Cxlb7211 is an integrated circuit that can charge a single rechargeable lithium battery. The inner part of the device includes a power transistor, which does not need external current detection resistance and resistance diode when applied. Cxlb7211 only needs a few peripheral components, which is very suitable for portable applications. The thermal modulation circuit can control the chip temperature in a safe range when the power consumption of the device is large or the ambient temperature is high. The internal fixed constant voltage charging voltage is 4.2V, which can also be adjusted by an external resistance. The charging current is set by an external resistance. When the input power is powered off, the cxlb7211 automatically enters the sleep mode of low power consumption, and the current consumption of the battery is less than 3 microamps. Other functions include low input voltage latch, automatic recharging, battery temperature monitoring and charging state / end state indication