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LT3420-1

Design Notes

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  Photoflash Capacitor Charger Has Fast Efficient Charging and Low-Battery Drain &mdash DN303
  PDF, 106 Kb, File published: Feb 1, 2003
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  Photoflash Capacitor Charger Has Fast Efficient Charging
  and Low Battery Drain – Design Note 303
  Albert Wu
  Figure 1a shows a typical LT3420 circuit that can charge
  a 220μF photoflash capacitor to 320V in 3.5 seconds
  from a 5V input. Figure 1b shows the charge time as a
  function of battery voltage. In Figure 1a, the circuitry to
  the right of C4 shows a typical method to generate the
  light pulse once the photoflash capacitor is charged.
  When the SCR is fired, the flying lead along the glass
  envelope of the Xenon bulb reaches many kilovolts in
  potential. This ionizes the gas inside the bulb forming a
  low impedance path across the bulb. The energy stored
  in the photoflash capacitor quickly flows through the
  Xenon bulb, producing the burst of light needed for
  flash photography. Introduction
  The LT®3420 is designed to charge large-valued capacitors—such as those used for the strobe flashes
  of digital and film cameras—to high voltages. These
  photoflash, or strobe, capacitors range in value from
  a hundred microfarads to over a millifarad, with target
  output voltages above 300V. Traditional strobe capacitor charging methods are either inefficient or require
  software overhead. The LT3420 provides a compact,
  simple to use and efп¬Ѓcient charger solution that requires no software, saving space, battery life, design …

Articles

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  LT3420 Charges Photoflash Capacitors Quickly and Efficiently While Using Minimal Board Space &mdash LT Journal
  PDF, 105 Kb, File published: May 1, 2002
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  DESIGN FEATURES LT3420 Charges Photoflash Capacitors
  Quickly and Efficiently While Using
  by Albert Wu
  Minimal Board Space
  Introduction VOUT
  50V/DIV VCHARGE
  5V/DIV
  VBAT = 5V 1s/DIV 3420 F01b Figure 1b. Charging waveform Linear Technology Magazine May 2002 DANGER HIGH VOLTAGE
  OPERATION BY HIGH VOLTAGE
  TRAINED PERSONNEL ONLY
  VBAT
  1.8V TO 10V
  C1
  4.7ВµF T1
  1:12
  5,6 3,4 320V 8 D1 FLYING
  LEAD 1 R1
  51.1k
  VBAT
  VCC
  2.5V TO 10V CHARGE
  DONE C2
  4.7ВµF RFB VCC SW …

Model Line

Manufacturer's Classification

• Power Management > Switching Regulator > Xenon Photoflash Charger

Other Names:

LT3420EMSPBF, LT3420EMS PBF