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Application Notes

• Download
  Linear Technology Magazine Circuit Collection, Volume IV &mdash AN84
  PDF, 2.4 Mb, File published: Apr 1, 2000
  Application Note 84 is a collection of "power circuits" from the years 1996 through 1998 as seen in the pages of Linear Technology magazine. This Application Note collects circuits that can output tens of amps to circuits that can operate a handheld device for several years. In addition to a wide variety of traditional power supply circuits (Buck, Boost, Inverting, Flyback, Linear Regulators, etc.) we include circuits for charging batteries, several Power Management circuits as well as circuits that highlight a very low noise switching regulator.
  Extract from the document

  Application Note 84
  April 2000 Linear Technology Magazine Circuit Collection, Volume IV
  Power Products
  Richard Markell, Editor
  INTRODUCTION
  Application Note 84 is the fourth in a series that excerpts
  useful circuits from Linear Technology magazine to preserve them for posterity. This application note highlights
  “power” circuits from issue VI:1 (February 1996) through
  issue VIII:4 (November 1998). Another application note
  will feature data conversion, interface and signal processing circuits from the same era. Like its predecessor, AN 66,
  this Application Note includes circuits that can power
  most any system you can imagine, from “server” power
  supplies that generate in excess of 50 amps to micropower systems for portable and handheld equipment.
  Also included are power converters that can be voltage programmed using Intel’s VID code. Charge pump converters, linear regulators and battery charger circuits are
  included here, with Li-Ion batteries receiving extra attention. There are, of course, circuits that cannot be so simply
  categorized. Come browse. I’ll get out of the way and let
  the authors describe their creations.
  Note: Article Titles appear in this application note exactly
  as they originally appeared in Linear Technology magazine. This may result in some inconsistency in the usage
  of terminology. TABLE OF CONTENTS
  Introduction . 1
  REGULATORS—SWITCHING (BUCK)
  New LTCВ®1435–LTC1439 DC/DC Controllers Feature Value and Performance . 4 …

Design Notes

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  2-Step Power Conversion: Portable Power for the Future &mdash Design Solutions 8
  PDF, 119 Kb, File published: Apr 1, 1999
  Extract from the document

  Design Solutions 8
  April 1999
  2-Step Power Conversion:
  Portable Power for the Future
  As microprocessor operating voltages continue to
  decrease, power conversion for CPU core power is
  becoming a daunting challenge. A core power supply
  must have fast transient response, good efficiency, and
  low heat generation in the vicinity of the processor. These
  factors will soon force a move away from 1-step power
  conversion from battery or wall adapter to processor, to
  2-step conversion where the CPU core power is obtained
  from the 5V supply. While new to the portable arena,
  distributed power systems using 5V as a bus voltage have
  been used in large systems for many years. And although
  it may not be absolutely necessary to adopt this architecture in portables today, the clock is ticking for the old
  brute-force approach.
  Let’s start with the biggest argument against 2-step
  conversion: the perceived drop in efficiency and attendant heat generation in the 5V supply. Quick calculations may give a false impression that efficiency significantly
  decreases. It does not! Later in this paper we will show
  accurate calculations of efficiency for 2-step power conversion based on actual demo board measurements that
  show overall efficiency numbers equal to 1-step high
  efficiency converters. …

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  Sense Milliamps to Kiloamps and Digitize to 12 Bits &mdash DN227
  PDF, 73 Kb, File published: Apr 1, 2001
  Extract from the document

  Sense Milliamps to Kiloamps and Digitize to 12 Bits – Design Note 227
  Richard Markell and Glen Brisebois
  Introduction
  The LT®1787 high side current sense amplifier provides
  a precision measurement of current into or out of a
  power source. The part generates an output voltage that
  is directly proportional to the current flowing through
  an external current sense resistor. With a miniscule
  40ОјV (typical) input offset voltage, the LT1787 has a
  better than 12-bit, zero-cross accurate dynamic range
  at 250mV full-scale input. A hefty 60V maximum supply
  voltage specification allows the part to be used not only
  in low voltage battery applications but also in higher
  voltage telecom and industrial applications. Independent
  VEE and VBIAS pins make the application of the LT1787
  extremely versatile. Operation with an A/D Converter
  Figure 1 shows a detailed schematic of a high resolution
  (12-bit), bidirectional current-to-bits converter using
  an LT1787, the LT1783 SOT-23 1.2MHz micropower,
  rail-to-rail op amp and the LTC1404 SO-8 packaged,
  12-bit analog-to-digital converter with shutdown. The
  circuit, as shown, allows digitization of input current
  from approximately –3A to approximately 2A with …

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  Unique High Efficiency 12V Converter Operates with Inputs from 6V to 28V &mdash DN233
  PDF, 78 Kb, File published: Jun 2, 2001
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  advertisement Unique High Efficiency 12V Converter Operates
  with Inputs from 6V to 28V – Design Note 233
  Christopher B. Umminger
  Generating an output DC voltage from an input voltage
  that can vary both above and below the regulation point
  is a challenging power supply problem with a variety
  of solutions. Flyback or forward converters work well,
  but are difficult to use if a small and efficient solution
  is desired at high output currents. A cascade of two
  converters, such as a boost followed by a buck or linear
  regulator, is another possibility. Alternately, one can
  use a switching regulator in a SEPIC configuration that
  requires two inductors and an intermediate capacitor.
  These solutions are complex and have a high cost in
  components, board area and efficiency. However, one
  can also use the LTC В®1625 No RSENSE в„ў controller in a
  circuit that is capable of both up and down conversion
  and requires only a single inductor and no sense resistor. converter stage. During the п¬Ѓrst portion of each cycle,
  switches M1 and M3 are on while M2 is off. The input
  voltage is applied across the inductor and its current
  increases. After the LTC1625 current comparator trips,
  M1 and M3 are turned off and M2 and D2 conduct for
  the remainder of the cycle. During this time, current is …

