MAX1661

19-1356; Rev 0; 4/98 Active-Matrix Liquid Crystal Display (AMLCD) Supply ________________General Description The MAX1664 integrates power-supply and backplane drive circuitry for active-matrix thin-film-transistor (TFT) liquid crystal displays. Included are a single-output, pulsewidth-modulation boost converter (0.25 Ω switch), a dual-output (positive and negative) gate-driver supply using one inductor, an LCD backplane driver, and a simple phase-locked loop to synchronize all three outputs. High switching frequency (1MHz nominal) and phaselocked operation allow the use of small, minimumheight external components while maintaining low output noise. A +2.8V to +5.5V input voltage range allows operation with any logic supply. Output voltages are adjustable to +5.5V (DC-DC 1) and to +28V and -10V (DC-DC 2). The negative output voltage can be adjusted to -20V with additional components. Also included are a logic-level shutdown and a “Ready” output (RDY) that signals when all three outputs are in regulation. The boost-converter operating frequency can be set at 16, 24, or 32 times the backplane clock. This flexibility allows a high DC-DC converter frequency to be used with LCD backplane clock rates ranging from 20kHz to 72kHz. The MAX1664 is supplied in a 1.1mm-high TSSOP package. ____________________________Features o Integrates All Active Circuitry for Three DC-DC Converters o Ultra-Small External Components (ceramic capacitors, 2µH to 5µH inductors) o DC-DC Converters Phase-L...