Power Electronics

DC-DC Converter for TFT LCDs Includes High-current Op Amps

Maxim Integrated Products has introduced the MAX1518B, a fully integrated, step-up dc-dc converter for active-matrix thin-film transistor (TFT) liquid-crystal displays (LCDs). The MAX1518B includes a high-performance step-up regulator, two linear regulator controllers and five high-current operational amplifiers. Also integrated is a logic-controlled, high-voltage switch with adjustable delay.

The five op amps can drive the LCD backplane (VCOM) and the gamma-correction-divider string simultaneously. They feature a ±150-mA output current, a slew rate of 13 V/µs, a bandwidth of 12 MHz, and rail-to-rail inputs and outputs. The MAX1518B provides the regulated supply voltage for the panel source driver ICs. As a 1.2-MHz current-mode regulator, the MAX1518B integrates a 14-V n-channel MOSFET that allows the use of ultrasmall inductors and ceramic capacitors. It provides fast transient response to pulsed loads while achieving efficiencies over 85%. The two integrated, gate-on and gate-off linear-regulator controllers provide regulated TFT gate-on and gate-off supplies using external charge pumps attached to the switching node.

The MAX1518B is available in a 5-mm × 5-mm × 0.8-mm 32-pin thin QFN package. Prices start at $3.90 for 1000-unit quantities.

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