Datasheet Linear Technology LT1777IS#PBF

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Design Notes

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  LT1777 High Voltage, Low Noise Buck Switching Regulator &mdash DN212
  PDF, 115 Kb, File published: Sep 2, 1999
  Extract from the document

  advertisement LT1777 High Voltage, Low Noise Buck Switching Regulator
  Design Note 212
  Ajmal Godil
  The LTВ®1777 is a wide input range buck (step-down)
  switching regulator specially designed for low noise applications. The LT1777 can be beneficial in applications
  where low noise is critical, such as telecom, automotive
  cellular and GPS receiver power supplies. The schematic
  in Figure 1 highlights the capabilities of the LT1777. VSW NODE
  VOLTAGE
  10V/DIV SWITCH
  CURRENT
  200mA/DIV The LT1777 can accept input voltages from 7.4V to 48V
  and has a nominal switching frequency of 100kHz. The
  monolithic die includes an onboard 700mA peak current
  switch, oscillator, control and protection circuitry. It uses
  current mode control that delivers excellent dynamic
  input supply rejection and short-circuit protection. In
  order to achieve low noise, the LT1777 is equipped with
  dI/dt limiting circuitry that is programmed via a small
  inductor (LSENSE in Figure 1) in the power path. It also
  contains internal circuitry to limit dV/dt during switch
  turn-on and turn-off.
  Figure 2 shows the VSW node voltage and switch current …

Articles

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  Generating Low Cost, Low Noise, Dual-Voltage Supplies &mdash LT Journal
  PDF, 72 Kb, File published: Feb 1, 1999
  Extract from the document

  DESIGN IDEAS Generating Low Cost, Low Noise,
  Dual-Voltage Supplies
  by Ajmal Godil
  Some sensitive electronic applications, such as telecommunication and
  data acquisition, require both 5V and
  –5V low noise supplies, which may
  have to be generated from a single
  high voltage positive supply. The circuit in Figure 1 shows a cost-effective
  way to generate 5V and –5V from a
  single 10V–28V supply by using the
  low noise LT1777 and a few off-theshelf components.
  The LT1777 is a step-down regulator specially designed for low noise
  applications. In order to achieve low
  VIN
  10V–28V
  4
  10
  3 SHDN 14
  100pF VCC VSW VIN VD SHDN
  VC FB
  LT1777 GND
  GND 12
  R3 …

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Manufacturer's Classification

• Power Management > Switching Regulator > Step-Down (Buck) Regulators > High Input Voltage Buck | Internal Power Switch Buck
• Power Management > Switching Regulator > Ultralow Noise Regulators

Other Names:

LT1777ISPBF, LT1777IS PBF