Datasheet Linear Technology LTC1921

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Design Notes

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  Monitor Network Compliant -48V Power Supplies &mdash DN290
  PDF, 85 Kb, File published: Jul 2, 2002
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  advertisement Monitor Network Compliant –48V Power Supplies
  Design Note 290
  Brendan Whelan
  Introduction
  Reliability is a top priority for the designers of
  modern telephone and communication equipment.
  Designers take extra care to protect circuitry from
  failure-causing temperature and voltage changes,
  employing redundancy whenever possible, especially
  for power supplies. The power supplies are monitored
  to obtain early warning of impending failure. Often
  complicated circuitry that can include a voltage reference, comparators, voltage regulator and several
  precision resistor dividers is used. Designers may also
  use discrete components to monitor and indicate the
  state of power supply fuses. The resulting circuitry
  can be expensive in terms of component cost, board
  space and engineering time. The LTC В®1921 replaces
  the complicated monitoring circuitry with a simple
  integrated precision monitoring system contained
  entirely in an 8-lead MSOP package.
  Features
  The LTC1921 is the only integrated solution that can
  monitor two independent –48V power supplies, plus …

Articles

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  Simplify Telecom Power Supply Monitoring with the LTC1921 Integrated Dual -48V Supply and Fuse Monitor &mdash LT Journal
  PDF, 204 Kb, File published: Aug 9, 2004
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  DESIGN FEATURES Simplify Telecom Power Supply
  Monitoring with the LTC1921
  Integrated Dual –48V Supply and
  Fuse Monitor
  by Brendan Whelan
  Introduction How it Works The LTC1921 is the only fully integrated dual –48V supply and fuse
  monitor that meets common telecom
  specifications for supply range warning and that can withstand the high
  transient voltages required by telecom systems. This device improves
  system reliability by monitoring both
  supply inputs at the card edge and
  indicating the status of both supply
  fuses. The input pins are designed to
  withstand the large DC and transient
  voltages that may occur on the backplane supply. The outputs are
  designed to drive up to three LEDs or
  optoisolators, allowing warnings to
  be transmitted across an isolation
  barrier. The LTC1921 achieves high
  accuracy, high reliability and ease of
  use by combining an accurate internal reference, precision comparators
  and trimmed resistor networks in one
  package. Few external components The LTC1921 monitors supply voltages by dividing the voltage internally …

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  Single IC Monitors Redundant -48V Supplies and Fuses without Precision External Components &mdash LT Journal
  PDF, 156 Kb, File published: Dec 1, 2003
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  DESIGN IDEAS Single IC Monitors Redundant –48V
  Supplies and Fuses without Precision
  by Brendan Whelan
  External Components
  Introduction Reliability is a top priority for the
  designers of modern telephone and
  communications equipment. Designers take extra care to protect circuitry
  from failure by employing redundancy
  whenever possible, especially for power
  supplies. Supply voltages and fuses
  are monitored for early warnings of
  impending failure, often via a complicated array of precision components.
  The resulting circuits are expensive in
  terms of component cost, board space and engineering time. The LTC1921
  replaces complicated monitoring
  systems with a simple, yet versatile,
  integrated precision monitoring system contained entirely in an MSOP–8
  or SO–8 package.
  LTC1921 is a high precision, allin-one monitor for redundant –48V
  supplies. This device is the only fully
  integrated dual –48V supply monitor
  that meets common telecom specifications for supply range warning and How it Works D1, MURS320
  RETURN A FUSE A …

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  -48V Backplane Impedance Analyzer Takes the Guesswork Out of Sizing Clippers and Snubbers &mdash LT Journal
  PDF, 432 Kb, File published: Mar 25, 2005
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  DESIGN IDEAS –48V Backplane Impedance Analyzer
  Takes the Guesswork Out of Sizing
  by Mitchell Lee
  Clippers and Snubbers
  It comes as something of a surprise to
  most engineers that the –48V power
  distributed on a backplane exhibits
  a decidedly inductive impedance.
  Considering bypass capacitors are
  often excluded from the backplane,
  coupled with the lengthy path back
  to the –48V battery or power supply
  source, it seems unavoidable. The
  consequences of an inductive driving point impedance are twofold: п¬Ѓrst,
  for reasons entirely cosmetic, the
  ringing associated with insertion and
  other transient events are undesirable.
  Second, input reaction to high dI/dt
  conditions presents correspondingly
  high input voltage surges, placing
  the Hot Swap MOSFET as well as the
  operation of the Hot Swap controller
  at risk. To mitigate these effects a network …

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Manufacturer's Classification

• Signal Conditioning > Comparators > Application Specific Comparators