Table of Contents
Advertisement
Quick Links
Is Now Part of
To learn more about ON Semiconductor, please visit our website at
www.onsemi.com
ON Semiconductor and the ON Semiconductor logo are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries. ON Semiconductor owns the rights to a number
of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of ON Semiconductor's product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. ON Semiconductor reserves the right
to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does ON Semiconductor assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. Buyer is responsible for its products and applications using ON
Semiconductor products, including compliance with all laws, regulations and safety requirements or standards, regardless of any support or applications information provided by ON Semiconductor. "Typical" parameters which may be provided in ON
Semiconductor data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's
technical experts. ON Semiconductor does not convey any license under its patent rights nor the rights of others. ON Semiconductor products are not designed, intended, or authorized for use as a critical component in life support systems or any FDA
Class 3 medical devices or medical devices with a same or similar classification in a foreign jurisdiction or any devices intended for implantation in the human body. Should Buyer purchase or use ON Semiconductor products for any such unintended
or unauthorized application, Buyer shall indemnify and hold ON Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out
of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that ON Semiconductor was negligent regarding the design or manufacture of the part. ON Semiconductor
is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
Advertisement
Table of Contents
Related Manuals for ON Semiconductor Fairchild FAN302HL
Summary of Contents for ON Semiconductor Fairchild FAN302HL
- Page 1 ON Semiconductor does not convey any license under its patent rights nor the rights of others. ON Semiconductor products are not designed, intended, or authorized for use as a critical component in life support systems or any FDA...
- Page 2 www.fairchildsemi.com AN-6094 Design Guideline for Flyback Charger Using FAN302HL/UL 1. Introduction More than half of the external power supplies produced current sensing loss and eliminates all external current- are used for portable electronics such as laptops, cellular control circuitry, facilitating a higher efficiency power phones, and MP3 players that require constant output supply design without incurring additional costs.
-
Page 3: Operation Principle
AN-6094 2. Operation Principle 2-1 Constant-Voltage Regulation Operation Figure 2 shows the internal PWM control circuit of FAN302. The constant voltage (CV) regulation is implemented in the same way as the conventional isolated power supply, where the output voltage is sensed using voltage divider and compared with the internal 2.5 V reference of the shut regulator (KA431) to generate a compensation... -
Page 4: Design Consideration
AN-6094 3. Design Consideration Figure 5. Operation Range of Charger with CC/CV A battery charger power supply with CC output requires a frequency-reduction function to prevent CCM operation more design consideration than the conventional power by extending the switching period as the output voltage supply with a fixed output voltage. -
Page 5: Design Procedure
AN-6094 4. Design Procedure In this section, a design procedure is presented using the Estimated primary-side efficiency FF.P Figure 1 as a reference. An offline charger with 6 W / 5 V secondary-side efficiency (E ) for operating point A, FF.S output has been selected as a design example. - Page 6 AN-6094 The input power of transformer at operating point A is Then, the power supply input power and transformer input given as: power at operating point C are given as: ⋅ (13) IN T FF S ⋅ To reduce the switching frequency as the output voltage (14) IN T drops in CC Mode for maintaining DCM operation, the...
- Page 7 AN-6094 [STEP-2] Determine the DC Link Capacitor − min 2 ⋅ − ) and the DC Link Voltage Range LINE ⋅ It is typical to select the DC link capacitor as 2-3 µF per − 2.46(1 0.2) watt of input power for universal input range (90- ⋅...
- Page 8 AN-6094 added in to Equation (23), considering the V ripple (Design Example) caused by Burst Mode operation at no-load condition. For a 700 V MOSFET to have 35% margin on V the reflected output voltage should be: < × 0.65 700 455 ∴...
- Page 9 AN-6094 Once the t is determined at operating point B, the MOSFET conduction time is obtained as: − (24) ⋅ Then, the transformer primary-side inductance can be calculated as: ⋅ ⋅ (25) IN T Once transformer primary-side inductance determined, DCM operation at operating point C should be checked.
