A Wide-Load-Range Constant-Charge-Auto-Hopping Control Single-Inductor-Dual-Output Boost Regulator With Minimized Cross-Regulation Xiaocheng Jing, Student Member , IEEE, Philip K. T. Mok , Senior Member , IEEE,a n d M i n gC h a kL e e

Abstract

A novel single-inductor-dual-output (SIDO) boost regulator with sequential-control is presented. This control c an handle large loads or unbalance d loads with minimized cross interference between channels. A c onstant-charge-auto-hopping (CCAH) control is also presented to further extend the power ha n- dling capacity of the regulator with a predictable system switching noise spectrum. The switching frequency of the converter can be automatically hopped between 1 MHz and 1 MHz/N where to 7 according to the total load s and during load transient. To minimize cross-regulation during frequency hopping, the inductor peak current is set to a prede fined value acc ording to the switching frequency informati on from the frequency detection unit to deliver a constant charge per switching period to the unchanged outputs. The response of the transient output is also enhanced with this inductor peak current prediction method. A prototype has been fabricated with a 0.35 mC M O Sp r o c e s st o verify the effectiveness of the CCAH contr ol. With 1.8 V–2.4 V input voltage, two regulated output voltages between 3.0 V and 3.6 V , with maximum 400 mA to 600 mA driving capability and maximum power ef ficiency of 91.6% is achi eved at total output power of 1.15 W. Load transient measurements show that the worst-case cross-regulation is 0.033 mV/mA with a 300 mA load current change at output A and 0.0714 mV /mA with a 280 mA load current change at output B. No noticeable cross-regulation can be