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Application Notes

• Download
  Power Conversion, Measurement and Pulse Circuits &mdash AN113
  PDF, 692 Kb, File published: Aug 7, 2007
  This ink marks LTC’s eighth circuit collection publication.1 We are continually surprised, to the point of near mystification, by these circuit amalgams seemingly limitless appeal. Reader requests ascend rapidly upon publication, remaining high for years, even decades. All LTC circuit collections, despite diverse content, share this popularity, although just why remains an open question. Why is it? Perhaps the form; compact, complete, succinct and insular. Perhaps the freedom of selection without commitment, akin to window shopping. Or, perhaps, simply the pleasure of new recruits for the circuit aficionados intellectual palate. Locally based electrosociolgists, spinning elegantly contrived theories, offer explanation, but no convincing evidence is at hand. What is certain is that readers are attracted to these compendiums and that calls us to attention. As such, in accordance with our mission to serve customer preferences, this latest collection is presented. Enjoy.
  Extract from the document

  Application Note 113
  August 2007
  Power Conversion, Measurement and Pulse Circuits
  Tales From the Laboratory Notebook, 2005-2007
  Jim Williams
  INTRODUCTION
  This ink marks LTC’s eighth circuit collection publication.1
  We are continually surprised, to the point of near mystification, by these circuit amalgams seemingly limitless
  appeal. Reader requests ascend rapidly upon publication,
  remaining high for years, even decades. All LTC circuit
  collections, despite diverse content, share this popularity, although just why remains an open question. Why is
  it? Perhaps the form; compact, complete, succinct and
  insular. Perhaps the freedom of selection without commitment, akin to window shopping. Or, perhaps, simply
  the pleasure of new recruits for the circuit aficionados
  intellectual palate. Locally based electrosociolgists, spinning elegantly contrived theories, offer explanation, but
  no convincing evidence is at hand. What is certain is that
  readers are attracted to these compendiums and that calls
  us to attention. As such, in accordance with our mission
  to serve customer preferences, this latest collection is
  presented. Enjoy. all with outputs below 600mV, are typical power sources
  for such a converter.
  Figure 1, an N-channel JFET I-V plot, shows drain-source
  conduction under zero bias (gate and source tied together) …

• Download
  A Monolithic Switching Regulator with 100ВµV Output Noise &mdash AN70
  PDF, 1.7 Mb, Language: en, File published: Oct 1, 1997
  This publication details circuitry and applications considerations for the LT1533 low noise switching regulator. Eleven DC/DC converter circuits are presented, some offering <100µV output noise in a 100MHz bandwidth. Tutorial sections detail low noise DC/DC design, measurement, probing and layout techniques, and magnetics selection.
  Extract from the document

  Application Note 70
  October 1997
  A Monolithic Switching Regulator with 100ВµV Output Noise
  “Silence is the perfectest herald of joy .”
  Jim Williams INTRODUCTION
  Size, output flexibility and efficiency advantages have
  made switching regulators common in electronic apparatus. The continued emphasis on these attributes has
  resulted in circuitry with 95% efficiency that requires
  minimal board area. Although these advantages are welcome, they necessitate compromising other parameters. back to the driving source (“reflected” noise) and it is
  radiated. The multiple transmission paths combine with
  the high frequency content to make noise suppression
  difficult. Unconscionable amounts of bypass capacitors,
  ferrite beads, shields, Mu-metal and aspirin have been
  expended in attempts to ameliorate noise-induced effects. Switching Regulator “Noise”
  Something commonly referred to as “noise” is a primary
  concern. The switched mode power delivery that permits
  the aforementioned advantages also creates wideband
  harmonic energy. This undesirable energy appears as
  radiated and conducted components commonly labeled
  as “noise.” Actually, switching regulator output “noise” is
  not really noise at all, but coherent, high frequency residue
  directly related to the regulatorвЂ^TMs switching.1 Figure 1
  shows typical switching regulator output noise. Two distinct characteristics are present. The slow, ramping output …

Design Notes

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  Ultralow Power Comparators Include Reference &mdash DN123
  PDF, 83 Kb, File published: Feb 2, 1996
  Extract from the document

