast discharge path for C20 when the output turns-off and to allow smooth rise
of the output voltage when the unit is turned on again.
4.2.7 Output Inductor Post Filter Soft-Finish
To prevent output overshoot during start-up the voltage that appears across L2 was used
to provide a soft-finish function. When the voltage across L2 exceeds the forward drop of
U2A and D10 current flows though the optocoupler LED and provides feedback to the
primary. This arrangement acts to limit the rate of rise of the output voltage until it
reaches regulation and eliminates the capacitor that is typically placed across U3 to
provide the same function.
Power Integrations, Inc.
Tel: [phone] Fax: [phone]
www.powerint.com
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