Datasheet Linear Technology LT3468-2

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LT3468 LT3468-1

Application Notes

• Download
  High Voltage, Low Noise, DC/DC Converters &mdash AN118
  PDF, 2.6 Mb, File published: Mar 28, 2008
  Photomultipliers (PMT), avalanche photodiodes (APD), ultrasonic transducers, capacitance microphones, radiation detectors and similar devices require high voltage, low current bias. Additionally, the high voltage must be pristinely free of noise; well under a millivolt is a common requirement with a few hundred microvolts sometimes necessary. Normally, switching regulator configurations cannot achieve this performance level without employing special techniques. One aid to achieving low noise is that load currents rarely exceed 5mA. This freedom permits output filtering methods that are usually impractical.
  Extract from the document

  Application Note 118
  March 2008
  High Voltage, Low Noise, DC/DC Converters
  A Kilovolt with 100 Microvolts of Noise
  Jim Williams This publication describes a variety of circuits featuring
  outputs from 200V to 1000V with output noise below 100ВµV
  measured in a 100MHz bandwidth. Special techniques
  enable this performance, most notably power stages
  optimized to minimize high frequency harmonic content.
  Although sophisticated, all examples presented utilize
  standard, commercially available magnetics—no custom
  components are required. This provision is intended to
  assist the user in quickly arriving at a produceable design.
  Circuits and their descriptions are presented beginning
  with the next ink.
  BEFORE PROCEEDING ANY FURTHER, THE READER
  IS WARNED THAT CAUTION MUST BE USED IN THE
  CONSTRUCTION, TESTING AND USE OF THE TEXT’S
  CIRCUITS. HIGH VOLTAGE, LETHAL POTENTIALS ARE
  PRESENT IN THESE CIRCUITS. EXTREME CAUTION
  MUST BE USED IN WORKING WITH, AND MAKING
  CONNECTIONS TO, THESE CIRCUITS. REPEAT: THESE
  CIRCUITS CONTAIN DANGEROUS, HIGH VOLTAGE …

• Download
  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

• Download
  Basic Flashlamp Illumination Circuitry for Cellular Telephones/Cameras &mdash DN345
  PDF, 110 Kb, File published: Sep 2, 2004
  Extract from the document

  Basic Flashlamp Illumination Circuitry for
  Cellular Telephones/Cameras – Design Note 345
  Jim Williams
  Introduction
  Next generation cellular telephones will include high quality photographic capability. Flashlamp-based lighting is
  crucial for good photographic performance. A previous
  full-length Linear Technology publication detailed flash illumination issues and presented flash circuitry equipped
  with “red-eye” reduction capability.1,2 Some applications do not require this feature; deleting it results in an
  extremely simple and compact flashlamp solution.
  Flashlamp Circuitry
  Figure 1’s circuit consists of a power converter, flashlamp, storage capacitor and an SCR-based trigger. In
  operation the LTВ®3468-1 charges C1 to a regulated 300V
  at about 80% efficiency. A “trigger” input turns the SCR
  on, depositing C2’s charge into T2, producing a high
  voltage trigger event at the flashlamp. This causes the
  lamp to conduct high current from C1, resulting in an
  intense flash of light. LT3468-1 associated waveforms,
  DANGER! Lethal Potentials Present — Use Caution
  D1
  +VIN
  3V TO 6V 5 4 8 1 + C1
  13ОјF
  330V VIN D2 SW LT3468-1 GND …

Articles

• Download
  Photoflash Capacitor Chargers Fit into Tight Spots &mdash LT Journal
  PDF, 379 Kb, File published: Dec 1, 2003
  Extract from the document

  LINEAR TECHNOLOGY DECEMBER 2003 IN THIS ISSUE…
  COVER ARTICLE
  Photoflash Capacitor Chargers
  Fit into Tight Spots .1
  Albert Wu Issue Highlights .2
  LTCВ® in the News .2
  DESIGN FEATURES
  Digital Programmable Oscillator Is
  Smaller, Sturdier and More Versatile
  than Crystal Oscillators .7
  Albert Huntington Hot Swapв„ў Controller with PowerUp Timeout Function Simplifies Hot
  Swapping Boards with Multiple
  Power Supplies .10
  Anthony Ng and YK Sim Low Voltage Wizardry Provides the
  Ultimate Power-On Reset Circuit .14
  Bob Jurgilewicz New Power for Ethernet—
  Disconnect and Clean Up
  (Epilogue to a 3-part series) .17
  Jacob Herbold Save Board Space with a High
  Efficiency Dual Synchronous,
  600mA, 1.5MHz Step-Down
  DC/DC Regulator.19
  Damon Lee White LED Driver Minimizes Space, …

Model Line

Manufacturer's Classification

• Power Management > Switching Regulator > Xenon Photoflash Charger