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Application Notes

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  Modeling and Loop Compensation Design of Switching Mode Power Supplies &mdash AN149
  PDF, 1.4 Mb, File published: Mar 23, 2015
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  Application Note 149
  January 2015
  Modeling and Loop Compensation Design of
  Switching Mode Power Supplies
  Henry J. Zhang
  Introduction Identifying The Problem Today’s electronic systems are becoming more and more
  complex, with an increasing number of power rails and
  supplies. To achieve optimum power solution density,
  reliability and cost, often system designers need to design
  their own power solutions, instead of just using commercial power supply bricks. Designing and optimizing high
  performance switching mode power supplies is becoming
  a more frequent and challenging task. A well-designed switching mode power supply (SMPS)
  must be quiet, both electrically and acoustically. An undercompensated system may result in unstable operations.
  Typical symptoms of an unstable power supply include:
  audible noise from the magnetic components or ceramic
  capacitors, jittering in the switching waveforms, oscillation
  of output voltage, overheating of power FETs and so on. Power supply loop compensation design is usually
  viewed as a difficult task, especially for inexperienced
  supply designers. Practical compensation design typically
  involves numerous iterations on the value adjustment
  of the compensation components. This is not only time
  consuming, but is also inaccurate in a complicated
  system whose supply bandwidth and stability margin …

Design Notes

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  Dual Controller Provides 2Ојs Step Response and 92% Efficiency for 1.5V Rails &mdash DN505
  PDF, 111 Kb, File published: Apr 3, 2012
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  Dual Controller Provides 2Вµs Step Response and 92% Efficiency
  for 1.5V Rails
  Design Note 505
  Mike Shriver
  Introduction
  The LTCВ®3838 is a dual output, dual phase buck controller
  that employs a controlled constant on-time, valley current
  mode architecture to provide fast load step response,
  high switching frequency and low duty cycle capability.
  The switching frequency range is 200kHz to 2MHz—its
  phase-locked loop keeps the frequency constant during
  steady-state operation and can be synchronized to an
  external clock. The LTC3838 accepts a wide input range,
  4.5V to 38V, and can produce 0.6V to 5.5V outputs.
  VIN
  4.5V TO 14V + CIN1
  180ОјF CIN2
  22ОјF
  w4 The remotely sensed VOUT1 has a voltage regulation accuracy of 0.67%, from 0В°C to 85В°C, even with a voltage
  difference of В±0.5V between local ground and remote
  ground. The current sense comparators are designed to
  sense the inductor current with either a sense resistor
  for high accuracy or with the inductor DCR directly for …

Articles

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  2MHz Dual DC/DC Controller Halves Settling Time of Load Release Transients, Features 0.67% Differential VOUT Accuracy and Is Primed for High Step-Down Ratios &mdash LT Journal
  PDF, 2.7 Mb, File published: Apr 24, 2012
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  design features 2MHz Dual DC/DC Controller Halves Settling Time of
  Load Release Transients, Features 0.67% Differential VOUT
  Accuracy and IsВ Primed for High Step-Down Ratios
  Shuo Chen and Terry Groom Electrical conditions once considered extreme are now
  the norm. Modern electronic systems demand high
  currents and very low voltages that can appear to a
  DC/DC converter as an intermittent electrical short. It is
  not uncommon for sub-0.9V power supply rails to demand
  25A or more. In this environment, tight total differential
  regulation accuracy is critical to achieve the demanding
  voltage tolerances required to power core processors
  and large ASICs. In addition, PCB and component
  size constraints have driven up converter operating
  frequencies to enable the use of smaller components. VIN
  4.5V TO 38V + CIN1
  100ВµF CIN2
  10ВµF
  Г—3 LTspice IV circuits.linear.com/546
  VIN 0.1ВµF
  3.57k + COUT2
  330ВµF
  ×2 SENSE1– SENSE2– SENSE1+ SENSE2+ BOOST1 BOOST2 0.1µF TG1 MT1 3.57k TG2 MT2
  DB2 SW1 1ВµF 15k 0.1ВµF DB1 …

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  Dual, Fast, Step-Down Controller's External Reference Input Enables Dynamic Voltage Scaling from 0.4V to 5.5V and 0.3% Total Combined Regulation Accuracy &mdash LT Journal
  PDF, 2.8 Mb, File published: Apr 10, 2013
  Extract from the document

  design features Dual, Fast, Step-Down Controller’s External Reference Input
  Enables Dynamic Voltage Scaling from 0.4V to 5.5V and
  0.3% Total Combined Regulation Accuracy
  Shuo Chen and Terry Groom Low voltage, high current
  systems require accurate
  differential regulation. It is
  not uncommon for power
  supply rails at or below
  0.9V to demand 25A or
  more, with fast transients
  that look like intermittent
  electrical shorts to the
  power supply rail. Such
  systems typically require
  power supply regulation
  accuracy of less than 1%
  regulated DC and 3% in the
  face of input transients.
  Increasingly, core processors and other
  large scale digital ICs (such as ASICs and
  FPGAs) require dynamic voltage scaling—either multiple fixed levels, or a
  continuously adjusted reference voltage
  using a servo loop—to deliver power …

Model Line

Manufacturer's Classification

• Power Management > Switching Regulator > Step-Down (Buck) Regulators > Multiple Output Buck | External Power Switch Buck Controllers

Other Names:

LTC3838IUHFPBF, LTC3838IUHF PBF