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OLED power driver ups image quality in small displays

Posted: 21 May 2008 ?? ?Print Version ?Bookmark and Share

Keywords:OLED power driver? active matrix OLED? AMOLED?


Texas Instruments Inc. has introduced an OLED power driver designed to enhance image quality for small form factor displays up to 2.5-inches. The TPS65136 power IC supports active-matrix OLED (AMOLED) displays used in mobile phones, digital cameras and portable media players.

AMOLED displays allow each pixel to emit its own light, resulting in high color saturation, thin form factor, high contrast ratio, fast response time and low power consumption. TI's TPS65136 manages power to AMOLED displays by providing positive and negative voltages, and supplying less current and lower voltages than passive matrix displays.

Unique converter technology
With just one 2.2?H inductor to generate both outputs on the single-inductor, multiple-output converter technology, the TPS65136 provides high picture quality and achieves a smaller solution size with a reduced component count. A buck-boost topology allows the device to generate a positive voltage up to 4.6V and adjustable negative output voltage down to -7V. In addition, the TPS65136 input voltage can be above or below the positive output voltage, allowing it to support new batteries with a starting voltage up to 4.8V.

The unique converter technology results in excellent line and load regulation, which is required to avoid potential display disturbances in mobile devices during transmit periods. The converter also lowers the switching frequency as the load current decreases to maintain high efficiency over the entire load current range. The TPS65136 maintains the switching frequency above the audible range with a voltage-controlled oscillator to avoid causing audible noise from the vibration of the ceramic output capacitors.

In addition to the TPS65136, TI provides a wide portfolio of OLED drivers. The TPS65130 and TPS65131 can efficiently power portable battery-powered equipment with a total efficiency of up to 89 percent. The devices' input voltage range of 2.7V to 5.5V allows the TPS65130/1 to be directly powered from Li-ion, three-celled NiMH/NiCd or alkaline batteries. This voltage, combined with the converters' minimum switching frequency of 1.25MHz, enables small power supply applications as the converters require only a few external components.

The TPS65136 and TPS65131 are available today in volume from TI and its authorized distributors. The TPS65136 is offered in a 16-pin QFN package, and the suggested resale price is $1.20 in 1,000-unit quantities. The TPS65131 is available in a small, 4mm x 4mm 24-pin QFN package at a suggested resale price starting at $3 in 1,000-unit quantities. The TPS65130 is available now through TI-authorized distributors and also comes in a small, 4mm x 4mm 24-pin QFN package, with a suggested resale price of $2.30 in 1,000-unit quantities.

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