0308 V

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...

2

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...

5

Efficient Safety Circuit for Electronic Ballast Easy to implement circuit to avoid thermal runaway when fluorescent lamp does not strike. Power devices do not have to be oversized - lower cost solution. Includes power factor correction. MC34262 Power Factor Controller MUR120 Ultrafast Rectifier (200 V) MJE18004D2 High Voltage Planar Bipolar Power Transistor (100 V) 1N4007 General Purpose Diode (1000 V) 1N5240B Zener Voltage Regulator Diode (10 V) 100 V MJD18002D2 MJB18004D2

A

Example of a Two-Phase Buck Converter with Voltage and Current Feedback There are three major methods of controlling a switching power supply. There are also variations of these control methods that provide additional protection features. One should review these methods carefully and then carefully review the controller IC data sheets to Table 1. Common Control Methods Used in ICs Voltage-mode control (see Figure 14) is typically used for forward-mode topologies. In voltage-mode...

Aaa

Power Ground (b) Proportionai Base Drive Circuit (Baker Ciamp) Power Ground (b) Proportionai Base Drive Circuit (Baker Ciamp) Figure 16. Driving a Bipolar Junction Transistor Power MOSFETs are the popular choices used as power switches and synchronous rectifiers. They are, on the surface, simpler to use than BJTs, but they have some hidden complexities. A simplified model for a MOSFET can be seen in Figure 17. The capacitances seen in the model are specified within the MOSFET data sheets, but...

Advance Information

The Advance Information document is for a device that is NOT fully qualified, but is in the final stages of the release process, and for which production is eminent. While the commitment has been made to produce the device, final characterization and qualification may not be complete. The Advance Information document is replaced with the Fully Released Technical Data document once the device part becomes fully qualified. The Advance Information document displays the following disclaimer at the...

C3

Figure 48. 110 W Output Flyback SMPS Figure 48. 110 W Output Flyback SMPS Off-line operation from 180 V to 280 Vac mains. Fixed frquency and stand-by mode. Automatically changes operating mode based on load requirements. Precise limiting of maximum power in fixed frequency mode. Built-in protection circuitry for current limitation, overvoltage detection, foldback, demagnetization and softstart. Reduced frequency in stand-by mode. MC44603P Enhanced Mixed Frequency Mode GreenLine PWM Controller

D

Snubbers and clamps are used for two very different purposes. When misapplied, the reliability of the semiconductors within the power supply is greatly jeopardized. A snubber is used to reduce the level of a voltage spike and decrease the rate of change of a voltage waveform. This then reduces the amount of overlap of the voltage and current waveforms during a transition, thus reducing the switching loss. This has its benefits in the Safe Operating Area (SOA) of the semiconductors, and it...

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...

Info

Schematic and Waveforms for a ZVS Quasi-Resonant Buck Converter Power Factor (PF) is defined as the ratio of real power to apparent power. In a typical AC power supply application where both the voltage and current are sinusoidal, the PF is given by the cosine of the phase angle between the input current and the input voltage and is a measure of how much of the current contributes to real power in the load. A power factor of unity indicates that 100 of the current is contributing to...

J4

Wide Mains 100 W TV SMPS with Secondary Reconfiguration for 1.3 W TV Stand-by Off power consumption 300mW drawn from the 8V output in pulsed mode. Pin 1.3W independent of the mains. Very low component count controller. Fail safe open feedback loop. Programmable pulsed-mode power transfer for efficient system stand-by mode. Stand-by losses independent of the mains value. Complete semiconductor solution.

L

-t + nit 0 < t < ton (eq. 2) During this period, energy is stored as magnetic flux within the core of the inductor. When the power switch is turned off, the core contains enough energy to supply the load during the following off period plus some reserve energy. When the power switch turns off, the voltage on the input side of the inductor tries to fly below ground, but is clamped when the catch diode D becomes forward biased. The stored energy then continues flowing to the output through...

Ncp1205

Quasi-resonant Operation, 250 mA Source Sink, 8-36 V Operation High Performance Current-Mode Controllers 500 kHz Freq., Totem Pole O P, Cycle-by-Cycle Current Limiting, UV Lockout Figure 39. AC DC Power Supply for Storage, Imaging & Entertainment Figure 39. AC DC Power Supply for Storage, Imaging & Entertainment Controller + 700 V Start-up & Power Switch, < 15 W

O

Turn-On with Clock Current-Mode Control Figure 15. Turn-On with Clock Current-Mode Control The Choice of Semiconductors Power Switches The choice of which semiconductor technology to use for the power switch function is influenced by many factors such as cost, peak voltage and current, frequency of operation, and heatsinking. Each technology has its own peculiarities that must be addressed during the design phase. There are three major power switch choices the bipolar junction...

