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Estimating the Significant Parameters of the Power Semiconductors Table 3. Estimating the Significant Parameters of the Power Semiconductors The magnetic elements within a switching power supply are used either for stepping-up or down a switched AC voltage, or for energy storage. In forward-mode topologies, the transformer is only used for stepping-up or down the AC voltage generated by the power switches. The output filter (the output inductor and capacitor) in forward-mode topologies...

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The boost-mode inductor must store enough energy to supply the output load for the entire switching period (ton + toff). Also, boost-mode converters are typically limited to a 50 percent duty cycle. There must be a time period when the inductor is permitted to empty itself of its energy. The boost converter is used for board-level (i.e., non-isolated) step-up applications and is limited to less than 100-150 watts due to high peak currents. Being a non-isolated converter, it is limited to input...

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Freq., UV Lockout, 150 ns Transient Response (1) Continuous at TA 25 C, Mounted on 1 square FR-4 or G10, VGS 10 V t < 10 seconds (1) Continuous at TA 25 C, Mounted on 1 square FR-4 or G10, VGS 10 V t < 10 seconds Figure 35. Typical 200 W ATX Forward Mode SMPS

Fully Released Technical Data

The Fully Released Technical Data document is for a product device that is in full production (i.e., fully released). It replaces the Advance Information document and represents a part that is fully qualified. The Fully Released Technical Data document is virtually the same document as the Product Preview and the Advance Information document with the exception that it provides information that is unavailable for a product in the early phases of development, such as complete parametric...

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The Waveforms of a Capacitive Input Filter A Power Factor Correction (PFC) circuit is a switching power converter, essentially a boost converter with a very wide input range, that precisely controls its input current on an instantaneous basis to match the waveshape and phase of the input voltage. This represents a zero degrees or 100 percent power factor and mimics a purely resistive load. The amplitude of the input current waveform is varied over longer time frames to maintain a...

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Automotive Workshop Layout

1600 Feehanville Drive Mount Prospect, IL 60056 website http www.component.talk.com Telephone 847-803-6100 Laying Out the Printed Circuit Board The printed circuit board (PCB) layout is the third critical portion of every switching power supply design in addition to the basic design and the magnetics design. Improper layout can adversely affect RFI radiation, component reliability, efficiency and stability. Every PCB layout will be different, but if the designer appreciates the common factors...

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Waveforms for a Continuous-Mode Boost Converter Common Switching Power Supply Topologies A topology is the arrangement of the power devices and their magnetic elements. Each topology has its own merits within certain applications. There are five major factors to consider when selecting a topology for a particular application. These are 1. Is input-to-output dielectric isolation required for the application This is typically dictated by the safety regulatory bodies in effect in the...

Turnoff Loss Switching Loss

Stresses and Losses within a Power MOSFET The forward conduction loss of a rectifier is shown in Figure 25. During turn-off, the rectifier exhibits a reverse recovery loss where minority carriers trapped within the P-N junction must reverse their direction and exit the junction after a reverse voltage is applied. This results in what appears to be a current flowing in reverse through the diode with a high reverse terminal voltage. The switching loss is the instantaneous product of...

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An Active Clamp Used in a One Transistor Forward or a Flyback Converter A quasi-resonant topology is designed to reduce or eliminate the frequency-dependent switching losses within the power switches and rectifiers. Switching losses account for about 40 of the total loss within a PWM power supply and are proportional to the switching frequency. Eliminating these losses allows the designer to increase the operating frequency of the switching power supply and so use smaller inductors...

Zener Clamp

Common Methods for Controlling Voltage Spikes and or RFI Figure 28. The Effects of a Snubber versus a Clamp Figure 28. The Effects of a Snubber versus a Clamp A lossless snubber is a snubber whose trapped energy is recovered by the power circuit. The lossless snubber is designed to absorb a fixed amount of energy from the transition of a switched AC voltage node. This energy is stored in a capacitor whose size dictates how much energy the snubber can absorb. A typical implementation...

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Figure 42. 80 W Power Factor Controller Reduced part count, low-cost solution. Complete semiconductor solution based around highly integrated MC33262. MC33262 Power Factor Controller MUR130 Axial Lead Ultrafast Recovery Rectifier (300 V) Coilcraft N2881-A Primary 62 turns of 22 AWG Secondary 5 turns of 22 AWG Core Coilcraft PT2510 Gap 0.072 total for a primary inductance (Lp) of 320 H Application Compact Power Factor Correction Low-cost system solution for boost mode follower. Meets IEC1000-3-2...

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Power Supply Battery Charger Regulator Control Circuit Surface Mount Ultrafast Rectifier 600 V Surface Mount Ultrafast Rectifier 200 V Zener Voltage Regulator Diode 5.1 V Zener Voltage Regulator Diode MMSZ18T1 Literature Available from ON Semiconductor These older Application Notes may contain part numbers that are no longer available, but the applications information may still be helpful in designing an SMPS. They are available through the Literature Distribution Center for ON Semiconductor at...

Switchmode Power Supply Reference Manual

SCILLC, 2002 Previous Edition 2000 All Rights Reserved'' ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC SCILLC . SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims...