An ultralow-quiescent current dc-dc buck converter with a single controller is presented to achieve high efficiency over a wide load range for Internet of Things application, which is achieved by utilizing adaptive on-time control topology. An on-demand modulation strategy and sleep-time detector are proposed to attain sub-μA quiescent current consumption under ultralight load condition. The adaptive-bias and adaptive-gain (A ² ) comparator is presented to improve the loop stability caused by the inherent propagation delay of the low-power comparator. Moreover, a novel on-time generator is proposed to fix the switching frequency in continuous conduction mode. The proposed buck converter was implemented by using a 0.18-μm CMOS process with an area of 1.092 mm ² . It achieves a peak efficiency of 95.8% and >90% efficiency from 10 μA to 300 mA. A 240-nA quiescent current, including bandgap voltage and current reference, is achieved. With a low output ripple of less than 20 mV, the input voltage range and regulated output voltage are 2.1-5.5 and 1.8 V, respectively.

Primary-side regulation (PSR) flyback converters operating in discontinuous conduction mode (DCM) are widely used in low-power applications. In DCM, the peak current control method for PSR flyback is generally adopted to achieve constant current (CC) output. However, there is few effective schemes suitable for DCM and continuous conduction mode (CCM) operation of PSR flyback converters due to the difficulty in estimating the output information correctly, especially in the case of analog circuit control. In this paper, a control scheme based on mid-point sampling method is proposed to achieve a high-precision CC control, which operates seamlessly as the operating mode switched between DCM and CCM. Besides, the closed-loop CC control is used to improve significantly the loop stability and accuracy of system compared to conventional open-loop CC control scheme. In order to verify the feasibility and performance of the proposed control, a control IC with the proposed CC control scheme has been implemented in 0.18μm 5V/40V BCD process. The experimental results show that the deviation of the output current is within ±1.93% under different input and load conditions.

This paper presents a multi-mode boost converter to achieve the high efficiency over a wide input voltage range for thermoelectric energy harvesting (TEH) applications. Under high, medium, and low input voltages, continuous conduction mode (CCM), critical conduction mode (CRM), and discontinuous conduction mode (DCM) are adopted to improve the conversion efficiency, respectively. Moreover, a constant peak current (CPC) control scheme is proposed to realize high efficiency under ultra-low input voltage. The proposed converter is implemented in a $0.18 \mu \text{m}$ standard CMOS process, which occupies a chip core area of about 1.0 mm $\times0.9$ mm. It achieves >60% efficiency in the range of TEG open-circuit voltage $V_{S}$ from 20 mV to 500 mV, and a peak efficiency of 91.4%. Moreover, after the startup is completed, an efficiency of 37.1% under the $V_{S}$ as low as 10 mV can be achieved.

An adaptive multimode constant voltage (CV) control scheme for primary-side regulation flyback converters operating in discontinuous conduction mode and continuous conduction mode operation is presented, which significantly enhances the light-load efficiency and thereby the overall average efficiency. Compared to conventional control scheme, the proposed control scheme performs analog control approach to integrate multiple operating modes adaptively based on load conditions. Besides, line voltage compensation and freewheeling diode compensation are proposed to improve the CV precision operating in multiple modes. The proposed adaptive multimode control scheme is implemented in 0.18 μ m 5 V/40 V BCD process and occupies a die size (with pads) of 1.05×0.8 mm ² . The experimental results show that the average efficiency is 88.52% under 265 Vac, whereas peak efficiency can reach 89.65% under 265 Vac. The deviation of the output voltage is within ± 2.33%.

The demand for compact battery management systems (BMS) in applications such as two-wheelers and uninterruptible power supplies has driven the development of battery management integrated circuits (BMICs). These BMICs incorporate functions such as battery sensing, fault detection, and protection management. This paper introduces an 18-cell lithium-ion battery sensing and protection BMIC, designed to enable the implementation of a compact BMS. Additionally, a high-order temperature-compensated bandgap reference (BGR) structure, with a temperature coefficient of 5 ppm/^∘C, is proposed to deliver a high-precision reference for sensing and comparison. The chip also integrates power management circuits capable of handling input voltages up to 90 V, thereby powering low-voltage modules. It features an 18-channel multiplexer for selectively detecting high-voltage, series-connected battery packs and achieving on-chip cell balancing through sequential control. Furthermore, a current-sense amplifier and programmable overcurrent protection circuits are included to reliably detect charging and discharging currents in the battery packs. The proposed BMIC occupies an area of 3 mm × 3.3 mm and is fabricated using a 180 nm BCD process. The total current consumption of the chip during normal operation is 65.1 μA, which can be reduced to 2 μA in shutdown mode to minimize long-term battery pack losses.