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LT1054L

Application Notes

• Download
  Micropower Circuits for Signal Conditioning &mdash AN23
  PDF, 2.2 Mb, File published: Apr 1, 1987
  Low power operation of electronic apparatus has become increasingly desirable. AN23 describes a variety of low power circuits for transducer signal conditioning. Also included are designs for data converters and switching regulators. Three appended sections discuss guidelines for micropower design, strobed power operation and effects of test equipment on micropower circuits.
  Extract from the document

  Application Note 23
  April 1987
  Micropower Circuits for Signal Conditioning
  Jim Williams
  Low power operation of electronic apparatus has become
  increasingly desirable. Medical, remote data acquisition,
  power monitoring and other applications are good candidates for battery driven, low power operation. Micropower
  analog circuits for transducer-based signal conditioning
  present a special class of problems. Although micropower
  ICs are available, the interconnection of these devices to
  form a functioning micropower circuit requires care. (See
  Box Sections, “Some Guidelines for Micropower Design
  and an Example” and “Parasitic Effects of Test Equipment
  on Micropower Circuits.”) In particular, trade-offs between
  signal levels and power dissipation become painful when
  performance in the 10-bit to 12-bit area is desirable. Additionally, many transducers and analog signals produce +V inherently small outputs, making micropower requirements complicate an already difficult situation. Despite the
  problems, design of such circuits is possible by combining
  high performance micropower ICs with appropriate circuit
  techniques.
  Platinum RTD Signal Conditioner
  Figure 1 shows a simple circuit for signal conditioning
  a platinum RTD. Correction for the platinum sensor’s
  nonlinear response is included. Accuracy is 0.25В°C over …

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  Some Thoughts on DC-DC Converters &mdash AN29
  PDF, 1.2 Mb, File published: 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.
  Extract from the document

  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, File published: 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.
  Extract from the document

  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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  A Monolithic Switching Regulator with 100ВµV Output Noise &mdash AN70
  PDF, 1.7 Mb, Language: en, File published: Oct 1, 1997
  This publication details circuitry and applications considerations for the LT1533 low noise switching regulator. Eleven DC/DC converter circuits are presented, some offering <100µV output noise in a 100MHz bandwidth. Tutorial sections detail low noise DC/DC design, measurement, probing and layout techniques, and magnetics selection.
  Extract from the document

  Application Note 70
  October 1997
  A Monolithic Switching Regulator with 100ВµV Output Noise
  “Silence is the perfectest herald of joy .”
  Jim Williams INTRODUCTION
  Size, output flexibility and efficiency advantages have
  made switching regulators common in electronic apparatus. The continued emphasis on these attributes has
  resulted in circuitry with 95% efficiency that requires
  minimal board area. Although these advantages are welcome, they necessitate compromising other parameters. back to the driving source (“reflected” noise) and it is
  radiated. The multiple transmission paths combine with
  the high frequency content to make noise suppression
  difficult. Unconscionable amounts of bypass capacitors,
  ferrite beads, shields, Mu-metal and aspirin have been
  expended in attempts to ameliorate noise-induced effects. Switching Regulator “Noise”
  Something commonly referred to as “noise” is a primary
  concern. The switched mode power delivery that permits
  the aforementioned advantages also creates wideband
  harmonic energy. This undesirable energy appears as
  radiated and conducted components commonly labeled
  as “noise.” Actually, switching regulator output “noise” is
  not really noise at all, but coherent, high frequency residue
  directly related to the regulatorвЂ^TMs switching.1 Figure 1
  shows typical switching regulator output noise. Two distinct characteristics are present. The slow, ramping output …

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  Current Sources for Fiber Optic Lasers: A Compendium of Pleasant Current Events &mdash AN90
  PDF, 409 Kb, File published: Apr 1, 2002
  A large group of fiber optic lasers are powered by DC current. Laser drive is supplied by a current source with modulation added to the signal. The current source, although conceptually simple, constitutes an extraordinarily tricky design problem. There are a number of practical requirements for a fiber optic current source and failure to consider them can cause laser and/or optical component destruction. This application note describes ten laser current source circuits with a range of capabilities. High and low current types are presented, along with designs for grounded anode, cathode or floating operation. Each circuit also includes laser protection features. Appended sections cover laser load simulation and current source noise measurement techniques.
  Extract from the document

  Application Note 90
  April 2002
  Current Sources for Fiber Optic Lasers
  A Compendium of Pleasant Current Events
  Jim Williams, Linear Technology Corporation
  INTRODUCTION
  A large group of fiber optic lasers are powered by DC
  current. Laser drive is supplied by a current source with
  modulation added further along the signal path. The
  current source, although conceptually simple, constitutes
  an extraordinarily tricky design problem. There are a
  number of practical requirements for a fiber optic current
  source and failure to consider them can cause laser and/
  or optical component destruction. Protection features must be included to prevent laser and
  optical component damage. The laser, an expensive and
  delicate device, must be protected under all conditions,
  including supply ramp up and down, improper control
  input commands, open or intermittent load connections
  and “hot plugging.”
  Detailed Discussion of Performance Issues Design Criteria for Fiber Optic Laser Current Sources It is useful to expand on the above cursory discussion to
  clarify design goals. As such, each previously called out
  issue is treated in greater detail below. Figure 1 shows a conceptual laser current source. Inputs
  include a current output programming port, an output …

Articles

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  Switched Capacitor Voltage Regulator Provides Current Gain &mdash LT Journal
  PDF, 44 Kb, File published: Feb 1, 1999
  Extract from the document

  DESIGN IDEAS Switched Capacitor Voltage Regulator
  Provides Current Gain
  by Jeff Witt
  A switched capacitor voltage
  inverter is normally used to generate
  a negative supply voltage from a positive input supply. The negative supply
  current is equal in magnitude to the
  current drawn from the input. This
  design idea describes two circuits that
  use an inverter to double the current
  between the input and output,
  increasing efficiency and eliminating
  heat dissipation problems. V VIN VIN
  CAP+ GND CAP– CAP–
  VOUT VOUT –V
  I Figure 1. Rewiring a switched capacitor inverter for step-down regulation results in
  a current gain of 2. charging C1 into the output. The current delivered to the output is
  continuous and equal to twice the
  average input current. Because the
  output current is continuous, the
  output voltage ripple is low. Note that
  C1 and COUT do not need to be
  matched, as their voltages are equalized on each cycle. …

Model Line

Manufacturer's Classification

• Power Management > Inductorless (Charge Pump) DC/DC Converters > Unregulated Doubling/Inverting Charge Pumps | Regulated Step-Up Charge Pumps
• Space & Harsh Environment > Military Hermetic (M)