TRIPLE-OUTPUT TFT LCD POWER SUPPLY WITH FAULT PROTECTION
SUNNYVALE, CA-August 14, 2002-Maxim Integrated Products introduces the MAX1889, which provides three regulated output voltages for active matrix, thin-film transistor liquid crystal displays (TFT LCDs). The MAX1889 combines a high-performance step-up regulator with two linear-regulator controllers and multiple levels of protection circuitry for a complete power-supply system.
The main DC-DC converter is a high-frequency (500kHz/1MHz) current-mode step-up regulator with an integrated N-channel power MOSFET that allows the use of ultra-small inductors and ceramic capacitors. With the high-frequency, closed-loop bandwidth performance, it provides fast transient response to pulsed loads while operating with efficiencies over 85%. The positive and negative linear-regulator controllers post-regulate charge-pump outputs for TFT gate-on and gate-off supplies.
The MAX1889 has a unique input switch control that can replace the typical input fuse by disconnecting the load from the input supply when a fault is detected. The fault detector monitors all three regulated output voltages and can monitor current from the input supply as well. In addition, the MAX1889 enters thermal shutdown when its overtemperature threshold is reached.
The MAX1889 undervoltage lockout (UVLO) is set at 2.5V to allow the input supply to droop under pulsed load conditions while avoiding any unexpected behavior when its input voltage dips below 2.5V momentarily. Also, built-in soft-start and cycle-by-cycle current limiting prevent input surge currents during input power cycling.
The MAX1889 is available in a 16-pin QFN package with a maximum thickness of 1mm for ultra-thin LCD panel designs. Prices start at $3.21 (1000-up, FOB USA).
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