Low-quiescent-current flexible mode buck–boost converter

In this study, a mode-flexible buck/boost converter with four operation modes aiming at improving efficiency and extending battery life in portable devices is proposed. When the battery supply decreases or increases, the transition is smooth and the mode can be chosen flexible. High efficiency is obtained because of the introduction of buck-boost mode in pulse-width modulation and the burst mode under light load. The converter can work in an appropriate mode according to the current sensing block, which is suitable for lithium battery and power bank. Whole chip obtains 35 μA low-quiescent current in standby mode and 45 μA low-quiescent current in burst mode. Experimental results show that the peak efficiency is 95% at an output 1 A when the supply voltage is 4.2 V. The peak output ripple is 60 mV in BURST mode and 20 mV in constant current mode.