CXLB73257 is a PFM boost type dual cell lithium battery charging control integrated circuit that operates between 2.75V and 6.5V. CXLB73257 adopts constant current and quasi constant voltage mode (CVTM) for battery charging management. It integrates a reference voltage source, an inductor current detection unit, a battery voltage detection circuit, and an on-chip MOSFET. It has the advantages of fewer external components and a simple circuit. When the input power is turned on, CXLB73257 enters the charging state, and the N-channel MOSFET inside the control chip is turned on, causing the inductor current to rise. When it reaches the upper limit set by the external current detection resistor, the N-channel MOSFET inside the chip is turned off, the inductor current decreases, and the energy in the inductor is transferred to the battery. When the inductor current drops to the lower limit set by the external current detection resistor, the on-chip N-channel MOSFET conducts again, and so on. When the BAT pin voltage reaches the internally set 8.4V (typical value) for the first time, CXLB73257 enters quasi constant voltage charging mode to charge the battery with a smaller current. In quasi constant voltage mode, when the BAT pin voltage reaches 8.4V, the charging process ends and the on-chip N-channel MOSFET remains in the off state. When the BAT pin voltage drops to the recharge threshold, CXLB73257 enters the charging state again. The maximum operating frequency of CXLB73257 can reach 1MHz. When the battery voltage is lower than the input voltage or the battery is short circuited, CXLB73257 continues to charge the battery with a smaller current under the joint action of the on-chip N-channel MOSFET and the off chip P-channel MOSFET, providing protection for the battery. Other functions include chip enable input, chip over temperature protection, and status indication output terminal. CXLB73257 adopts a 3mm x 3mm 12 pin DFN package.
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[ CXLB73257 ]"
