The most energy-efficient and most efficient drive circuit oled module

White LED driving circuit by a white LED drive and a peripheral circuit (including transistors, diodes, inductors, capacitors, and resistors, etc.). Drive white LED requires a constant current source, the current is typically 15mA ~ 20mA. The luminance of the LED depends on its forward current, so a plurality of white LED used in tandem, can ensure that the same current flowing through each of the white LED. Forward set for four series white LED 14V voltage, the voltage boost regulator to enhance the single-cell lithium battery (2.7V to 4.2V) it said operating voltage.Low Temperature Display
For example, a single-cell lithium battery (2.7V to 4.2V) power supply high efficiency white LED driver circuit. The SP6682 chosen a standard regulator charge pump circuit. It contains an internal 500kHz oscillator to normal drive pump capacitor, the input voltage doubling. Related to the voltage across the resistor and the SP6682 0.3V the parameter voltage comparator, the drive circuit efficiency of 87%. Typically, commercially available integrated boost regulator as a feedback voltage of 1.24V bandgap reference voltage, and will make relevant across the resistor voltage drop of 1.24V. Thereby the conversion efficiency decreased by 7%. SP6682 0.3V reference voltage is much lower than 1.24V, the decrease in efficiency is proportional to the reference voltage. MOSFET has a small on-resistance and high switching speed, these parameters are superior to other integrated switch. The breakdown voltage of the MOSFET will limit the maximum output voltage by adjusting the voltage to drive the desired number of white-LED system. The regulator can shut down and restart, the brightness of the white LED can be accurately controlled by a PWM signal at the the SP6682 start pin 6.
Double lithium battery (6V to 8.4V) powered white LED driver circuit can choose white LED drivers, the system 3.3V voltage to the VIN pin of the drive, the drive power stage input directly connected to the double lithium battery Ikegami. Typically, the power stage can be connected to any voltage output terminal is lower than the required output voltage. Directly to the input voltage boost topology, the power stage input voltage must be lower than the output voltage or inductor and diode transferred to the output. SW pin allows a maximum voltage of 28 V, to limit the maximum input voltage of the power stage. Associated drive circuit, the higher the input voltage, the higher the efficiency. Therefore, the drive circuit can be completely free from its limited input voltage range, and can effectively save the system cost and board space, but also improve the efficiency.TFT LCD Display
For a single 1.5 V battery white LED driver circuit, using the single-gate Schmitt inverter. Schmitt trigger output high pulse duration 3μs, can lead to a peak inductor current of about 65 mA, and bring the white LED high brightness white. Even if the battery voltage to 500mV, corresponding to the 33 mA peak current can still make white LED is bright enough white. Voltage of only 650mV at room temperature, this test circuit can be started.
Thus, according to the different sizes of LCD and the battery voltage should take a different white LED driver circuit. This is the most energy-efficient and most efficient drive circuit.