WST4054

WST4054 is a complete constant-current/constant-voltage linear charger IC for single-cell lithium-ion batteries. Its SOT package and minimal external component count make it ideal for portable applications. The WST4054 is compatible with both USB power supplies and adapter power sources. The internal PMOSFET architecture, combined with reverse-charge protection circuitry, eliminates the need for external sense resistors and isolation diodes. Thermal feedback regulates the charge current to limit die temperature during high-power operation or elevated ambient temperature conditions. The charge voltage is fixed at 4.2V, while the charge current is externally programmable via a single resistor. When the charge current drops to 1/10 of the programmed value after reaching the final float voltage, the WST4054 automatically terminates the charge cycle. When the input voltage (AC adapter or USB power) is removed, the WST4054 automatically enters a low-current state, reducing battery leakage current to below 2uA. The WST4054 can also be placed in shutdown mode, reducing supply current to 45uA. Additional features include a charge current monitor, undervoltage lockout, automatic recharge, and a status pin for indicating charge termination and input voltage presence.

Applications

• Cellular phones
• PDA
• MP3 players
• Charging docks
• Bluetooth applications

Key features

• Charge current adjustable up to 500mA
• No MOSFET, sense resistor, or isolation diode required
• Thermal regulation with constant-current/constant-voltage operation maximizes charge rate without risk of overheating
• Direct single-cell Li-Ion battery charging from USB port
• Preset 4.2V charge voltage with ±1% accuracy
• 2.9V trickle charge threshold
• 45μA supply current in standby mode
• Integrated charge status indicator simplifies peripheral circuitry
• 5-pin SOT-23 package