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Design Notes

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  Power Solutions for the Device Bay &mdash DN197
  PDF, 77 Kb, File published: Jan 1, 1999
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  Power Solutions for the Device Bay – Design Note 197
  Ajmal Godil
  “Device Bay” is an industry specification defining a
  mechanism for easily adding and upgrading PC peripheral
  devices to a live system without opening the chassis
  or shutting off the power. This requires Hot Swapв„ў
  capability for the Device Bay to ensure the integrity of
  users’ data and applications. For example, a CD-R drive
  could be added to provide a large storage medium for
  digital imaging or a DVD drive could be added to enable DVD video playback. The Device Bay specification
  applies to all classes of computers, including desktop,
  mobile, home and server computers. Device Bay comes
  in three form factors:1 DB32, DB20 and DB13. The
  DB32 is designed for desktops with a maximum power
  consumption of 25W, DB20 is designed for laptops and
  desktops with a maximum power consumption of 4W
  and DB13 is designed for laptops with a maximum power
  consumption of 4W. The DB20 and DB13, on the other hand, only need 5V
  and 3.3V supplies. It is recommended that these supply voltages also increase slowly to minimize current
  spikes. Figure 1 shows a block diagram of a circuit that
  controls the rise time of the various voltage sources on
  the device side and the system side for the DB32 form
  factor. The maximum allowable currents for various …

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  Multiple Power Supplies Track During Power Up &mdash DN272
  PDF, 96 Kb, File published: Nov 2, 2001
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  Multiple Power Supplies Track During Power Up
  Design Note 272
  Vladimir Ostrerov
  Introduction
  Many modern circuits require multiple power supplies
  that must turn on in a certain order to avoid damaging sensitive components. In many cases, forcing the
  supplies to ramp up together is the preferred solution.
  Unfortunately, this can be difficult when the supplies
  are generated from multiple sources, each with its own
  power-up timing and transient response. However, there
  is a simple solution for up to п¬Ѓve supplies ramping up
  simultaneously.
  The circuit shown in Figure 1 solves this problem by
  placing an N-channel MOSFET between the output of
  each power supply and the load. When power is п¬Ѓrst applied to the circuit, the MOSFETs are turned off and
  each power supply is allowed to power up at its own
  rate. Once each power supply has settled, the common
  gates of the MOSFETs are ramped up, forcing the outputs to ramp up simultaneously as shown in Figure 2.
  Five Supply Voltage Tracker Circuit
  The key components of the circuit in Figure 1 are the
  LTC В®1728-1.8 triple supply monitor and the LTC1422
  single Hot Swapв„ў controller. The LTC1728-1.8 directly
  monitors three supply outputs: 5V, 1.8V and 1.5V. The …

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  Low Voltage Hot Swap Controller Ignores Backplane Noise and Surges &mdash DN319
  PDF, 84 Kb, File published: Sep 1, 2003
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  Low Voltage Hot Swap Controller Ignores Backplane Noise
  and Surges – Design Note 319
  Mitchell Lee
  First generation single supply Hot Swapв„ў controllers,
  such as the LTC В®1422, combine the features of various
  discrete inrush limiting circuits into a single IC, including
  an electronic circuit breaker, adjustable power-up rate,
  reset output, high side MOSFET gate drive, undervoltage
  lockout and a wide operating voltage range. The LTC4211
  advances these features by adding a dual level, dual
  response time electronic circuit breaker, adjustable softstart with inrush current limiting, fault detection, faster
  response time to severe overloads and operation from
  2.5V to 16.5V—all in a small 10-lead MSOP package.
  Control 25W with a 10-Lead MS Package
  Figure 1 shows a 5V, 5A Hot Swap application designed
  for inclusion on a removable circuit board. As is customary, the circuit board ground and VCC planes are wired
  to long connector pins, eliminating reliability problems
  associated with pin-to-receptacle arcing. Until the PC
  board is п¬Ѓrmly seated in the backplane, the MOSFET
  switch remains safely off and isolates CLOAD (typically
  100ОјF or more) from the backplane. Once the connector
  is fully seated, the R1-R2 divider which serves both as a
  connection sense and an undervoltage lockout, activates …

Articles

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  Ramp Three Supplies with a Supply Monitor and Hot Swap Controller &mdash LT Journal
  PDF, 235 Kb, File published: May 1, 2001
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  DESIGN IDEAS Ramp Three Supplies with a Supply
  Monitor and Hot Swap Controller
  by Mitchell Lee
  Many digital systems with multiple
  supply voltages require simultaneous
  ramping of supplies at power up. Since
  the power supply usually consists of
  separate regulators for each voltage,
  it is impossible to guarantee simultaneity of output. The circuit shown in
  Figure 1 ramps the outputs of three
  supplies and ensures tracking at
  power up and during recovery from a
  fault.
  Regulators invariably start up at
  different rates and different times
  based on current capability, filter
  capacitance and loop characteristics,
  so there are no guarantees as to how
  or when the outputs will rise to their
  respective voltages. In this case, an
  LTC1728-2.5 triple supply monitor
  keeps watch over each of three regulated supplies (1.8V, 2.5V and 3.3V).
  continued on page 27 Q1 1.8V/15A …

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Manufacturer's Classification

• Monitor, Control and Protection > Hot Swap Controllers > Low Voltage Hot Swap Controllers