TFT-LCD DC-DC Converters with Operational Amplifiers

The MAX1516/MAX1517/MAX1518 include a high-performance step-up regulator, two linear-regulator controllers, and high-current operational amplifiers for active-matrix thin-film transistor (TFT) liquid-crystal displays (LCDs). Also included is a logic-controlled, high-voltage switch with adjustable delay.

The step-up DC-DC converter provides the regulated supply voltage for the panel source driver ICs. The converter is a high-frequency (1.2MHz) current-mode regulator with an integrated 14V n-channel MOSFET that allows the use of ultra-small inductors and ceramic capacitors. It provides fast transient response to pulsed loads while achieving efficiencies over 85%.

The 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 MAX1518 includes five high-performance operational amplifiers, the MAX1517 includes three, and the MAX1516 includes one operational amplifier. These amplifiers are designed to drive the LCD backplane (VCOM) and/or the gamma-correction divider string. The devices feature high output current (±150mA), fast slew rate (13V/µs), wide bandwidth (12MHz), and rail-to-rail inputs and outputs.

The MAX1516/MAX1517/MAX1518 are available in 32-pin thin QFN packages with a maximum thickness of 0.8mm for ultra-thin LCD panels.

Applications

* Automotive Displays * LCD Monitor Panels * Notebook Computer Displays

* 2.6V to 5.5V Input Supply Range

* 1.2MHz Current-Mode Step-Up Regulator

* Fast Transient Response to Pulsed Load

* High-Accuracy Output Voltage (1.5%)

* Built-In 14V, 2.4A, 0.16Ω n-Channel MOSFET

* High Efficiency (90%)

* Linear-Regulator Controllers for VGON and VGOFF

* High-Performance Operational Amplifiers

* ±150mA Output Short-Circuit Current

* 13V/µs Slew Rate

* 12MHz, -3dB Bandwidth

* Rail-to-Rail Inputs/Outputs

* Logic-Controlled, High-Voltage Switch with Adjustable Delay

* Timer-Delay Fault Latch for All Regulator Outputs

* Thermal-Overload Protection

* 0.6mA Quiescent Current