-
Page 10: Sensing Resistor
AN-6094 [STEP-5] Set the Output Current and V By setting the non conduction time at (Design Example) Sensing Resistor operating point B as 1.6 µs, the MOSFET conduction time is obtained as: The nominal output current is determined by the sensing resistor value and transformer turns ratio as: −... - Page 11 AN-6094 The recommendation for R design is to set R such [STEP-6] Design the RCD Clamping Circuit that the minimum on time curve of Figure 16 can be fully in the Primary Side utilized for the universal line range. It is typical to select When the MOSFET in the flyback converter is turned off, a such that I is around 180 µA for the minimum...
- Page 12 AN-6094 Once the power dissipation in the snubber is obtained, the π snubber resistor is calculated as: π (38) CLMP where R is the clamping resistor. The maximum ripple of the clamping capacitor voltage is obtained as: Δ (39) C R f CL s In general, 5~10% ripple of the selected capacitor voltage is reasonable.
- Page 13 AN-6094 where t is MOSFET conduction time minimum input of 100 mV, a post LC filter should be used. Two 330 µF voltage and maximum load condition, given as: capacitors and one 1.8 µH inductor are selected for the post LC filter. Then, the cutoff frequency of the LC filter is 9.2 kHz.
- Page 14 AN-6094 Note that the opto-coupler introduces a mid-frequency The original resonance period is (Design Example) measured as t =25 ns. pole due to the collector-emitter junction capacitance. Since the collector-base junction in a photo-transistor is Using a 1 nF test capacitor, the resonance period is used as a light detector;...
- Page 15 AN-6094 In STEP-8, the post LC filter is [STEP-11] Choose Startup Resistor for HV Pin (Design Example) designed with two 330 µF capacitors and a 1.8 µH Figure 22 shows the high-voltage (HV) startup circuit for inductor. Since the resonance frequency of the post LC FAN302 applications.
- Page 16 AN-6094 current-sensing voltage reaches 0.7 V. The flux density of [STEP-12] Protection Setting the transformer during the pulse-by-pulse current-limit mode should be checked to make sure that the flux density Output OVP: is below 0.4~0.42T to prevent severe core saturation. In STEP-5, the voltage divider for VS is determined such that VS sampling voltage is about 2.5 V in normal operation.
-
Page 17: Pcb Layout Guidelines
AN-6094 5. PCB Layout Guidelines Printed Circuit Board (PCB) layout and design are very As indicated by , the area enclosed by the important for switching power supplies where the voltage , should transformer auxiliary winding, D and C and current change with high dv/dt and di/dt. -
Page 18: Design Notes
AN-6094 6. Final Schematic of Design Example Figure 25 shows the final schematic of the 6 W charger Clamping circuit resistor R10 is adjusted to 390 kΩ design example. EI12.5 core is used for the transformer. based on test results from the actual power supply. Figure 26 shows the transformer winding structure. - Page 19 AN-6094 Terminal Insulation Wire Turns Start Pin End Pin Turns 2UEW 0.15*2 2UEW 0.12*1 Fly+ Fly- TEX-E 0.4*1 Specifications Remark Primary-Side Inductance 4－5 530 μH ±7% 100 kHz, 1 V Primary-Side Effective Leakage Inductance 4－5 52 μH ±5% Short one of the secondary windings Figure 27.
- Page 20 AN-6094 7. Test Results of Design Example To show the validity of the design procedure presented in Table 2. Loss Breakdown for Standby Power this application note, the converter of the design example Consumption was built and tested. All the circuit components are used as designed in the design example.
-
Page 21: Related Resources
AN-6094 8. Related Resources AN-4137 — Design guideline for Offline Flyback Converters Using Fairchild Power Switch (FPS™) FAN302HL/UL — mWSaver™ PWM Controller for Lower Standby Power Battery-Charger Applications FOD814 — Series, FOD817 Series 4-Pin High Operating Temperature Phototransistor Opto-Couplers 9. Author Hang-Seok Choi / Ph. - Page 22 FDA Class 3 medical devices or medical devices with a same or similar classification in a foreign jurisdiction or any devices intended for implantation in the human body. Should Buyer purchase or use ON Semiconductor products for any such unintended or unauthorized...