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• 预览并下载
  LT1070 Design Manual &mdash AN19
  PDF, 656 Kb, 语言: en, 档案已发布: Jun 1, 1986, 页数: 80
  Application Note 19. This design manual is an extensive discussion of all standard switching configurations for the LT1070; including buck, boost, flyback, forward, inverting and "Cuk." The manual includes comprehensive information on the LT1070, the external components used with it, and complete formulas for calculating component values.
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  Application Note 19
  June 1986
  LT1070 Design Manual
  Carl Nelson
  INTRODUCTION
  Three terminal monolithic linear voltage regulators appeared almost 20 years ago, and were almost immediately
  successful for a variety of reasons. In particular, there
  were relatively few engineers capable of designing a good
  linear voltage regulator. The new devices were also easy to
  use, and inexpensive. In currently popular parlance they
  were "expert systems," containing a good deal of their
  designer's knowledge in silicon form. Because of these
  advantages, the regulators quickly eclipsed discrete and
  earlier monolithic building blocks and dominated the
  market.
  More recently, there has been increasing interest in switching-based regulators. Switching regulators, with their
  high efficiency and small size, are increasingly desirable
  as overall package sizes have shrunk. Unfortunately, switching regulators are also one of the most difficult linear
  circuits to design. Mysterious modes, sudden failures,
  peculiar regulation characteristics and just plain explosions are common occurrences during the design of a
  switching regulator.
  Most switching regulator ICs are building blocks. Many
  discrete components are required, and substantial expertise is assumed on the part of the user. Some newer …

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  Switching Regulators for Poets: A Gentle Guide for the Trepidatious &mdash AN25
  PDF, 359 Kb, 档案已发布: Sep 2, 1987
  Subtitled "A Gentle Guide for the Trepidatious," this is a tutorial on switching regulator design. The text assumes no switching regulator design experience, contains no equations, and requires no inductor construction to build the circuits described. Designs detailed include flyback, isolated telecom, off-line, and others. Appended sections cover component considerations, measurement techniques and steps involved in developing a working circuit.
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  Application Note 25
  September 1987 Switching Regulators for Poets
  A Gentle Guide for the Trepidatious
  Jim Williams
  The above title is not happenstance and was arrived at after
  considerable deliberation. As a linear IC manufacturer, it is
  our goal to encourage users to design and build switching
  regulators. A problem is that while everyone agrees that
  working switching regulators are a good thing, everyone
  also agrees that they are difficult to get working. Switching
  regulators, with their high efficiency and small size, are
  increasingly desirable as overall package sizes shrink.
  Unfortunately, switching regulators are also one of the
  most difficult linear circuits to design. Mysterious modes,
  sudden, seemingly inexplicable failures, peculiar regulation characteristics and just plain explosions are common
  occurrences. Diodes conduct the wrong way. Things get
  hot that shouldn’t. Capacitors act like resistors, fuses
  don’t blow and transistors do. The output is at ground, and
  the ground terminal shows volts of noise.
  Added to this poisonous brew is the regulator’s feedback
  loop, sampled in nature and replete with uncertain phase
  shifts. Everything, of course, varies with line and load
  conditions— and the time of day, or so it seems. In the face …

• 下载
  Some Thoughts on DC-DC Converters &mdash AN29
  PDF, 1.2 Mb, 档案已发布: Oct 1, 1988
  This note examines a wide range of DC/DC converter applications. Single inductor, transformer, and switched-capacitor converter designs are shown. Special topics like low noise, high efficiency, low quiescent current, high voltage, and wide-input voltage range converters are covered. Appended sections explain some fundamental properties of different types of converters.
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  Application Note 29
  October 1988
  Some Thoughts on DC/DC Converters
  Jim Williams and Brian Huffman
  INTRODUCTION
  Many systems require that the primary source of DC power
  be converted to other voltages. Battery driven circuitry is
  an obvious candidate. The 6V or 12V cell in a laptop computer must be converted to different potentials needed for
  memory, disc drives, display and operating logic. In theory,
  AC line powered systems should not need DC/DC converters
  because the implied power transformer can be equipped
  with multiple secondaries. In practice, economics, noise
  requirements, supply bus distribution problems and other
  constraints often make DC/DC conversion preferable. A
  common example is logic dominated, 5V powered systems
  utilizing В±15V driven analog components.
  The range of applications for DC/DC converters is large,
  with many variations. Interest in converters is commensurately quite high. Increased use of single supply powered
  systems, stiffening performance requirements and battery
  operation have increased converter usage.
  Historically, efficiency and size have received heavy emphasis. In fact, these parameters can be significant, but
  often are of secondary importance. A possible reason
  behind the continued and overwhelming attention to size …

