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Notas de aplicación

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  Power Conditioning for Notebook and Palmtop Systems &mdash AN51
  PDF, 260 Kb, Archivo publicado: agosto 3, 1992
  Notebook and palmtop systems need a number of voltages developed from a battery. Competitive solutions require small size, high efficiency and light weight. This publication includes circuits for high efficiency 5V and 3.3V switching and linear regulators, back light display drivers and battery chargers. All the circuits are specifically tailored for the requirements outlined above.
  Extracto del documento

  Application Note 51
  August 1992
  Power Conditioning for Notebook and Palmtop Systems
  Robert Dobkin
  Carl Nelson
  Dennis O’Neill
  Steve Pietkiewicz
  Tim Skovmand
  Milt Wilcox
  INTRODUCTION Battery systems include NiCad, nickel-hydride, lead acid,
  and rechargeable lithium, as well as throw-away alkaline
  batteries. The ability to power condition a wide range
  of batteries makes the ultimate product much more
  attractive because power sources can be interchanged,
  increasing overall system versatility. a very high efficiency (Figure 1) 5V or 3.3V step-down
  (buck) switching regulator. These regulators feature a
  low-loss saturating NPN switch that is normally configured with the negative terminal (emitter) at ground. The
  LT1432 allows the switch to be floated as required in a
  step-down converter, yet still provides full switch saturation for highest efficiency.
  Burst ModeTM is a trademark of Linear Technology Coporation. 100
  NORMAL MODE
  (USE AMPS SCALE)
  90 EFFICIENCY (%) Notebook and palmtop systems need a multiplicity of …

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  5V to 3.3V Converters for Microprocessor Systems &mdash AN58
  PDF, 310 Kb, Archivo publicado: sept 1, 1993
  Many popular microprocessors operate from 3.3V supplies, yet they are used in systems where the predominate source of power is 5V. AN58 presents a collection of both linear and switching regulator solutions for conversion of 5V to 3.3V at currents ranging from 100mA to 20A. Applications information and a comparison of various bypass capacitor types is included. Most of the designs can be easily modified for other intermediate voltages such as 3.45V, 3.7V, and 4.1V.
  Extracto del documento

  Application Note 58
  September 1993
  5V to 3.3V Converters for Microprocessor Systems
  Robert Dobkin, Mitchell Lee, Dennis O'Neill and Milt Wilcox
  Introduction Linear Regulators The new generation of high performance microprocessors are built on dense, low breakdown voltage processes
  in order to accommodate increased transistor counts.
  These new processors require high current power at 3.3V,
  developed from the 5V input used to power the rest of the
  system. Special techniques are required to ensure proper
  operation of the microprocessor and good heat dissipation within the computer system. Table 1 shows the range of components available for linear
  regulation of 3.3V with a 5V input. With only 1.7V of
  headroom, low dropout is essential. Low dropout regulators are available delivering currents from 125mA to 7.5A,
  allowing almost any microprocessor to be powered with a
  local 3.3V generation circuit. The first four devices (LT1020,
  LT1120, LT1121 and LT1129) are PNP micropower low
  dropout regulators. Since PNP transistors are much larger
  than monolithic NPNs, higher current regulators use an
  NPN pass device. The LT1117, LT1086, LT1083 through
  LT1085, and LT1087 all use NPN pass devices. The NPN
  structure requires about 1.2V headroom compared to the
  400mV to 500mV dropout typical of PNP regulators, and
  ground current of 5mA or 10mA, independent of output
  current. Because of this constant quiescent current, the …

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  A Fourth Generation of LCD Backlight Technology &mdash AN65
  PDF, 5.9 Mb, Archivo publicado: nov 1, 1995
  This publication, LTC's fourth effort devoted to LCD backlighting in as many years, treats the subject comprehensively. The text considers lamps, display and layout induced losses, circuitry, efficiency related issues, optimization and measurement techniques. Twelve appended sections cover lamp types, mechanical design, electrical and photometric measurement, layout, circuitry and related topics.
  Extracto del documento

  Application Note 65
  November 1995
  A Fourth Generation of LCD Backlight Technology
  Component and Measurement Improvements Refine Performance
  Jim Williams PREFACE
  Current generation portable computers and instruments
  utilize backlit LCDs (liquid crystal displays). These displays
  have also appeared in applications ranging from medical
  equipment to automobiles, gas pumps and retail terminals.
  Cold cathode fluorescent lamps (CCFLs) provide the highest available efficiency for backlighting the display. These
  lamps require high voltage AC to operate, mandating an
  efficient high voltage DC/AC converter. In addition to good
  efficiency, the converter should deliver the lamp drive in
  sine wave form. This is desirable to minimize RF emissions.
  Such emissions can cause interference with other devices,
  as well as degrading overall operating efficiency. The sine
  wave excitation also provides optimal current-to-light
  conversion in the lamp. The circuit should permit lamp
  control from zero to full brightness with no hysteresis or
  “pop-on,” and must also regulate lamp intensity vs power
  supply variations.
  The small size and battery-powered operation associated
  with LCD equipped apparatus mandate low component …