  Ultralow Power Comparators Include Reference
  Design Note 123
  Robert Reay
  With the explosion of battery-powered products has
  come the need for circuits that draw as little supply
  current as possible in order to extend battery life. Linear
  Technology’s new family of micropower comparators
  with built-in references is designed to meet that need.
  Drawing only 1ОјA of supply current per comparator, the
  LTC ®1440–LTC1445 family provides the perfect solution to battery-powered system monitoring problems. 7
  3 IN+ +
  8 4 IN – OUT – 5 HYST
  6 REF
  2.4M
  5% The LTC1440–LTC1445 family features 1μA comparators, adjustable hysteresis, TTL/CMOS outputs that sink
  and source current and a 1ОјA reference that can drive
  a bypass capacitor of up to 0.01ОјF without oscillation.
  The parts operate from a 2V to 11V single supply or a
  ±1V to ±5V dual supply. Each comparator’s input voltage
  range swings from the negative supply rail to within
  1.3V of the positive supply. The comparator propagation
  delay is 12Ојs with a 10mV overdrive, and the supply
  current glitches that commonly occur when comparators change logic states have been eliminated. Table 1 …

• Download
  New Comparators Feature Micropower Operation Under All Conditions &mdash DN137
  PDF, 443 Kb, File published: Sep 2, 1996
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  New Comparators Feature Micropower Operation
  Under All Conditions – Design Note 137
  Jim Williams
  Some micropower comparators have operating modes
  that allow excessive current drain. In particular, poorly
  designed devices can conduct large transient currents
  during switching. Such behavior causes dramatically
  increased power drain with rising frequency, or when
  the inputs are nearly balanced, as in battery monitoring
  applications. resulting in greatly reduced power consumption versus
  frequency, or when the inputs are nearly balanced. Figure 2’s
  plot contrasts the LTC1440’s power consumption versus
  frequency with that of another comparator specified as a
  micropower component. The LTC1440 has about 200 times
  lower current consumption at higher frequencies, while
  maintaining a significant advantage below 1kHz. Figure 1 shows a popular micropower comparator’s current
  consumption during switching. Trace A is the input pulse,
  trace B is the output response and trace C is the supply
  current. The device, specified for micropower level supply drain, pulls 40mA during switching. This undesirable
  surprise can upset a design’s power budget or interfere
  with associated circuitry’s operation. Table 1 shows some LTC1440 family characteristics. A voltage reference and programmable hysteresis are included
  in some versions, with 5Вµs response time for all devices. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks
  of Linear Technology Corporation. All other trademarks are the property of their …

• Download
  Ultralow Quiescent Current DC/DC Converters for Light Load Applications &mdash DN142
  PDF, 84 Kb, File published: Nov 1, 1996
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  Ultralow Quiescent Current DC/DC Converters for
  Light Load Applications – Design Note 142
  Sam Nork 2-Cell to 5V Conversion with IQ = 12ОјA
  The circuit in Figure 1 produces a regulated 5V output
  from a 2V to 5V input and consumes only 12ОјA (typical) of supply current. The LTCВ®1516 is a charge pump
  DC/DC converter that uses Burst ModeВ® operation to
  provide a regulated 5V output.
  This circuit achieves ultralow quiescent current by
  disabling the internal charge pump when the output is
  in regulation. The charge pump is enabled only when
  the output load forces the voltage on COUT to droop by
  approximately 80mV. External capacitors C1 and C2
  are then used to transfer charge from VIN to VOUT until
  the output climbs back into regulation. This regulation
  method results in approximately 100mV of voltage
  ripple at the output. VIN = 2V TO 5V 2 + 10ОјF 3 + 10ОјF 4 The low quiescent current of the LTC1516 may render
  shutdown of the 5V supply unnecessary because the
  12ОјA quiescent current is lower than the self-discharge
  rate of many batteries. However, the part is also equipped
  with a 1ОјA shutdown mode for additional power savings.
  Ultralow Quiescent Current (IQ < 5ОјA)
  Regulated Supply
  The LTC1516 contains an internal resistor divider that …