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  Switching Regulator Circuit Collection &mdash AN30
  PDF, 606 Kb, 档案已发布: Feb 1, 1989
  Switching regulators are of universal interest. Linear Technology has made a major effort to address this topic. A catalog of circuits has been compiled so that a design engineer can swiftly determine which converter type is best. This catalog serves as a visual index to be browsed through for a specific or general interest.
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  Application Note 30
  February 1989
  Switching Regulator Circuit Collection
  John Seago
  Switching regulators are of universal interest. Linear
  Technology has made a major effort to address this topic.
  A catalog of circuits has been compiled so that a design
  engineer can swiftly determine which converter type is
  best. This catalog serves as a visual index to be browsed
  through for a specific or general interest. The catalog is organized so that converter topologies can
  be easily found. There are 12 basic circuit categories:
  Battery, Boost, Buck, Buck-Boost, Flyback, Forward, High
  Voltage, Multioutput, Off Line, Preregulator, Switched
  Capacitor and Telecom. Additional circuit information can
  be located in the references listed in the index. The
  reference works as follows, i.e., AN8, Page 2 = Application
  Note 8, Page 2; LTC1044 DS = LTC1044 data sheet;
  DN17 = Design Note 17. DRAWING INDEX
  FIGURE TITLE FIGURE # PAGE REFERENCE/SOURCE Battery
  2A Converter with 150ВµA Quiescent Current (6V to 12V)
  200mA Output Converter (1.5V to 5V)
  Up Converter (6V to 15V)
  Regulated Up Converter (5V to 10V) …

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  Linear Circuits for Digital Systems &mdash AN31
  PDF, 1.5 Mb, 档案已发布: Feb 2, 1989
  Subtitled "Some Affable Analogs for Digital Devotees," discusses a number of analog circuits useful in predominantly digital systems. VPP generators for flash memories receive extensive treatment. Other examples include a current loop transmitter, dropout detectors, power management circuits, and clocks.
• 下载
  Step Down Switching Regulators &mdash AN35
  PDF, 6.2 Mb, 档案已发布: Aug 1, 1989
  Discusses the LT1074, an easily applied step-down regulator IC. Basic concepts and circuits are described along with more sophisticated applications. Six appended sections cover LT1074 circuitry detail, inductor and discrete component selection, current measuring techniques, efficiency considerations and other topics.
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  Application Note 35
  August 1989
  Step-Down Switching Regulators
  Jim Williams
  lost in this voltage-to-current-to-magnetic п¬Ѓeld-to-current-to-charge-to-voltage conversion. In practice, the
  circuit elements have losses, but step-down efficiency is
  still higher than with inherently dissipative (e.g., voltage
  divider) approaches. Figure 2 feedback controls the basic
  circuit to regulate output voltage. In this case switch ontime (e.g., inductor charge time) is varied to maintain the
  output against changes in input or loading.
  REGULATED
  OUTPUT IN PULSE
  WIDTH
  MODULATOR Figure 1 is a conceptual voltage step-down or “buck”
  circuit. When the switch closes the input voltage appears
  at the inductor. Current flowing through the inductor-capacitor combination builds over time. When the switch
  IN OUT AN35 F01 Figure 1. Conceptual Voltage Step-Down (“Buck”) Circuit opens current flow ceases and the magnetic field around
  the inductor collapses. Faraday teaches that the voltage
  induced by the collapsing magnetic п¬Ѓeld is opposite to the
  originally applied voltage. As such, the inductor’s left side
  heads negative and is clamped by the diode. The capacitors accumulated charge has no discharge path, and a DC
  potential appears at the output. This DC potential is lower
  than the input because the inductor limits current during …

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  Parasitic Capacitance Effects in Step-Up Transformer Design &mdash AN39
  PDF, 764 Kb, 档案已发布: Feb 3, 1990
  This note explores the causes of the large resonating current spikes on the leading edge of the switch current waveform. These anomalies are exacerbated in very high voltage designs.
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  Application Note 39
  February 1990
  Parasitic Capacitance Effects
  in Step-Up Transformer Design
  Brian Huffman
  One of the most critical components in a step-up design
  like Figure 1 is the transformer. Transformers have parasitic components that can cause them to deviate from
  their ideal characteristics, and the parasitic capacitance
  associated with the secondary can cause large resonating
  current spikes on the leading edge of the switch current
  waveform. These spikes can cause the regulator to exhibit
  erratic operating conditions that manifests itself as duty
  cycle instability. This effect is exacerbated in very high
  voltage designs. Attention to transformer design will cure
  this problem. Figure 2 shows the high frequency current paths of the
  parasitic capacitors. In the analysis of operation assume
  the input and output voltages are at AC ground. Thus, the
  parasitic capacitors are all in parallel. The transformer’s
  secondary provides the AC current path for these capacitors. The current flowing through the secondary produces
  N times the current in the primary. As the parasitic capacitance and turns ratio increase, the primary current
  becomes progressively larger. D1
  MUR1100
  VIN …

