Battery charger accepts two power sources

Intersil introduces the ISL9214, a fully integrated low-cost single-cell Li-ion or Li-polymer battery charger. The ISL9214 is an ideal charger for smart handheld devices that need to communicate with a personal computer via a USB.

The charger accepts two power inputs, normally one from a USB (Universal Serial Bus) port and the other from a desktop cradle. When both inputs are powered, the cradle input is used to charge the battery.

“Due to the 28V-rated inputs for the cradle and USB, the ISL9214 offers an extra level of protection to a Li-ion battery from charging system failures. With its 28V input rating, large, low-cost output tolerance adapters can be used safely,” said Andrew Rhind, vice president and general manager for Intersil's Consumer Power products group. “Because the ISL9214 provides dual input power sources for the cradle and USB, minimal components are necessary, offering the customer cost and board space savings.”

The ISL9214's charge current is programmable for the cradle input with a small resistor. The end-of-charge current is also programmable by another external resistor. The charger incorporates Thermaguard which protects the IC against over- temperature. If the die temperature rises above a typical value of +125°C, a thermal foldback function reduces the charge current automatically to prevent further temperature rise.

The charger has two indication pins. The PPR (power present) pin outputs an open-drain logic LOW when either the cradle or the USB input power is attached. The CHG (charge) pin is also an open-drain output that indicates a logic LOW when the charge current is above a minimum current level.

When the charge current of the ISL9214 is below the preset minimum current, the CHG pin will indicate a logic HIGH signal. This status is latched and will be reset under one of these events: (1) the part is disabled and re-enabled; (2) the selected input source has been removed and reapplied, (3) the USBON turns LOW, or (4) the BAT pin voltage falls below the recharge threshold (~4.0V).

Key Features

  • Complete charger for single-cell Li-ion/polymer batteries
  • Dual input power sources for cradle and USB
  • Low component count
  • Integrated pass elements
  • Fixed 380mA USB charge current
  • Programmable cradle charge current
  • Charge current Thermaguard for thermal protection
  • 28V maximum voltages for cradle and USB inputs
  • Adapter presence and charge indications
  • Less than 0.5μA leakage current off the battery when no input power attached
  • Programmable end-of-charge current
  • Ambient temperature range: -40°C to +85°C
  • No external blocking diode required
  • Pb-free plus anneal available (RoHS compliant)

    Target Applications

    • Smart handheld devices
    • Cell phones, PDAs, MP3 players
    • Digital still cameras
    • Handheld test equipment

    The ISL9214 is available now in a 10-lead DFN package and is priced at $1.25 in 1,000-unit quantities. For more information on the ISL9214, visit,1477,ISL9214,0.html.

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