CN3791

CN3791 is a PWM buck-mode single-cell lithium battery charge management IC that can be powered by a solar panel. It independently manages single-cell lithium battery charging with the advantages of small package size, minimal external components, and ease of use. CN3791 features trickle, constant current, and constant voltage charging modes, making it ideal for lithium battery charge management. In constant voltage mode, CN3791 regulates the battery voltage to 4.2V; in constant current mode, the charge current is set by an external resistor. When the current output capability of the input power source decreases, the internal circuit automatically tracks the maximum power point of the solar panel. Users do not need to consider worst-case scenarios, enabling maximum utilization of the solar panel's output power — making it highly suitable for solar-powered applications. For deeply discharged lithium batteries, when the battery voltage falls below 66.5% (typical) of the constant voltage charging voltage, CN3791 applies trickle charge at 17.5% of the programmed constant current charge level. During the constant voltage charging phase, the charge current gradually decreases; when it drops to 16% of the constant current charge level, charging terminates. In the charge termination state, if the battery voltage falls to 95.5% of the constant voltage charging voltage, a new charge cycle begins automatically. When the input power is removed or the input voltage falls below the battery voltage, CN3791 automatically enters sleep mode. Additional features include input undervoltage lockout, battery overvoltage protection, and charge status indication. CN3791 is available in a 10-pin SSOP package.

Applications

• Power banks
• Handheld devices
• Backup battery applications
• Portable industrial and medical instruments
• Power tools
• Standalone battery chargers

Key features

• Solar panel maximum power point tracking (MPPT)
• Wide input voltage range: 4.5V to 28V
• Complete charge management for single-cell Li-ion battery
• Charge current up to 4A
• PWM switching frequency: 300KHz
• Constant voltage charge voltage: 4.2V±1%
• Constant current charge current set by external resistor
• Trickle charging for deeply discharged batteries
• Automatic recharge function
• Charge status and end-of-charge status indication
• Soft-start function
• Battery terminal overvoltage protection
• Operating temperature range: -40°C to +85°C
• 10-pin SSOP package
• Lead-free, RoHS compliant, halogen-free