Datasheet Linear Technology LT1505

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Design Notes

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  Li-Ion Charge Termination IC Interfaces with PWM Switchers &mdash DN242
  PDF, 74 Kb, File published: Oct 2, 2001
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  Li-Ion Charge Termination IC Interfaces with PWM Switchers
  Design Note 242
  Fran Hoffart
  Rechargeable lithium-ion batteries are rapidly becoming the battery of choice for many battery-powered
  products. These products include notebook computers, PDAs, video camcorders, digital cameras, cellular
  phones, portable test equipment and others. Compared
  to other rechargeable power sources, Li-Ion batteries
  have higher energy density for both weight and volume
  and provide longer run time between charges. tery from overtemperature and overcurrent conditions.
  In addition, battery packs may also contain back-toback MOSFET switches that disconnect the battery if
  an overcurrent condition exists for either charge or
  discharge, or if an overvoltage or undervoltage condition exists. Many of these precautions are needed
  because lithium-ion cells are easily damaged by both
  overcharge and overdischarge conditions. Charging Li-Ion batteries is a relatively simple process.
  Apply a current-limited (at a 1C rate) constant voltage
  (В±1% tolerance) for approximately three hours, then
  stop charging. (C is a battery term used to indicate
  the Ampere-hour capacity of a battery). A complete
  charge cycle may also include precharge qualification
  for battery temperature and precharge qualification for
  deeply discharged batteries. LTВ®1510 Battery Charger IC
  The LT1510 is a high efficiency switching regulator
  power IC designed speciп¬Ѓcally for battery charging …

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  Simple Li-Ion Charge Termination Using the LT1505 &mdash DN244
  PDF, 73 Kb, File published: Nov 2, 2001
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  Simple Li-Ion Charge Termination Using the LT1505
  Design Note 244
  Mark Gurries The LT1505 provides a logic signal output called
  “FLAG” that is intended to help implement a Li-Ion
  charge termination mechanism. In the constant voltage portion of the charge cycle, the battery continues
  to accept charge and the charge current continues to
  drop. When the charge current drops below 20% of
  the full-scale value, the FLAG output goes low.
  Normally, the FLAG function is used to let the system
  know that the battery is nearly fully charged. However,
  the flag can also be used to change the time scale of
  the overall charge-cycle timer and convert it to a topoff charge timer. Thus, the user gets a battery that
  is almost fully charged, but the charger remains on
  so that the remaining time can be used to charge the
  battery to 100%, after which the charger will turn off.
  The nature of Li-Ion battery charging is such that the
  battery spends about half of the total charge time
  receiving about 85% of its capacity and the remaining
  half to receive the last 15%. The LT1505’s 20% current
  threshold represents a compromise between charge
  time and a fully charged battery. It represents around
  85% of a typical battery’s charge capacity.
  11/00/244_conv 5 1C CHARGE RATE …

Articles

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  Fast Rate Li-Ion Battery Charger &mdash LT Journal
  PDF, 58 Kb, File published: Feb 1, 1999
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  DESIGN FEATURES Fast Rate Li-Ion Battery Charger
  by Goran Perica Introduction
  The recent trend in notebook computers has been toward increasing
  battery operating time and faster
  processor speeds. These two requirements, in conjunction with a need for
  faster battery recharging (1–2 hours)
  have placed a strain on battery charging circuits and wall adapters. A
  typical notebook computer system
  configuration is shown in Figure 1.
  Wall adapters are typically AC/DC
  converters with a 20V output at
  3A–4A of load current. When a notebook computer is running, all of the
  available current from the wall adapter
  may be consumed by the system,
  with no power left for charging the
  battery. However, as soon as the
  system’s power requirements drop
  below the wall adapter’s current limit,
  the battery charging can resume. In
  order to recharge the battery in the
  shortest time possible, the recharging should start as soon as there is
  any current left over from the system.
  The ideal situation is when the sum of …

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• Power Management > Battery Management > Battery Charger IC > Switching Battery Chargers