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.
Key Features
Applications/Uses
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
LCD Modules
LCD Panels
Key Specifications:
Switch-Mode DC-DC Power Supplies
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