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Application Notes

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  A Thermoelectric Cooler Temperature Controller for Fiber Optic Lasers: Climatic Pampering for Temperamental Lasers &mdash AN89
  PDF, 1.6 Mb, File published: Apr 1, 2001
  This application note presents circuitry for maintaining 0.01°C temperature control of fiber optic lasers over wide ambient range variations. The circuitry also features high efficiency power delivery, compact size and low noise. Detailed descriptions of circuitry and results are given with special emphasis on thermal loop optimization. An appended section covers practical considerations for thermoelectric cooler-based control loops.
  Extract from the document

  Application Note 89
  April 2001
  A Thermoelectric Cooler Temperature Controller
  for Fiber Optic Lasers
  Climatic Pampering for Temperamental Lasers
  Jim Williams
  INTRODUCTION
  Continued demands for increased bandwidth have resulted in deployment of fiber optic-based networks. The
  fiber optic lines, driven by solid state lasers, are capable of
  very high information density. Highly packed data schemes
  such as DWDM (dense wavelength division multiplexing)
  utilize multiple lasers driving a fiber to obtain large multichannel data streams. The narrow channel spacing relies
  on laser wavelength being controlled within 0.1nm (nanometer). Lasers are capable of this but temperature
  variation influences operation. Figure 1 shows that laser
  output peaks sharply vs wavelength, implying that laser
  wavelength must be controlled well within 0.1nm to maintain performance. Figure 2 plots typical laser wavelength
  vs temperature. The 0.1nm/В°C slope means that although
  temperature facilitates tuning laser wavelength, it must
  not vary once the laser has been peaked. Typically, temperature control of 0.1В°C is required to maintain laser
  operation well within 0.1nm. Temperature Controller Requirements
  The temperature controller must meet some unusual
  requirements. Most notably, because of ambient temperature variation and laser operation uncertainties, the controller must be capable of either sourcing or removing heat
  to maintain control. Peltier-based thermoelectric coolers …

Articles

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  The LTC1658 and LTC1655: Smallest Rail-to-Rail 14-Bit and 16-Bit DACs &mdash LT Journal
  PDF, 34 Kb, File published: Feb 1, 1999
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  DESIGN INFORMATION The LTC1658 and LTC1655: Smallest
  Rail-to-Rail 14-Bit and 16-Bit DACs
  by Hassan Malik
  Expanding the rail-to-rail, voltage
  output DAC family, Linear Technology introduces two new voltage output
  DACs that break the size/bits barrier. The LTC1658 is a 14-bit
  rail-to-rail voltage output DAC in a
  tiny MSOP-8 package and the
  LTC1655 is a 16-bit voltage output
  DAC in an SO-8 package. Both of
  these DACs also provide a convenient
  upgrade path for users of LTC’s 12bit voltage output DAC family. The
  LTC1658 draws only 270ВµA from a
  3V or 5V supply and is 14-bit monotonic over temperature. The LTC1655
  draws 600ВµA from a 5V supply and is
  16-bit monotonic over temperature.
  2.7V TO 5.5V 8 These DACs have a flexible 3-wire
  serial interface that is SPI/QSPI and
  MICROWIRE compatible.
  Figures 1 demonstrates the ease of
  using the LTC1658. The output swings
  from 0V to VREF at full-scale. VREF
  should be less than or equal to VCC to …

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  Infinite Sample-and-Hold Outperforms Many Legacy Sample-and-Hold Amplifiers &mdash LT Journal
  PDF, 159 Kb, File published: Nov 1, 2000
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  DESIGN IDEAS Infinite Sample-and-Hold Outperforms
  Many Legacy Sample-and-Hold
  Amplifiers
  by Derek Redmayne
  Many applications requiring
  sample-and-hold amplifiers have been
  left high and dry by the dearth of
  these devices in today’s catalogs. The
  use of an ADC followed by a DAC can
  provide this function, as well as producing characteristics not possible
  with a conventional sample-and-hold.
  The circuit shown in Figure 1 is a
  simple and compact implementation
  of a topology referred to as an “infinite
  sample-and-hold.” It does not, in fact,
  hold for an infinite length of time but
  will do so until the power is turned off
  or until a new sample is required. The
  reason it is termed “infinite” is that it
  does not droop. It is formed from an
  ADC feeding a DAC. There is no droop
  because the sample is held as a digital code in the registers of the DAC.
  The overall accuracy of the infinite …

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Manufacturer's Classification

• Data Conversion > Digital-to-Analog Converters (DAC) > Voltage Output DACs | Unipolar Digital-to-Analog Converters (DAC)