• Download
  The Smart Rock &mdash DN161
  PDF, 322 Kb, File published: Aug 1, 1997
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  The “Smart Rock”: A Micropower Transponder
  Design Note 161 Dale Eager
  INTRODUCTION
  A “smart rock” is a locating device that is buried at a specific
  site. It is interrogated by a portable source and responds
  with information about its position, identification number
  or any data that it has collected since its last interrogation.
  Ideally, a smart rock, once placed, will wait, listening for
  its interrogator, for many years, or even for decades. A
  smart rock buried on a nature trail might send its identification number to a traveler’s handheld transponder, which
  would decode the identification number and play a message
  describing the surrounding sights. It could also be used
  to direct the traveler which way to turn at a trail junction.
  Smart rocks are sometimes placed along the edges of
  cliffs so that interrogators built into vehicles, such as
  bulldozers, will cause them to stop before they get too
  close to the edge.
  THE MICROPOWER SUBCIRCUITS
  The Oscillator
  Figure 1 shows the LTC В® 1440 implementing a micropower
  oscillator. This circuit provides the references for both
  voltage and frequency needed in our rock; it draws only
  a few microamps of battery current. …

• Download
  1ВµA Op Amp Permits Precision Portable Circuitry &mdash DN163
  PDF, 78 Kb, File published: Sep 2, 1997
  Extract from the document

  1µA Op Amp Permits Precision Portable Circuitry – Design Note 163
  Mitchell Lee and Jim Williams
  The circuit’s internal AC coupling prevents A1’s DC characteristics from influencing overall DC performance,
  accounting for the extremely low offset errors noted. A new dual op amp with only 1μA power consumption and precision DC specifications permits high
  performance portable applications. The LT В®1495
  has 375ОјV offset, 2ОјV/В°C drift, 1nA bias current and
  100dB of open-loop gain. These attributes, combined
  with careful design, make portable, high performance
  circuitry possible. The desired micropower operation and A1’s bandwidth
  dictate the 5Hz clock rate. As such, resultant overall
  bandwidth is low. Full power bandwidth is 0.05Hz with
  a slew rate of about 1V/s. Clock related noise, about
  5μV, can be reduced by increasing CCOMP, with commensurate bandwidth reduction. 5.5μA, 0.05μV/°C Chopped Amplifier
  Figure 1 shows a chopped amplifier requiring only 5.5μA
  supply current. Offset voltage is 5ОјV, with 0.05ОјV/В°C
  drift. Gain exceeding 108 affords high accuracy, even
  at large closed-loop gains. 0.03% Linear V/F Converter with 13ОјA Power Drain
  Figure 2’s voltage-to-frequency converter takes full
  advantage of the LT1495’s low power consumption.
  A 0V to 2.5V input produces a 0Hz to 10kHz output,
  with 0.03% linearity, 250ppm/В°C drift and 10ppm/V
  supply rejection. Maximum current consumption is
  only 13ОјA, 200 times lower than currently available ICs. …

Articles

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  Comparator Circuit Provides Automatic Shutdown of the LT1795 High Speed ADSL Power Amplifier &mdash LT Journal
  PDF, 154 Kb, File published: Sep 1, 1999
  Extract from the document

  DESIGN IDEAS Comparator Circuit Provides Automatic
  Shutdown of the LT1795 High Speed
  ADSL Power Amplifier
  by Tim Regan
  Introduction
  Data transmission standards such
  as HDSL2, ADSL (both Full Rate and
  G.Lite) and VDSL (collectively known
  as xDSL) require the combined speed,
  output power and dynamic range
  capabilities of the LT1795 to drive the
  telephone line. In a typical data communications installation, in both the
  telephone central office and office
  building sites, hundreds of telephonewire pairs are brought together into a
  line multiplexer. These multiplexers
  compact the individual line driver and
  receiver circuits to save space. Eight
  lines per PC card are often implemented. This tight partitioning raises
  the challenges of both power and heat
  management in each installation.
  A simple comparator circuit can be
  used to monitor the activity of an
  individual phone line and completely …

Model Line

Manufacturer's Classification

• Signal Conditioning > Comparators > Micropower Comparators | Application Specific Comparators
• Signal Conditioning > Voltage References > Reference Plus Comparator or Amplifier