Product Preview

A Product Preview is a summary document for a product device under consideration or in the early stages of development. The Product Preview exists only until an Advance Information document is published that replaces it. The Product Preview is often used as the first section or chapter in a corresponding reference manual. The Product Preview displays the following disclaimer at the bottom of the first page This document contains information on a product under development. ON Semiconductor...

Selector Guide

A Selector Guide is a document published, generally at set intervals, that contains key line-item, device-specific information for particular products or families. The Selector Guide is designed to be a quick reference tool that will assist a customer in determining the availability of a particular device, along with its key parameters and available packaging options. In essence, it allows a customer to quickly select a device. For detailed design and parametric information, the customer would...

Smpsrm

Reference Books Relating to Switching Power Supply Design Power Semiconductor Devices, PWS Publishing Co., Boston, 1996. 624 pages. Brown, Marty, Practical Switching Power Supply Design, Academic Press, Harcourt Brace Jovanovich, 1990. 240 pages. Brown, Marty Power Supply Cookbook, EDN Series for Design Engineers, ON Semiconductor Series in Solid State Electronics, Butterworth-Heinmann, MA, 1994. 238 pages High Frequency Switching Power Supplies Theory and Design, Second Edition, McGraw-Hill,...

Switching Loss

Stresses and Losses within Rectifiers the MOSFET should be placed in parallel with the synchronous MOSFET. The MOSFET does contain a parasitic body diode that could conduct current, but it is lossy, slow to turn off, and can lower efficiency by 1 to 2 . The lower turn-on voltage of the Schottky prevents the parasitic diode from ever conducting and exhibiting its poor reverse recovery characteristic. Using synchronous rectification, the conduction voltage can be reduced from 400 mV to...

T

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...

Tdk

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...

Time

A Basic Forward-Mode Converter and Waveforms (Buck Converter Shown) Its operation can be better understood when it is broken into two time periods when the power switch is turned on and turned off. When the power switch is turned on, the input voltage is directly connected to the input of the L-C filter. Assuming that the converter is in a steady-state, there is the output voltage on the filter's output. The inductor current begins a linear ramp from an initial current dictated by 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...

1

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...

Clr

Ben-Yaakov Sam, Gregory Ivensky, Passive Lossless Snubbers for High Frequency PWM Converters, Seminar 12, APEC 99. 2. Brown, Marty, Power Supply Cookbook, Butterworth-Heinemann, 1994, 2001. 3. Brown, Marty, Laying Out PC Boards for Embedded Switching Supplies, Electronic Design, Dec. 1999. 4. Martin, Robert F., Harmonic Currents, Compliance Engineering - 1999 Annual Resources Guide, Cannon Communications, LLC, pp. 103-107. 5. ON Semiconductor, Rectifier Applications Handbook, HB214 D, Rev. 2,...

Mqk

Schematic and Waveforms for a ZCS Quasi-Resonant Buck Converter Figure 31. Schematic and Waveforms for a ZCS Quasi-Resonant Buck Converter In this design, both the power switch and the catch diode operate in a zero current switching mode. Power is passed to the output during the resonant periods. So to increase the power delivered to the load, the frequency would increase, and vice versa for decreasing loads. In typical designs the frequency can change 10 1 over the ZCS supply's...

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...

Mje18204d2

ON Semiconductor's H2BIP process integrates a diode and bipolar transistor for a single package solution. Application AC-DC Battery Charger - Constant Current with Voltage Limit Figure 50. AC-DC Battery Charger - Constant Current with Voltage Limit 9.5 Watt capability for charging portable equipment. Light weight. ON Semiconductor Advantages Off the shelf components SPICE model available for MC33341 Figure 50. AC-DC Battery Charger - Constant Current with Voltage Limit

Orega Transformer G619100 Thomson Tv Components

70 W output power from 95 to 265 Vac. Load regulation 115 Vac 0.8 V. Cross regulation 115 Vac 0.2 V. Frequency 20 kHz fully stable. DIP16 or SO16 packaging options for controller. Meets IEC emi radiation standards. A narrow supply voltage design 80 W is also available. MC44603AP Enhanced Mixed Frequency Mode

Bzx84c5v1lt1

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...