Cxlb7270 is a PFM boost battery charging control IC, which works from 4V to 28V. The cxlb7270 is internally integrated with a reference voltage source, + 5V voltage modulation unit, inductive current detection unit, battery voltage detection circuit and off chip n-channel MOSFET Driver circuit, etc. it has the advantages of few external components and simple circuit. When the input power is turned on, the cxlb7270 enters the charging state, the n-channel MOSFET outside the control chip is turned on, and the inductance current rises. When it rises to the upper limit of the external current detection resistance setting, the n-channel MOSFET outside the chip is cut off, the inductance current drops, and the energy in the inductance is transferred to the battery. When the inductor current drops to the lower limit of the external current detection resistance setting, the off chip n-channel MOSFET is turned on again, and so on. The battery voltage is fed back to the FB pin through the resistance voltage division network. When the FB pin voltage reaches 1.205v (typical value), the charging process is over and the off chip n-channel MOSFET remains in the cut-off state. When the FB pin voltage drops to the recharging threshold, the cxlb7270 enters the charging state again. The maximum operating frequency of cxlb7270 can reach 1MHz, and the operating temperature range is from - 40 ℃ to + 85 ℃