A 14V-output adaptive-off-time boost converter with quasi-fixed-frequency in full loading range

A monolithic quasi-fixed-frequency DC-DC boost converter with a modified-adaptive-off-time (MAOF) control is presented. To achieve a quasi-fixed-frequency in whole loading range, the new MAOF control is able to overcome the frequency variation problems naturally exist in traditional adaptive-off-time control in both continuous- and discontinuous-conduction-mode (CCM and DCM) operations. The MAOF control boost converter was implemented with a 0.35μm High Voltage (HV) CMOS process. With 3V - 4.2V input voltage, 10V - 14V output voltage and 30mA - 300mA load current range, simulated results show that the switching frequency keeps constant at 960kHz to within ±5% across the whole operation range.