• 下载
  LT1074/LT1076 Design Manual &mdash AN44
  PDF, 477 Kb, 档案已发布: Sep 1, 1991
  This note discusses the use of the LT1074 and LT1076 high efficiency switching regulators. These regulators are specifically designed for ease of use. This application note is intended to eliminate the most common errors that customers make when using switching regulators as well as offering insight into the inner workings of switching designs. There is an entirely new treatment of inductor design based upon simple mathematical formulas that yield direct results. There are extensive tutorial sections devoted to the care and feeding of the Positive Step- Down (Buck) Converter, the Tapped Inductor Buck Converter, the Positive-to-Negative Converter and the Negative Boost Converter. Additionally, many troubleshooting hints are included as well as oscilloscope techniques, soft-start architectures, and micropower shutdown and EMI suppression methods.
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  Application Note 44
  September 1991
  LT1074/LT1076 Design Manual
  Carl Nelson
  INTRODUCTION
  The use of switching regulators increased dramatically in
  the 1980’s and this trend remains strong going into the
  90s. The reasons for this are simple; heat and efficiency.
  Today’s systems are shrinking continuously, while simultaneously offering greater electronic “horsepower.” This
  combination would result in unacceptably high internal
  temperatures if low efficiency linear supplies were used.
  Heat sinks do not solve the problem in general because
  most systems are closed, with low thermal transfer from
  “inside” to “outside.”
  Battery-powered systems need high efficiency supplies for
  long battery life. Topological considerations also require
  switching technology. For instance, a battery cannot
  generate an output higher than itself with linear supplies.
  The availability of low cost rechargeable batteries has created a spectacular rise in the number of battery-powered
  systems, and consequently a matching rise in the use of
  switching regulators.
  The LTВ®1074 and LT1076 switching regulators are designed
  specifically for ease of use. They are close to the ultimate …

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  Efficiency and Power Characteristics of Switching Regulator Circuits &mdash AN46
  PDF, 2.6 Mb, 档案已发布: Nov 1, 1991
  Efficiency varies for different DC/DC converters. This application note compares the efficiency characteristics of some of the more popular types. Step-up, step-down, flyback, negative-to-positive, and positive-to-negative are shown. Appended sections discuss how to select the proper aluminum electrolytic capacitor and explain power switch and output diode loss calculations.

设计须知

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  Achieving Microamp Quiescent Current in Switching Regulators &mdash DN11
  PDF, 95 Kb, 档案已发布: Jun 1, 1988
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  advertisement Achieving Microamp Quiescent Current in Switching Regulators
  Design Note 11
  Jim Williams
  Many battery powered applications require very wide
  ranges of power supply output current. Normal conditions require currents in the ampere range, while
  standby or “sleep” modes draw only microamperes.
  A typical lap top computer may draw 1 to 2 amperes
  running while needing only a few hundred microamps
  for memory when turned off. In theory, any switching
  regulator designed for loop stability under no-load
  conditions will work. In practice, a regulator’s relatively
  large quiescent current may cause unacceptable battery
  drain during low output current intervals.
  Figure 1 shows a typical flyback regulator. In this
  case the 6V battery is converted to a 12V output by
  the inductive flyback voltage produced each time the
  LT®1070’s VSW pin is internally switched to ground. An
  internal 40kHz clock produces a flyback event every
  25μs. The energy in this event is controlled by the IC’s
  internal error amplifier, which acts to force the feedback
  (FB) pin to a 1.23V reference. The error amplifiers high
  impedance output (the VC pin) uses an RC damper for
  stable loop compensation. …

