CN3306

CN3306 is a current-mode fixed-frequency PWM boost-type multi-chemistry battery charge management IC. With an input voltage range of 4.5V to 32V and minimal external components, CN3306 offers simple and flexible application, suitable for charge management of lithium-ion, LiFePO₄, or lithium titanate batteries. CN3306 integrates a bandgap reference, a 330KHz oscillator, an error amplifier, a charge control unit, a current-mode PWM control unit, a chip shutdown circuit, a soft-start circuit, and a gate drive circuit. Current-mode control improves transient response and simplifies loop compensation. When the VCC pin voltage exceeds the UVLO threshold, the charger operates normally and charges the battery. If the battery voltage is below the set constant-voltage charge voltage, the charger enters CC mode, where the charge current is set by the internal 0.12V reference voltage and an external resistor RCS — i.e., charge current = 0.12V/RCS. As the battery voltage rises toward the constant-voltage charge voltage, the charger transitions to CV mode and the charge current gradually decreases. When the charge current drops to 16.6% of the CC charge current, CN3306 enters end-of-charge mode: the transistor inside one open-drain output pin turns off, presenting a high-impedance output; the transistor inside the other open-drain output pin turns on, pulling the output low to indicate end-of-charge status. In end-of-charge state, disconnecting and reconnecting the input power will initiate a new charge cycle. Alternatively, if the battery voltage drops to the recharge threshold (95.8% of the constant-voltage charge voltage), a new charge cycle will also start automatically. CN3306 employs a constant-voltage method to track the solar panel maximum power point. The solar panel voltage is divided by two resistors and fed back to the MPPT pin; in MPPT state, the MPPT pin voltage is regulated to 1.205V. CN3306 also incorporates an overvoltage comparator. If the BAT pin voltage rises due to load transients or sudden battery removal, and reaches the overvoltage threshold, the overvoltage comparator activates and turns off the external N-channel MOSFET, temporarily suspending charging until the BAT pin voltage falls back below the overvoltage release threshold. CN3306 includes an internal soft-start circuit to reduce inrush current at power-up. Additional features include chip shutdown, a built-in 5V voltage regulator, and slope compensation.

Applications

• Bluetooth applications
• POS terminals
• Laptops
• Power banks
• Charge management for Li-ion, LiFePO₄, or Li₄Ti₅O₁₂ batteries

Key features

• PWM boost mode charge management
• Input voltage range: 4.5V to 32V
• Adaptive charging current
• Solar panel maximum power point tracking (MPPT) for solar-powered operation
• Switching frequency: 330kHz
• High-side current sensing
• Current modulation threshold: 120mV
• Per-cycle inductor current limiting
• Internal slope compensation
• Battery terminal overvoltage protection
• Constant current / constant voltage (CC/CV) charging mode
• Automatic recharge
• Charging and end-of-charge status indication
• Internal soft-start circuit
• Built-in 5V voltage regulator
• Low shutdown current
• Operating temperature range: -40°C to 85°C
• TSSOP-16 package
• Lead-free, RoHS compliant, halogen-free