Intersil Corporation, a world leader in the design and manufacture of high-performance analogue semiconductors, introduced 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. 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.
Flexibility and safety
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).
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)
Smart handheld devices
Cell phones, PDAs, MP3 players
Digital still cameras
Handheld test equipment