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  Telephone Ring-Tone Generation &mdash DN134
  PDF, 80 Kb, 档案已发布: Aug 1, 1996
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  Telephone Ring-Tone Generation – Design Note 134
  Dale Eagar
  Requirements
  When your telephone rings, exactly what is the phone
  company doing? This question comes up frequently, as
  it seems everyone is becoming a telephone company.
  Deregulation opens many new opportunities, but if you
  want to be the phone company you have to ring bells.
  An Open-Architecture Ring-Tone Generator
  Here is a design that you can own, tailor to your specific
  needs, layout on your circuit board and put on your bill
  of materials. Finally, you will be in control of the black
  magic (and high voltages) of ring-tone generation.
  Not Your Standard Bench Supply
  Ring-tone generation requires not one but two high
  voltages, 60VDC and – 180VDC (this arises from the
  need to put 87VRMS on –48VDC). Figure 1 details the
  switching power supply that delivers the volts needed
  to run the ring-tone circuit. This switcher can be powered from any voltage from 5V to 30V and shuts down
  when not in use. Figure 2 is the build diagram of the
  transformer used in the switching power supply.
  60V
  MUR160 = PRIMARY GROUND T1 2 = SECONDARY GROUND + …

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  A Battery Powered Lap Top Computer Power Supply &mdash DN18
  PDF, 90 Kb, 档案已发布: Dec 1, 1988
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  A Battery Powered Lap Top Computer Power Supply
  Design Note 18
  Brian Huffman
  Most battery powered lap top computers require regulated multiple output potentials. Problems associated
  with such a supply include magnetic and snubber design,
  loop compensation, short circuit protection, size and
  efficiency. Typical output power requirements include
  5V @ 1A for memory and logic circuitry and В±12V
  @ 300mA to drive the analog components. Primary
  power may be either a 6V or 12V battery. The circuit
  in Figure 1 meets all these requirements. The LTВ®1071
  simplifies the power supply design by integrating most
  of the switching regulator building blocks. Also, the
  off-the-shelf transformer eliminates all the headaches
  associated with the magnetic design.
  The circuit is a basic flyback regulator. The transformer
  transfers the energy from the 12V input to the 5V and
  В±12V outputs. Figure 2 shows the voltage (trace A) and
  the current (trace B) waveforms at the VSW pin. The
  VSW output is a collector of a common emitter NPN,
  so current flows through it when it is low. The circuit’s
  40kHz repetition rate is set by the LT1071’s internal
  oscillator. During the VSW (trace A) “on” time, the input …

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  Floating Input Extends Regulator Capabilities &mdash DN21
  PDF, 71 Kb, 档案已发布: Apr 1, 1989
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  advertisement Floating Input Extends Regulator Capabilities – Design Note 21
  Brian Huffman
  however, if the secondary windings are isolated from
  one another, a low dropout positive voltage regulator
  can be used for negative regulation (Figure 1). Many applications require circuit performance that is
  unachievable with conventional regulator design. This
  results in added complexity to the circuit. However, some
  problems can easily be solved by floating the input to
  the regulator. A floating input can either be a battery, or
  a secondary winding that is galvanically isolated from
  all other windings. With this method high efficiency
  negative voltage regulation, high voltage regulation, and
  low saturation loss positive buck switching regulator
  can all be achieved easily. In this circuit the LTВ®1086 servos the voltage between
  the output and the adjust pin to 1.25V. The positive
  regulation is accomplished by conventional regulator
  design. Negative voltage regulation is achieved by
  connecting the output of the positive voltage regulator
  to ground. The VIN pin floats to 1.5V or greater, above
  ground. This technique can be used with any positive
  voltage regulator, although highest efficiency occurs
  with low dropout types. Low dropout negative voltage regulators are not currently available. This would seem to preclude high efficiency negative linear regulators. Such regulation is
  frequently desired in switching supply post regulators; L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks …

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  Inductor Selection for LT 1070 Switching Regulators &mdash DN8
  PDF, 114 Kb, 档案已发布: Mar 1, 1988
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  advertisement Inductor Selection for Switching Regulators
  Design Note 8
  Jim Williams
  A common problem area in switching regulator design
  is the inductor, and the most common difficulty is
  saturation. An inductor is saturated when it cannot
  hold any more magnetic flux. As an inductor arrives
  at saturation it begins to look more resistive and less
  inductive. Under these conditions current flow is limited
  only by the inductor’s DC copper resistance and the
  source capacity. This is why saturation often results
  in destructive failures.
  While saturation is a prime concern, cost, heating,
  size, availability and desired performance are also
  significant. Electromagnetic theory, although applicable
  to these issues, can be confusing, particularly to the
  non-specialist.
  Practically speaking, an empirical approach is often a
  good way to approach inductor selection. It permits real time analysis under actual circuit operating conditions
  using the ultimate simulator—a breadboard. If desired,
  inductor design theory can be used to augment or
  confirm experimental results.
  Figure 1 shows a typical flyback regulator utilizing the …

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• Power Management > Switching Regulator > SEPIC Regulators
• Power Management > Switching Regulator > Step-Up (Boost) Regulators > Internal Power Switch Boost