利用根据负载电流的大小变换调制模式的方法实现了一种降压型高转换效率的DC/DC开关电源.当控制电压占空比小于20%时,采用伪PFM(pseudo-pulse-frequency modulation)模式调制;占空比大于20%时,采用PWM(pulse-width modulation)模式调制,平均转换效率约为90%,输出电流范围为0.01-3.0A.控制芯片采用0.5μm DPDM CMOS工艺制造,并采用二次集成的方式在封装内部集成了功率p-MOSFET.
A buck DC/DC switching regulator is implemented by automatically altering the modulation mode according to the load current that ranges from 0.01 to 3A. The pseudo-PFM mode is applied when duty cycle is less than 20% ,and the PWM mode is selected in a range of duty cycle from 20% to 100%. The average conversion efficiency of the regulator is about 90% when the output current varies. The proposed dual-mode-control die is implemented in a 0.5μm DPDM CMOS mixed-signal process and a power p-MOSFET is used in the chip by hybrid integration.