摘要
To power the modern loT devices such as smartwatches, the DCDC converter should have a wide load range to support the increasing functionality of the devices and low quiescent current (IQ) to prolong their battery life. Hysteresis control [1–2] can achieve a low Io at ultra-light load since the controller only needs a low-power comparator. However, the output ripple is greatly increased at the heavy load due to the large delay of the comparator. Multiple mode control [3–6] that usually adopts PWM control at heavy and medium loads, PFM control at light load, and a low-lo controller at ultra-light load is proposed to break the trade-off, but the challenge is how to achieve seamless transition among the different modes without consuming much power. For example, the mode selection relies on external manual switching in [3]. In [4], The load current is sensed and used to determine the operation modes. However, the power consumption of the current sensor is high and thus the light load efficiency is degraded. In [5–6], the load condition is detected by counting the charging pulses in a single period. However, it also results in large output ripple and more noise.