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  Active Voltage Positioning Reduces Output Capacitors &mdash Design Solutions 10
  PDF, 130 Kb, File published: Nov 1, 1999
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  Design Solutions 10
  November 1999
  Active Voltage Positioning Reduces Output Capacitors
  by Robert Sheehan
  INTRODUCTION
  Power supply performance, especially transient response,
  is key to meeting today’s demands for low voltage, high
  current microprocessor power. In an effort to minimize
  the voltage deviation during a load step, a technique that
  has recently been coined “active voltage positioning” is
  generating substantial interest and gaining popularity in
  the portable computer market. The benefits include lower
  peak-to-peak output voltage deviation for a given load
  step, without having to increase the output filter capacitance. Alternatively, the output filter capacitance can be
  reduced while maintaining the same peak-to-peak transient response.
  BASIC PRINCIPLE
  The term “active voltage positioning” (AVP) refers to
  setting the power supply output voltage at a point that is
  dependent on the load current. At minimum load, the
  output voltage is set to a slightly higher than nominal level.
  At full load, the output voltage is set to a slightly lower than
  nominal level. Effectively, the DC load regulation is
  degraded, but the load transient voltage deviation will be …

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  2-Step Power Conversion: Portable Power for the Future &mdash Design Solutions 8
  PDF, 119 Kb, File published: Apr 1, 1999
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  Design Solutions 8
  April 1999
  2-Step Power Conversion:
  Portable Power for the Future
  As microprocessor operating voltages continue to
  decrease, power conversion for CPU core power is
  becoming a daunting challenge. A core power supply
  must have fast transient response, good efficiency, and
  low heat generation in the vicinity of the processor. These
  factors will soon force a move away from 1-step power
  conversion from battery or wall adapter to processor, to
  2-step conversion where the CPU core power is obtained
  from the 5V supply. While new to the portable arena,
  distributed power systems using 5V as a bus voltage have
  been used in large systems for many years. And although
  it may not be absolutely necessary to adopt this architecture in portables today, the clock is ticking for the old
  brute-force approach.
  Let’s start with the biggest argument against 2-step
  conversion: the perceived drop in efficiency and attendant heat generation in the 5V supply. Quick calculations may give a false impression that efficiency significantly
  decreases. It does not! Later in this paper we will show
  accurate calculations of efficiency for 2-step power conversion based on actual demo board measurements that
  show overall efficiency numbers equal to 1-step high
  efficiency converters. …

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  2-Phase DC/DC Controller Reduces Capacitanceand Increases Battery Life in Portable Applications &mdash Design Solutions 9
  PDF, 106 Kb, File published: Jun 1, 1999
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  Design Solutions 9
  June 1999
  2-Phase DC/DC Controller Reduces Capacitance
  and Increases Battery Life in Portable Applications
  The LTCВ®1628 dual high efficiency DC/DC controller brings
  the considerable benefits of 2-phase operation to portable
  applications for the first time. Notebook computers, PDAs,
  handheld terminals and automotive electronics will all
  benefit from the lower input filtering requirement, reduced
  electromagnetic interference (EMI) and increased efficiency associated with 2-phase operation. coming from the switches, greatly reducing the overlap
  time where they add together (see Figure 1). The result is
  a significant reduction in total RMS input current, which,
  in turn, allows less expensive input capacitors to be used,
  reduces shielding requirements for EMI and improves real
  world operating efficiency.
  Figure 2 compares the input waveforms for a representative 1-phase dual switching regulator to the new LTC1628
  2-phase dual switching regulator. An actual measurement
  of the RMS input current under these conditions shows
  that 2-phase operation lowers the input current from
  2.53ARMS to 1.55ARMS. Why the need for 2-phase operation? Before the LTC1628,
  constant-frequency dual switching regulators operated
  both channels in phase (i.e., 1-phase operation). This
  means that both switches turned on at the same time, …