Notas de Diseño

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  Techniques for Deriving 3.3V from 5V Supplies &mdash DN74
  PDF, 73 Kb, Archivo publicado: sept 1, 1993
  Extracto del documento

  advertisement Techniques for Deriving 3.3V from 5V Supplies – Design Note 74
  Mitchell Lee
  Microprocessor chip sets and logic families that operate from 3.3V supplies are gaining acceptance in both
  desktop and portable computers. Computing rates, and
  in most cases, energy consumed by these circuits show
  a strong improvement over 5V technology. The main
  power supply in most systems is still 5V, necessitating
  a local 5V to 3.3V regulator.
  Linear regulators are viable solutions at lower (IO ≤ 1A)
  currents, but they must have a low dropout voltage in
  order to maintain regulation with a worst-case input
  5 4.5V TO 5.5V IN OUT 1 + LT1129-3.3
  4 SHUTDOWN SENSE 2 GND 3.3V OUT
  700mA
  3.3ОјF
  SOLID TANTALUM of only 4.5V. Figure 1 shows a circuit that converts a
  4.5V minimum input to 3.3V with an output tolerance
  of only 3% (100mV). The LTВ®1129-3.3 can handle up to
  700mA in surface mount configurations, and includes
  both 16ОјA shutdown and 50ОјA standby currents for
  system sleep modes. Unlike other linear regulators, the
  LT1129-3.3 combines both low dropout and low voltage
  operation. Small input and output capacitors facilitate …

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  5V to 3.3V Regulator with Fail-Safe Switchover &mdash DN82
  PDF, 74 Kb, Archivo publicado: mayo 1, 1994
  Extracto del documento

  advertisement 5V to 3.3V Regulator with Fail-Safe Switchover – Design Note 82
  Mitchell Lee
  Newer microprocessors designed for replacing existing
  5V units operate from lower voltage supplies. In the past
  a processor swap was simply a matter of removing one
  IC and replacing it with an updated version. But now
  the upgrade path involves switching from a 5V chip to
  one that requires 3.xxV.
  One means of changing supply voltage from 5V to 3.xxV
  is to clip a jumper that bypasses a local 3.xxV regulator.
  This is not a good solution since it leaves too much to
  chance. Failure to remove the jumper can result in the
  instant destruction of the new microprocessor upon
  application of power. A means of automatically sensing
  the presence of a 3.xxV or 5V processor is necessary.
  Intel microprocessors include a special pin called
  “VOLDET” which can be used to determine whether
  or not a particular chip needs 3.xxV or 5V. Figure 1
  shows a simple circuit that takes advantage of this
  pin to automatically “jumper out” a 3.xxV regulator
  whenever a 5V processor is inserted into the socket. VOLDET is pulled low on 3.xx processors; it is buffered
  by transistor Q2 which grounds the gate of a bypassing
  switch (Q1). Q1 is turned off leaving the LTВ®1085 to …

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  5V to 3.3V Circuit Collection &mdash DN91
  PDF, 74 Kb, Archivo publicado: nov 1, 1994
  Extracto del documento

  advertisement 5V to 3.3V Circuit Collection – Design Note 91
  Richard Markell and Craig Varga
  High Efficiency 3.3V Regulator
  INPUT
  VOLTAGE
  5V + 6
  VIN
  7
  3 IPGM SHDN 8 3.3V Battery-Powered Supply with Shutdown
  8 3w
  22ОјF*
  25V LBIN 50μH† GND 1N5818 + 2w
  47ОјF**
  16V 4 * AVX TPSD226K025
  ** AVX TPSD476K016
  † COILTRONICS CTX50-4 OUT 1 LT1121-3.3 5V
  5 1
  VOUT
  LTC1174-3.3
  2
  5
  LBOUT
  SW IN 0.1ОјF + 1ОјF …

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Clasificación del fabricante

• Power Management > LDO Linear Regulators > Positive Linear Regulators (LDO) | Extended Temperature (H & MP) Linear Regulators

Otros nombres:

LT1129CTPBF, LT1129CT PBF