CN3170

CN3170 is a single-cell lithium battery charge management IC that can be powered by solar energy. The device integrates an internal power transistor, eliminating the need for external current sense resistors and blocking diodes. The internal adaptive charging current module automatically adjusts the charging current based on the current output capability of the input power source, so users do not need to design for worst-case conditions and can maximize utilization of the input source's current output capability. This makes it ideal for lithium battery charging applications powered by current-limited sources such as solar panels. CN3170 requires very few external components, making it well suited for portable applications. The thermal regulation circuit keeps the die temperature around 132°C when power dissipation is high or ambient temperature is elevated, preventing excessive junction temperature. The internal fixed constant-voltage charging voltage is 4.2V and can be adjusted upward via an external resistor. The charging current is set by an external resistor. When the input voltage is removed, CN3170 automatically enters a low-power sleep mode, during which the battery current is less than 3μA. Additional features include input undervoltage lockout, automatic recharge, JEITA-compliant battery temperature monitoring, charging current overcurrent protection, and charge status/charge termination status indication. CN3170 is available in a thermally enhanced 8-pin SOP package (eSOP8). CN3170 is a charge management IC for single-cell lithium batteries. The internal power transistor charges the battery in both constant-current (CC) and constant-voltage (CV) modes. The internal fixed CV charging voltage is 4.2V and can be adjusted upward via an external resistor — for example, to 4.35V or 4.4V — for charging ternary lithium batteries. The charging current is set by an external resistor, with a maximum continuous charging current of up to 950mA, requiring no external blocking diode or current sense resistor. CN3170 integrates an adaptive charging current module that automatically adjusts the charging current based on the current output capability of the input power source. Users do not need to design for worst-case conditions; instead, the charging current can be set according to the maximum current output capability of the input source, fully maximizing its utilization. This makes it particularly suitable for lithium battery charging applications powered by current-limited sources such as solar panels. CN3170 provides two open-drain status indicator outputs: a charge status output and a charge termination status output. The internal power management circuit automatically reduces the charging current when the junction temperature exceeds 132°C, allowing users to maximize the device's power handling capability without concern about overheating damaging the IC or external components. Users can therefore design the charging current based on typical conditions rather than worst-case scenarios, since CN3170 will automatically reduce the charging current under worst-case conditions. When the input voltage exceeds both 4.4V and the battery voltage, CN3170 begins charging the battery and the pin outputs a low level, indicating that charging is in progress. If the voltage at the battery voltage sense pin (FB) is below 66.7% of the CV charging voltage, CN3170 pre-charges the battery with trickle current. When the FB pin voltage exceeds 66.7% of the CV charging voltage, CN3170 charges the battery in CC mode, with the charging current determined by resistor RISET connected between the ISET pin and GND. As the FB pin voltage approaches the CV charging voltage, the charging current gradually decreases and CN3170 enters CV mode. When the battery voltage reaches the CV charging voltage and the charging current decreases to the charge termination threshold, the charge cycle ends: the pin enters high-impedance state and the pin outputs a low level, indicating that the charge cycle is complete. The charge termination threshold is 11.2% of the CC charging current. To initiate a new charge cycle, simply cycle the input power off and back on. During the charge termination state, a new charge cycle begins automatically when the charging current rises above IRECH or the battery voltage falls below VRECH. The high-precision internal voltage reference, error amplifier, and resistor divider network ensure that the CV charging voltage accuracy is within ±1%, meeting battery requirements. When the input voltage is removed or falls below the battery voltage, CN3170 enters a low-power sleep mode with battery current consumption less than 3μA, thereby extending standby time.

Applications

• Solar emergency lighting
• Beauty and skin care devices
• Solar chargers
• Portable devices
• Two-cell lithium titanate battery charging
• Various standalone chargers

Key features

• Integrated adaptive charging current module — automatically adjusts charging current based on input source current capability
• Compatible with limited-current voltage sources such as solar panels
• Input voltage range: 4.4V to 6V
• No external blocking diode or current sense resistor required
• Constant voltage charging at 4.2V; adjustable upward via external resistor
• Constant voltage charging settable to 4.35V or 4.4V via external resistor, suitable for ternary lithium battery charging
• Configurable continuous CC charging current up to 950mA
• Overcurrent protection on charging current prevents damage from ISET pin short circuit or incorrect use of abnormally low resistance
• Can be used as a voltage source
• Internal soft-start circuit
• Trickle charge mode at low battery voltage to activate deeply discharged batteries and reduce power consumption
• CC/CV/constant temperature charging mode — maximizes charging current while preventing overheating
• Automatic entry into low-power sleep mode upon supply voltage dropout
• Dual status indication output: charging and charge complete
• Automatic recharge
• JEITA-compliant battery temperature monitoring
• Package: eSOP8
• Lead-free, RoHS compliant, halogen-free