ISL9228
Dual Input Li-ion/Li-Polymer Battery Charger With Battery Removal Detection

Key Features

• Complete Charger for Single-Cell Li-ion/Polymer Batteries
• Dual Input Power Sources for Cradle and USB
• Battery Removal Detection
• 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
• 1% Constant Voltage Accuracy
• 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 (RoHS Compliant)

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 +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 is below the preset minimum current, the CHG pin will turn to logic high to indicate the end-of-charge condition.

Applications

• Smart Handheld Devices
• Cell Phones, PDAs, MP3 Players
• Digital Still Cameras
• Handheld Test Equipment