First to Market with Boost Converter and Buffers Integrated on One Chip
National Semiconductor enhanced its position in the burgeoning displays market by introducing three boost converters with integrated buffers that are ideal for generating bias supplies for large-format, thin-film-transistor liquid-crystal displays (TFT LCDs).
Based on National's successful LM2622 boost converter, the LM2702, LM2710 and LM2711 include the VCOM buffer, Gamma buffers and other circuitry that support soft start, power supply sequencing and other features. This level of integration is an industry first for the notebook PC and flat panel monitor TFT LCD markets. It reduces component count and required board space, allowing manufacturers to develop thinner, lighter panels with larger viewing area.
The highly efficient current mode PWM boost converter is the core of all three of the new devices. The LM2702 features two integrated buffers: one VCOM buffer and one Gamma buffer. The LM2702 operates from an input supply voltage in the 2.2V to 12V range and is available in a TSS0P-16 package.
The LM2710 features five integrated buffers: one VCOM buffer and four Gamma buffers, or, alternately, five Gamma buffers. The LM2711 features four integrated buffers: one VCOM buffer and three Gamma buffers, or, alternately, four Gamma buffers. Both devices operate from an input supply voltage in the 2.2V to 7.5V range and are available in a TSS0P-20 package.
All three devices feature integrated patented soft-start circuitry that limits the startup inrush current of the boost converter without the need for external components. The soft-start circuitry supports tailoring of startup timing via a soft-start pin.
Pricing and Availability
On the market today, the boost converters are affordably priced. In quantities of 1000 pieces, the LM2702 is $1.40 apiece; the LM2710 is $2.00 apiece; and the LM2711 is $1.80 each.