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  LTC1702/LTC1703 Switching Regulator Controllers Set a New Standard for Transient Response &mdash DN206
  PDF, 87 Kb, File published: May 2, 1999
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  advertisement LTC1702/LTC1703 Switching Regulator Controllers Set a New
  Standard for Transient Response – Design Note 206
  Dave Dwelley
  The LTC В®1702 is the п¬Ѓrst in a new family of low voltage, high speed switching regulator controllers. It is
  designed to operate from a standard 5V logic supply
  and generate two lower voltage, high current regulated
  outputs. Running at a п¬Ѓxed 550kHz switching frequency,
  each side of the LTC1702 features a voltage feedback
  architecture with a 25MHz gain-bandwidth op amp as the
  feedback amplifier, allowing loop crossover frequencies
  in excess of 50kHz. Powerful onboard MOSFET drivers
  allow the LTC1702 to drive large, high current external
  MOSFETs efficiently at 550kHz. The high feedback loop
  bandwidth maintains excellent transient response, and
  the high switching frequency allows the use of small
  external inductors and capacitors even as load currents
  rise beyond 10A. The dual output LTC1702 is packaged
  in a space-saving 24-pin narrow SSOP. consists of a modified LTC1702 with an internal 5-bit DAC
  controlling the output voltage on side 1. The DAC conforms to the Intel Mobile VID specifications.
  The LTC1702/LTC1703 each consist of two independent
  switching regulator controllers in one package. Each
  controller is designed to be wired as a voltage feedback,
  synchronous step-down regulator, using two external …

Articles

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  Active Voltage Positioning Saves Output Capacitors in Portable Computer Applications &mdash LT Journal
  PDF, 169 Kb, File published: Feb 1, 2000
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  DESIGN IDEAS Active Voltage Positioning Saves
  Output Capacitors in Portable by John Seago
  and Ajmal Godil
  Computer Applications
  Introduction
  pp. 16–20) can take advantage of
  active voltage positioning. Active voltage positioning is a technique that can be used to save cost
  and space by reducing the number of
  output capacitors required to meet a
  microprocessor’s power supply
  requirements. Total system cost and
  required PCB space are important
  aspects of today’s portable equipment
  designs, so decreasing the number of
  large, expensive output capacitors is
  worth some effort. Both the LTC1735/
  LTC1736 current mode switching
  regulator controllers (Linear Technology IX:1, February 1999, pp. 1, 3–5,
  35) and the LTC1702/LTC1703
  voltage mode controllers (Linear Technology IX:3, September 1999, Microprocessor Load Steps
  Microprocessors frequently change
  their load current requirement from
  almost no load to maximum load current and back again very quickly. The …

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  LTC1702/LTC1703 Switching Regulator Controllers Set a New Standard for Transient Response &mdash LT Journal
  PDF, 192 Kb, File published: Sep 1, 1999
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  DESIGN FEATURES LTC1702/LTC1703 Switching Regulator
  Controllers Set a New Standard for
  Transient Response
  by Dave Dwelley
  Introduction
  The LTC1702 dual switching regulator controller uses a high switching
  frequency and precision feedback circuitry to provide exceptional output
  regulation and transient response
  performance. Running at a fixed
  550kHz switching frequency, each
  side of the LTC1702 features a voltage feedback architecture using a
  25MHz gain-bandwidth op amp as
  the feedback amplifier, allowing loopcrossover frequencies in excess of
  50kHz. Large onboard MOSFET drivers allow the LTC1702 to drive high
  current external MOSFETs efficiently
  at 550kHz and beyond. The high
  switching frequency allows the use of
  small external inductors and capacitors while maintaining excellent
  output ripple and transient response,
  even as load currents exceed the 10A
  level. The dual-output LTC1702 is
  packaged in a space-saving 24-pin
  narrow SSOP, minimizing board space …

Model Line

Manufacturer's Classification

• Power Management > Switching Regulator > Digitally Programmable Regulators

Other Names:

LTC1703IGPBF, LTC1703IG PBF