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Charger IC targets portable apps

Posted: 21 Jun 2005 ?? ?Print Version ?Bookmark and Share

Keywords:intersil? isl6299? battery charger ic? li-ion? polymer?

Intersil Corp. released its ISL6299 advanced high voltage dual-input battery charger IC for single-cell Li-ion/polymer applications. The charger accepts power inputs from the USB port or desktop cradle/AC adapter, supporting applications like cellphones, smart phones, PDAs, MP3 devices, portable multi-media players and digital still cameras. According to the company, this chip is an ideal charger for smart handheld devices that need to communicate with a PC via the USB port. It's features allow portable units to be charged from two alternative sources (USB or desktop cradle/AC adapter) while protecting portable devices from high input voltages and minimizing temperature rise during charging.

"The ISL6299's high input voltage offers a much more robust solution while alleviating the need for expensive over-voltage protection circuitry," said Andrew Baker, product marketing manager of Intersil's handheld power management group. "The device's end-of-charge (EOC) programming provides more flexibility to customize the charge function for the termination function for a particular application and the EOC latch prevents false end-of-charge indications."

The ISL6299 features maximum input voltages of 28V (cradle) and 7V (USB). With the 28V cradle rating, low-cost (large output-tolerance) adapters can safely be used, said Intersil. And when both inputs are powered, the cradle input is used to charge the battery. The charge current is programmable for the cradle input with a small resistor. The end-of-charge current for the cradle input is also programmable by another external resistor. The new charger IC incorporates Thermaguard technology, which protects the chip against over temperature during charging. If the die temperature rises above a typical value of 100C, a thermal foldback function reduces the charge current automatically to prevent further temperature rise.

The ISL6299 pre-conditions the battery with low current when the battery voltage is below 2.6V. The device has two indication pinsthe power present (PPR) pin that outputs an open-drain logic LOW when either the cradle or the USB input power is attached, and the charge (CHG) pin that indicates a logic LOW when the charge current is above a minimum current level. When the charge current is below the minimum current, the CHG pin indicates a logic HIGH signal and the status is latched. The latch resets when the device is disabled and re-enabled, when the selected input source has been removed and re-applied, when the USBON turns LOW, or when the BAT pin voltage falls below the re-charge threshold.

The ISL6299 is available in Pb-free, 10-lead 3-by-3mm DFN packages, in tube or tape and reel. The ISL6299IRZ-T has a suggested resale price of $1.30 in 1,000-unit quantities. An evaluation board (ISL6299EVAL1) is also available.

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