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Application Notes

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  Power Conditioning for Notebook and Palmtop Systems &mdash AN51
  PDF, 260 Kb, File published: Aug 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.
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  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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  Micropower High Side MOSFET Drivers &mdash AN53
  PDF, 226 Kb, File published: Jan 3, 1993
  This application note describes the operation of high-side Nchannel MOSFET switch drivers designed specifically for operation in battery-powered equipment, such as notebook and palmtop computers and portable medical instruments. A selection guide simplifies the proper choice of MOSFET and driver for a particular high-side switch application. Circuits to drive and protect load impedances ranging from large inductors to large capacitors are described and a section on surface mount and copper clad shunts is included.
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  Application Note 53
  January 1993
  Micropower High Side MOSFET Drivers
  Tim Skovmand
  Portable electronic equipment, such as notebook and
  palmtop computers, portable medical instruments and
  battery powered tools, are increasingly dependent upon
  efficient power management to meet the challenge of
  extracting more useful energy (time) from less battery
  volume and weight.
  One link in the power management chain which has
  received increasing scrutiny, as power supply efficiencies
  soar above 90%, is the logic controlled power switch.
  Large sections of a typical notebook computer system, for
  example, are powered via topside or “high side” MOSFET
  switches. These switches can become significant sources
  of power loss if not properly designed.
  At first glance, P-channel MOSFETs appear to be the
  natural choice for high side switching. Unfortunately, the
  RDS(ON) exhibited by most P-channels is prohibitively
  high. (Mother Nature has decreed that electron mobility
  shall exceed hole mobility in silicon by about 2.5 times, so
  that a P-channel MOSFET with the same RDS(ON) and …

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  Linear Technology Magazine Circuit Collection, Volume II &mdash AN66
  PDF, 1.1 Mb, File published: Aug 1, 1996
  Application Note 66 is a compendium of "power circuits" from the first five years of Linear Technology. This application note contains circuits that can power most any system you can imagine, from desktop computer systems to micropower systems for portable and handheld equipment. Also included here are circuits that provide 300W or more of power factor corrected DC from a universal input. Battery chargers are included, some that charge several battery types, some that are optimized to charge a single type. MOSFET drivers, high side switches and H-bridge driver circuits are also included, as is an article on simple thermal analysis.
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  Application Note 66
  August 1996 Linear Technology Magazine Circuit Collection, Volume II
  Power Products
  Richard Markell, Editor
  INTRODUCTION
  Application Note 66 is a compendium of “power circuits”
  from the first five years of Linear Technology. The objective
  is to collect the useful circuits from the magazine into
  several applications notes (another, AN67, will collect
  signal processing circuits into one Application Note) so
  that valuable “gems” will not be lost. This Application Note
  contains circuits that can power most any system you can
  imagine, from desktop computer systems to micropower
  systems for portable and handheld equipment. Also included here are circuits that provide 300W or more of
  power factor corrected DC from a universal input. Battery
  chargers are included, some that charge several battery
  types, some that are optimized to charge a single type.
  MOSFET drivers, high side switches and H-bridge driver
  circuits are also included, as is an article on simple thermal
  analysis. With these introductory remarks, I’ll stand aside
  and let the authors describe their circuits. ARTICLE INDEX
  REGULATORS—SWITCHING (BUCK)
  High Power (>4A) …

Design Notes

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  Regulator Circuit Generates Both 3.3V and 5V Outputs from 3.3V or 5V to Run Computers and RS232 &mdash DN71
  PDF, 89 Kb, File published: Jun 1, 1993
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  advertisement Regulator Circuit Generates Both 3.3V and 5V Outputs from
  3.3V or 5V to Run Computers and RS232 – Design Note 71
  David Dinsmore and Richard Markell
  Many portable microprocessor-based systems use a
  mix of 3.3V and 5V circuits. Some are still using only
  5V and inevitably some systems will end up being
  solely 3.3V based. If accessories are to be plugged
  into, or connected to any of these systems, a voltage
  conversion/power generation problem presents itself.
  The circuit shown in Figure 1 addresses the situation
  where either 5V or 3.3V power is available from the
  bus, but the accessory needs both 5V and 3.3V power. above the supply voltage and efficiently turns on and
  off the appropriate MOSFETs.
  IC2 also forms a flying capacitor buck/boost DC/DC
  converter circuit. This topology is used so that no
  transformers are necessary. Q1 is used to control this
  section’s voltage (V1). When VIN is at 5V, Q1 is off, forcing this section to operate as a step-down converter.
  It produces 3.3V which is sent to the 3.3V output of
  the circuit through IC4B. In this state, 5V power is sent
  directly through IC3A while IC3B and IC4A are off. The circuit consists of two sections, one being a DC/DC
  converter and the other being a pair of dual N-channel
  MOSFETs and their associated high side drivers that
  effectively form a DPDT switch. When VIN is at 3.3V, IC1 turns on Q1 shorting out the …

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  PC Card Power Management Techniques &mdash DN76
  PDF, 77 Kb, File published: Nov 1, 1993
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  PC Card Power Management Techniques – Design Note 76
  Tim Skovmand
  Most portable computers have sockets built in to accept
  small PC cards for use as extended memories, data/fax
  modems, network interfaces, wireless communicators,
  etc. The Personal Computer Memory Card International
  Association (PCMCIA) has released specifications, 1.0
  and 2.0, which outline the general voltage and power
  requirements for these cards.
  Power is provided by the host computer to the PC card
  through the card socket via the main VCC supply pin(s)
  and the VPP programming supply pins. Both supplies
  can be switched to different voltages to accommodate
  a wide range of card types and applications.
  The VCC supply can be switched from 5V to 3.3V and
  must be capable of supplying upwards of 1A for short
  periods of time and hundreds of milliamps continuously. Three low resistance MOSFET switches are typically used to select the card VCC power as shown in
  Figure 1. The LTC В®1165 inverting triple MOSFET driver
  accepts active-low logic commands directly from a
  common PCMCIA controller and generates gate drive
  voltages above the positive rail to fully enhance low
  5V RDS(ON) N-channel MOSFET switches. Two back-to-back
  MOSFET switches, Q2 and Q3, isolate the parasitic …

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Manufacturer's Classification

• Monitor, Control and Protection > High Side Switches & MOSFET Drivers