QN4056

QN4056 is a complete, constant-current/constant-voltage linear charger IC designed for single-cell lithium-ion batteries. It employs an internal PMOSFET architecture with integrated reverse-charge protection, eliminating the need for an external isolation diode. An internal thermal feedback mechanism automatically adjusts the charge current to control junction temperature during high-power operation or in elevated-temperature environments. The charge current is set via an external resistor; when the charge current drops to 1/10 of the programmed value after the final float voltage is reached, the IC automatically terminates the charge cycle. When input power is removed, the IC enters a low-current state, reducing battery leakage current to below 2uA. The IC also supports a shutdown mode in the active state, reducing supply current to 55uA. Additional features include temperature sensing, undervoltage lockout, automatic recharge, and two LED status pins for indicating charge status and charge termination. The QN4056 is available in an ESOP-8 package with an exposed thermal pad for enhanced heat dissipation. Its minimal external component count makes it an ideal solution for portable applications.

Applications

• MP3/MP4
• GPS
• Digital cameras
• Mobile phones/PDA
• Portable devices/chargers

Key features

• Single-cell Li-Ion battery charging, no external MOSFET, sense resistor, or blocking diode required
• Constant-current/constant-voltage charging with thermal regulation for maximum charge rate without risk of overheating
• Preset charge voltage: 4.2V, ±1% accuracy
• Charge current monitor output for battery fuel gauging
• Charge status, battery absence, and fault status indication
• Automatic recharge
• 2.9V trickle charging
• Programmable charge current up to 1000mA
• Soft-start to limit inrush current
• Supply current in standby mode: 55uA
• Integrated battery temperature monitoring
• C/10 charge termination
• ESOP-8 package