ISL9228

Description

The ISL9228 is a fully integrated low-cost single-cell Li-ion or Li-polymer battery charger. The charger accepts two power inputs, normally one from a USB (Universal Serial Bus) port and the other from a desktop cradle. The ISL9228 is an ideal charger for smart handheld devices that need to communicate with a personal computer via USB. The ISL9228 features 28V maximum voltages for both the cradle and the USB inputs. Due to the 28V rated inputs, lowcost, large output tolerance adapters can be used safely. The 28V rating eliminates the over voltage protection circuit required in a low input voltage charger. 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 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 +125C, 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 is below the preset minimum current, the CHG pin will turn to logic high to indicate the end-of-charge condition.