Articles

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  The LTC1625 Current Mode DC/DC Controller Eliminates the Sense Resistor &mdash LT Journal
  PDF, 305 Kb, File published: Aug 1, 1998
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  LINEAR TECHNOLOGY
  AUGUST 1998
  IN THIS ISSUE…
  COVER ARTICLE
  The LTCВ®1625 Current Mode DC/DC
  Controller Eliminates the
  Sense Resistor . 1
  Christopher B. Umminger Issue Highlights . 2
  LTC in the News… . 2
  DESIGN FEATURES
  LTC1627 Monolithic Synchronous
  Step-Down Regulator Maximizes
  Single or Dual Li-Ion Battery Life
  . 5
  Jaime Tseng Clock-Tunable, High Accuracy,
  Quad 2nd Order, Analog Filter
  Building Blocks . 8
  Philip Karantzalis New DC/DC Controller Enables High
  Step-Down Ratios . 11
  Greg Dittmer VID Voltage Programmer for
  Intel Mobile Processors . 13
  Peter Guan Fixed Frequency, 500kHz, 4.5A StepDown Converter in an SO-8
  Operates from a 5V Input . 16 …

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  No Rsense Controller Delivers 12V and 100W at 97% Efficiency &mdash LT Journal
  PDF, 31 Kb, File published: Feb 1, 1999
  Extract from the document

  DESIGN IDEAS No RSENSE Controller Delivers 12V
  and 100W at 97% Efficiency by Christopher B.
  Umminger maximum temperature of 75В°C in a
  25В°C environment. L1 is a customwound inductor using fourteen turns
  of 15 gauge wire on a Magnetics, Inc.
  Kool Mµ® 77206-A7 core. The entire
  converter takes up a volume of only
  0.65in3 and processes an impressive
  150W per cubic inch.
  The circuit uses the LTC1625 No
  RSENSEв„ў controller to deliver the high
  output voltage with excellent efficiency. This controller provides true
  current mode control without using a
  sense resistor by monitoring the voltage drop across the power MOSFET
  switches. Eliminating the sense
  resistor saves board space and
  improves efficiency. In this application, a 0.01Ω sense resistor would
  dissipate about 0.7W at full load.
  Many current mode controllers use
  a sense resistor in series with the
  inductor. Unfortunately, they must
  restrict the maximum output voltage RF 1Ω
  CF …

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  20A Constant Current Source/Battery Charger is 95% Efficient &mdash LT Journal
  PDF, 109 Kb, File published: Jun 1, 1999
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  DESIGN IDEAS 20A Constant Current Source/Battery
  by Goran Perica
  Charger is 95% Efficient
  Introduction
  have a limited bandwidth of 20kHz to
  50kHz; as a result, a current regulator based on such a sensor has a slow
  transient response. As far as the cost
  and simplicity are concerned, current sense resistors are the better
  choice, as long as power dissipation
  is within the acceptable limits. The
  power dissipation in a current sense
  resistor depends on the current and
  the voltage across the resistor. Hence,
  keeping the voltage drop across the
  current sense resistor low is very
  important. The circuit in Figure 1 is a
  constant-current (CC), constant-voltage (CV) DC/DC converter that
  generates 20A of output current and
  maintains efficiency greater than 95%
  with a 24V input and 12.6V output. Generating precise, high DC currents
  presents a challenge due to the need
  for a current sensor that is sufficiently precise and low in cost and
  power dissipation. A current sense …

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  Single-Inductor, Positive-Output Buck/Boost Converter Uses No Rsense Controller &mdash LT Journal
  PDF, 136 Kb, File published: Jun 1, 1999
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  DESIGN IDEAS Single-Inductor, Positive-Output
  Buck/Boost Converter Uses
  No RSENSE Controller
  by Christopher B. Umminger DESIGN IDEAS
  Single-Inductor, Positive-Output
  Buck/Boost Converter Uses
  No R SENSE Controller .28
  Christopher B. Umminger Designing the L T1167
  Instrumen tation Amplifier into
  a Single 5V Supply Application . 29
  Adolfo A. Garcia Low Voltage PowerPath Driver
  Switches from a 3.3V or 5V Supply
  to Battery Backup .31
  Peter Guan and Tim Skovmand 20A Constant Current Sourc e/Battery
  Charger is 95% Efficient .32
  Goran Perica LTC2400 Differential
  Bridge Digitizers .34
  Kevin R. Hoskins and Derek Redmayne 4.5 Вµ A Li-Ion
  Battery Protection Circu it .36
  Albert Lee provides a 12V output with inputs
  that can range from 18V down to 6V.
  All of the circuitry to the left of the
  inductor is identical to that of a typical buck converter implemented with …

Model Line

Manufacturer's Classification

• Power Management > Switching Regulator > Step-Down (Buck) Regulators > External Power Switch Buck Controllers