Datasheet Linear Technology LTC1540

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Design Notes

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  Op Amp, Comparator and Reference IC Provides Micropower Monitoring Capability &mdash DN190
  PDF, 72 Kb, File published: Sep 5, 1998
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  Op Amp, Comparator and Reference IC Provides Micropower
  Monitoring Capability – Design Note 190
  Jim Williams
  Introduction
  The LTC ®1541 combines a micropower amplifier,
  comparator and 1.2V reference in an 8-pin package.
  The part operates from a single 2.5V to 12.6V supply
  with typical supply current of 5ОјA. Both op amp and
  comparator feature a common mode input voltage
  range that extends from the negative supply to within
  1.3V of the positive supply. The op amp output stage
  swings from rail-to-rail. Figure 1 lists additional features
  along with a block diagram of the device. The part’s
  attributes suggest low power monitoring applications
  and two such circuits are presented here.
  Pilot Light Flame Detector with Low-Battery Lockout
  Figure 2 shows a pilot light flame detector with low-battery
  lockout. The amplifier (“A”), running open loop, compares
  a small portion of the reference with the thermocouple-generated voltage. When the thermocouple is hot, the
  amplifier’s output swings high, biasing Q1 on. Hysteresis,
  provided by the 10M resistor, ensures clean transitions,
  while the diodes clamp static generated voltages to the
  rails. The 100k–2.2ОјF RC п¬Ѓlters the signal to the ampliп¬Ѓer. …

Articles

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  Zero-Bias Detector Yields High Sensitivity with Nanopower Consumption &mdash LT Journal
  PDF, 195 Kb, File published: Feb 1, 1998
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  DESIGN IDEAS Zero-Bias Detector Yields High Sensitivity
  with Nanopower Consumption
  by Mitchell Lee
  RF ID tags, circuits that detect a
  “wake-up” call and return a burst of
  data, must operate on very low quiescent current for months or years, yet
  have enough battery power in reserve
  to answer an incoming call. For smallest size, most operate in the ultrahigh
  frequency range, where the design of
  a micropower receiver circuit is problematic. Familiar techniques, such as
  direct conversion, super regeneration
  or superhetrodyne, consume far too
  much supply current for long battery
  life. A better method involves a
  technique borrowed from simple fieldstrength meters: a tuned circuit and
  a diode detector.
  Figure 1 shows the complete circuit,
  which was tested for proof-of-concept
  at 445MHz. This circuit contains a
  couple of improvements over the standard L/C-with-whip field-strength
  meter. Tuned circuits aren’t easily
  constructed or controlled at UHF, so
  a transmission line is used to match …

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Manufacturer's Classification

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