Abstract
In this paper, a mode-selectable synchronous buck DC-DC converter with high efficiency and low quiescent current is proposed, which is suitable particularly for use as an Li-ion battery charger. The high efficiency is obtained by applying dynamic power management technology under light load, which makes some modules of the chip enter into sleep state and the quiescent current of the whole chip down to 45 μA. At the same time, power metal-oxide semiconductor (MOS) devices are also shut down to decrease the dissipation of the system. A simple loop compensation method is also proposed, which can eliminate the influence brought by the high equivalent resistance of the output's capacitor on the stability of the system loop. The converter has been made with a 0.5- μm complementary MOS process. Experimental results show that the peak efficiency is 94% at an output current of 100 mA when the supply voltage is 2.7 V. Moreover, the output voltage can recover within 14 μs at 400-mA load step.
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