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OLED power supply specifications
China LED lighting lighting network of technical papers
Generally small size of the OLED requires a positive voltage (Vdd) and a set of negative voltage (Vss) power, the power structure can be divided into two kinds of digital cameras and mobile architecture. Digital camera specifications: Vdd voltage range of 3V to 6V, Vss voltage range of-7V to-10V; phone power specifications are: Vdd voltage is approximately 2.5V, Vss voltage range of-7V to-10V. The input power of the two products is usually a lithium battery, the voltage range of approximately 3V to 4.2V.
China LED lighting lighting network of technical papers
Digital Camera Solution Vdd
China LED lighting lighting network of technical papers
As Vdd voltage range 3V to 6V, so the Vdd power structure should be the Buck / Boost or Boost. If we can not find a Buck / Boost power structure, but also very common use of Buck architecture, its designed to Buck / Boost structure, using a set of common buck power control IC, as long as the external MOSFET and an output of a diode can be designed to Buck / Boost output, shown in Fig. The working principle of this regulator is that when Lx is high voltage, the inductor current in accordance with the Vin / L increased the slope; Lx is low voltage, the inductor current will be in accordance with (Vout + VD) / L reduced the slope. Intermittent input and output current, which allows the output voltage higher or lower than the input voltage.
China LED lighting lighting network of technical papers
China LED lighting lighting network of technical papers
Designers can also use a Buck / Boost Power Supply IC produce the desired voltage output, Figure II is a direct boost / buck converter IC. It combines a step-up converter and linear regulator, providing both step-up, or you can step-down conversion program. The converter input voltage above or below the output voltage can provide a stable output, allowing the input range: 1.8V to 11V, 3.3V or 5V can be preset for the output can also be obtained using the two divider resistors can be Adjustable output voltage: 1.25V to 5.5V, up to 85% efficiency. If you need the output between 3.5V to 4V, can boost converter and linear regulator is combined ways. Such as: MAX1606 MAX8512 boost converter and linear regulator combination.
China LED lighting lighting network of technical papers
China LED lighting lighting network of technical papers
From the perspective of cost, you can select charge pump, without the inductor and output diode, such as MAX1759 charge pump boost / buck structure, resulting in all the way to a stable output. Despite its frequency higher than 1.5MHz, can still maintain a low 50uA quiescent current.
Some designers in pursuit of higher efficiency, boost mode is selected to produce a stable output than input, as shown in step three of the architecture. As is the external MOSFET power switch can provide higher output power. The output power conditions permit, you can select built-in MOSFET power switch of the boost converter, such as MAX1722, which can effectively save space and reduce costs.
China LED lighting lighting network of technical papers
China LED lighting lighting network of technical papers
Vdd phone network technology solutions for China Lighting LED Lighting Articles
For phone Vdd, Buck can choose to provide the required voltage of the circuit. Figure Four is a built-in MOSFET synchronous buck power switch structure, providing 400mA of output current. Frequency up to 1.2MHz, allowing designers to use a small inductor and output capacitor, the efficiency as high as 90%.
China LED lighting lighting network of technical papers
Negative voltage Vss solution described above, if the designer could not find suitable temporary negative voltage output power supply IC, can also use the Buck power IC. As shown in Figure Five, suspended ground structure to generate negative voltage Vss, the principle is: the normal output connected to the input power from the converter to the negative pressure side to ensure a stable output, if you need different output voltage can be across the two resistors between the output and the FB, set the output voltage.
China LED lighting lighting network of technical papers
China LED lighting lighting network of technical papers
Can also choose a negative voltage output converter, Figure VI negative pressure is commonly used PWM converter, a small external components, the design simple, the work of the structure at a fixed frequency PWM little interference.
China LED lighting lighting network of technical papers
China LED lighting lighting network of technical papers
Conclusion
Although the OLED is an emerging technology industry, its specification is not very clear, but the power supply structure basically unchanged. iSuppli study shows that conversion from monochrome to color displays demand driven, OLED display market is expected to be in 2006, 10 billion dollar industry. OLED has a self-luminous, and other advantages as thin DSC, handheld game consoles or mobile phones and other products the ideal choice, these products are very promising. In short, the technology and market potential is a key factor in industry growth. Technically, the domestic OLED manufacturers are sure to have a considerable, if we can further enhance the brand, product positioning on the strength, will gradually take off the OLED industry in the standing position of excellence.
