A Wide-Load-Range Constant-Charge-Auto-Hopping Control Single-Inductor-Dual-Output Boost Regulator With Minimized Cross-Regulation

A novel single-inductor-dual-output (SIDO) boost regulator with sequential-control is presented. This control can handle large loads or unbalanced loads with minimized cross interference between channels. A constant-charge-auto-hopping (CCAH) control is also presented to further extend the power handling 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 N = 2 to 7 according to the total loads and during load transient. To minimize cross-regulation during frequency hopping, the inductor peak current is set to a predefined value according to the switching frequency information 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 mu m CMOS process to verify the effectiveness of the CCAH control. 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 efficiency of 91.6% is achieved 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 observed with a less than 200 mA load current change.