SE9029X

SE9029X is a constant-current/constant-voltage lithium battery charge controller based on a current-mode PWM buck switching architecture. The charge current is set by a sense resistor connected externally between the SEN and BAT pins, and the float voltage for a single cell is internally set to 4.20V/4.35V (typical). The charge cycle begins when the VIN input voltage exceeds the battery voltage by more than 100mV. At the start of the charge cycle, if the battery voltage is below the trickle charge threshold, the charger IC enters trickle charge mode, with the trickle charge current internally set to 1/10 of the full charge current. Once the battery voltage exceeds the trickle charge threshold, the charger enters full-current CC mode. In CC mode, the charge current is set by an external sense resistor R5 in conjunction with an internal 100mV reference voltage. As the battery voltage approaches the float voltage, the charge current begins to decrease. When the charge current drops to 1/10 of the full charge current, the charge cycle terminates; the internal comparator turns off the pull-down NMOSFET at the CHRG pin, leaving the CHRG pin in a high-impedance state. To restart the charge cycle, the input voltage can be removed and reapplied, or the charger can be disabled momentarily. Likewise, if the battery voltage falls below the recharge threshold voltage, a new charge cycle begins. Once the battery is fully charged, if the input voltage is not removed, the charger shuts down; when the input voltage is removed, the charger enters sleep mode, which greatly reduces battery current consumption and extends standby time.

Applications

• Backup power supply
• Portable devices
• Li-ion battery charger
• Handheld devices

Key features

• Single-cell Li-ion battery, CC/CV charging mode
• Switching-mode operation for fast, efficient, and simple charging management
• Three-stage charging management
• Built-in reverse current protection, no external diode required
• Integrated protections: undervoltage protection, chip over-temperature protection
• Available in DFN3*3-8 and SOP8-EP packages
• 1MHz (Typ) fixed switching frequency
• MPPT charging efficiency up to 90%+
• Charge voltage 4.2V/4.35V ±1%
• Externally configurable charge current
• Trickle charging
• Automatic recharge
• Sleep mode
• Dual-LED charge status indication