Power saving DC-DC Converter for OLED Driving circuit

摘要

A DC-DC converter having a power saving structure of an OLED(Organic Light Emitting Diode) driving circuit is provided to generate CCM(Chip Control Module) or DCM(Device Control Module) reference voltage by predicting a conversion time of the CCM and the DCM, thereby improving power efficiency when driving an organic electroluminescence panel. A DC-DC converter having a power saving structure of an OLED driving circuit includes a CCM reference voltage generator(20). The CCM reference voltage generator(20) generates a CCM reference voltage in response to a battery voltage(Vbat) and an output voltage of a load estimator(24). A DCM reference voltage generator(22) generates a DCM reference voltage in response to the battery voltage(Vbat) and the output voltage of the load estimator(24). The load estimator(24) outputs a switching signal by predicting a conversion time between a CCM and a DCM. A switch(25) selectively connects the CCM reference voltage generator(20) or the DCM reference voltage generator(22) to a comparator(26) in response to the switching signal. The comparator(26) outputs a reset signal by comparing a ramp waveform with the CCM reference voltage and the DCM reference voltage. An R/S flip flop(28) is reset in response to the reset signal of the comparator(26) and outputs a driving signal of a transistor in response to a pulse clock. A power driving transistor(Q) is driven by the driving signal of the transistor. An inductor(L) converts the battery voltage(Vbat) to current and provides the current to an organic electro-luminescence panel.