A wide-load-range single-inductor-dual-output boost regulator with minimized cross-regulation by constant-charge-auto-hopping (CCAH) control

A novel single-inductor-dual-output (SIDO) boost regulator with constant-charge-auto-hopping (CCAH) control to minimize the cross interference between channels is presented. In order to have a predictable system switching noise spectrum, the switching frequency of the converter is automatically hopped between 1.25 MHz and 1.25 MHz/N where N = 2 to 5 according to the loads and during transient. A prototype has been fabricated with a 0.35 mum CMOS process to verify the effectiveness of CCAH control. With 1.8 V-2.4 V input voltage, two regulated output voltages between 3.0 V and 3.6V, each with maximum 250 mA driving capability, are provided. Load transient measurements show that the cross-regulation is less than 0.1 mV/mA with a 200 mA change of load current.