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Application Notes

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  Load Transient Response Testing for Voltage Regulators &mdash AN104
  PDF, 521 Kb, File published: Oct 1, 2006
  Semiconductor memory, card readers, microprocessors, discdrives, piezoelectric devices and digitally based systems furnishtransient loads that a voltage regulator must service. Ideally,regulator output is invariant during a load transient. In practice,some variation is encountered and becomes problematic if allowableoperating voltage tolerances are exceeded. This mandatestesting the regulator and its associated support components toverify desired performance under transient loading conditions.Various methods are employable to generate transient loads,allowing observation of regulator response. This application notepresents open and closed loop transient load testing circuitrywith measured performance taken under various conditions.Practical considerations for a memory supply voltage regulatorare reviewed. Four appended sections cover capacitor parasiticsand their effects on load transient response, output capacitor selection,probing techniques and a stabilized transient load tester.
  Extract from the document

  Application Note 104
  October 2006
  Load Transient Response Testing for Voltage Regulators
  Practical Considerations for Testing and Evaluating Results
  Jim Williams
  INTRODUCTION
  Semiconductor memory, card readers, microprocessors,
  disc drives, piezoelectric devices and digitally based systems furnish transient loads that a voltage regulator must
  service. Ideally, regulator output is invariant during a load
  transient. In practice, some variation is encountered and
  becomes problematic if allowable operating voltage tolerances are exceeded. This mandates testing the regulator
  and its associated support components to verify desired
  performance under transient loading conditions. Various
  methods are employable to generate transient loads, allowing observation of regulator response.
  Basic Load Transient Generator
  Figure 1 diagrams a conceptual load transient generator.
  The regulator under test drives DC and switched resistive
  loads, which may be variable. The switched current and output voltage are monitored, permitting comparison of
  the nominally stable output voltage versus load current
  under static and dynamic conditions. The switched current
  is either on or off; there is no controllable linear region.
  Figure 2 is a practical implementation of the load transient
  generator. The voltage regulator under test is augmented …

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  Signal Sources, Conditioners and Power Circuitry Circuits of the Fall, 2004 &mdash AN98
  PDF, 886 Kb, File published: Nov 19, 2004
  Eighteen circuits are presented in this compilation. Signal sources include a voltage controlled current source, an amplitude/frequency stabilized sine wave oscillator, a versatile, 0V to 50V wideband level shift and four sub-nanosecond pulse generators with risetimes as low as 20ps. Five signal conditioners appear; a unique, single positive rail powered amplifier with output to (and below) zero volts, a milliohmmeter, a 0.02% accurate instrumentation amplifier with 120dB CMRR at 125VCM, a 100MHz switch with 5mV control channel feedthrough and a 5V powered, 15ppm linearity quartz stabilized V→F, converter. The power circuits section features a Xenon flashlamp supply, two 5V powered, 0V to 300V DC/DC converters, a fixed 200V output circuit for APD bias, a 100W 0V to 500V, 28V powered converter and a high current paralleling scheme for linear regulators. Two appended sections consider measurement technique and connection practice in sub-nanosecond circuits.
  Extract from the document

  Application Note 98
  November 2004
  Signal Sources, Conditioners and Power Circuitry
  Circuits of the Fall, 2004
  Jim Williams
  Introduction
  Occasionally, we are tasked with designing circuitry for a
  specific purpose. The request may have customer origins
  or it may be an in-house requirement. Alternately, a circuit
  may be developed because its possibility is simply too
  attractive to ignore1. Over time, these circuits accumulate,
  encompassing a wide and useful body of proven capabilities. They also represent substantial effort. These considerations make publication an almost obligatory proposition
  and, as such, a group of circuits is presented here. This is
  not the first time we have displayed such wares and, given
  the encouraging reader response, it will not be the last2.
  Eighteen circuits are included in this latest effort, roughly
  arranged in the categories given in this publication’s title.
  They appear at the next paragraph.
  Voltage Controlled Current Source—Ground Referred
  Input and Output
  A voltage controlled current source with ground referred
  input and output is difficult to achieve. Executions exist,
  but are often cumbersome, involving numerous components. Figure 1’s conceptual design utilizes a differential …

Design Notes

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  Secondary Side Dual Output Controller Tightly Regulates Two Isolated Outputs &mdash DN1000
  PDF, 90 Kb, File published: Dec 1, 2003
  Extract from the document

  advertisement Secondary Side Dual Output Controller Tightly Regulates Two
  Isolated Outputs – Design Note 1000
  Charlie Zhao and Wei Chen
  Introduction
  Many systems with dual output isolated power supplies
  require tight regulation on both outputs. The LTВ®3804
  makes it possible to satisfy this requirement in a space
  saving and efficient circuit.
  The LT3804 is a secondary side dual output controller. It
  contains an error amplifier and an optocoupler driver to
  regulate the first output. It also includes a complete PWM
  controller and dual N-channel MOSFET drivers for the
  second output. The power to the second output is transferred directly from the transformer secondary winding
  without going through the first output stage, thus minimizing the size of the output inductor and capacitor of the
  first output. Accurate output regulation for both outputs is
  assured—even if the power supply’s outputs are far away
  from the actual loads—due to true differential remote
  sensing.
  Dual Output Isolated Power Supply
  Figure 1 shows a dual output high efficiency isolated
  DC/DC power supply with 36V to 72V input range and two
  outputs of 3.3V/15A and 1.8V/15A. The basic power stage
  topology is a 2-switch forward converter with synchronous rectification. The primary side is controlled by the …

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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
  Extract from the document

  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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  Single-Inductor, Positive-Output Buck/Boost Converter Uses No Rsense Controller &mdash LT Journal
  PDF, 136 Kb, File published: Jun 1, 1999
  Extract from the document

  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

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