Datasheet Linear Technology LTC3226

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Design Notes

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  Supercapacitor-Based Power Backup System Protects Volatile Data in Handhelds when Power Is Lost &mdash DN498
  PDF, 89 Kb, File published: Dec 21, 2011
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  Supercapacitor-Based Power Backup System Protects Volatile
  Data in Handhelds when Power Is Lost
  Design Note 498
  Jim Drew LTCВ®3226 is a 2-cell series supercapacitor charger with a
  PowerPath™ controller that simplifies the design of backup
  systems. Specifically, it includes a charge pump supercapacitor charger with programmable output voltage and
  automatic cell voltage balancing, a low dropout regulator and
  a power-fail comparator for switching between normal and
  backup modes. Low input noise, low quiescent current and
  a compact footprint make the LTC3226 ideal for compact,
  handheld, battery-powered applications. The device comes
  in a 3mm Г— 3mm 16-lead QFN package. Introduction
  Handheld electronic devices play a key role in our everyday
  lives. Because dependability is paramount, handhelds are
  carefully engineered with lightweight power sources for
  reliable use under normal conditions. But no amount of
  careful engineering can prevent the mistreatment they
  will undergo at the hands of humans. For example, what
  happens when a factory worker drops a bar code scanner, causing the battery to pop out? Such events are
  electronically unpredictable, and important data stored
  in volatile memory would be lost without some form of
  safety net—namely a short-term power holdup system
  that stores sufп¬Ѓcient energy to supply standby power until …

Articles

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  Single-IC Supercapacitor-Based Power Supply Backup Solution &mdash LT Journal
  PDF, 1.9 Mb, File published: Apr 24, 2012
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  Single-IC Supercapacitor-Based Power Supply Backup
  Solution
  Ashish Kirtania Supercapacitors are used in an increasing number of applications that require a ready
  source of backup energy that can be called on to provide short-term power when regular
  input power is lost. In these applications, supercapacitors have a number of advantages
  over traditional energy storage devices such as batteries, including low maintenance
  requirements, virtually unlimited cycle life, and low effective series resistance. The
  LTC3226 simplifies the design of supercapacitor-powered backup application with a
  single-IC solution that charges the supercapacitor when input power is available, and then
  delivers energy from the supercapacitor to the load when nominal input power fails.
  DESCRIPTION Figure 1 shows a typical 3.3V backup supply application in which the main power
  path from the input source to the load
  goes through the external PFET. As long
  as input power is available, the LTC3226
  maintains the supercapacitor stack at a
  full 5V charge. If the input voltage falls
  below 3.15V, the 1.2F supercapacitor stack
  becomes the supply, supporting a 2A load
  at 3.3V for 600ms (See Figure 2). Achieving
  a seamless transition from main supply
  to backup storage requires four principal circuit components: a dual mode (1Г—/2Г—)
  charge pump with automatic cell balance and cell voltage clamp, an LDO to
  supply the load current during backup, …

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Manufacturer's Classification

• Monitor, Control and Protection > PowerPath Controllers & Ideal Diodes
• Power Management > Supercapacitor Chargers