Active Matrix Liquid Crystal Display (AMLCD) Supply

The MAX1664 integrates power-supply and backplane drive circuitry for active-matrix thin-film-transistor (TFT) liquid crystal displays. Included are a single-output, pulse-width-modulation boost converter (0.25Ω 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 phase-locked operation allow the use of small, minimum-height 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.

Applications

* LCD Modules * LCD Panels

* Integrates All Active Circuitry for Three DC-DC Converters

* Ultra-Small External Components (ceramic capacitors, 2µH to 5µH inductors)

* DC-DC Converters Phase-Locked to Backplane Frequency for Lowest Noise

* Low Operating Voltage (down to +2.8V)

* Adjustable Output Voltage from VIN to +5.5V

* Load Currents Up to 500mA

* Adjustable TFT Gate Driver Output:

* Positive, VIN to +28V

* Negative, 0 to -10V (-20V with added components)

* Includes 0.35Ω Backplane Driver

* 1µA Shutdown Current

* Power-Ready Output Signal