Internal-Switch Boost Regulator with Integrated Scan Driver, VCOM Calibrator, and Op Amp for TFT LCDs

The MAX17100 includes a high-voltage step-up regulator, three high-performance operational amplifiers, two linear regulators, two high-voltage switch control blocks for gate-driver supply modulation, a digital VCOM calibrator, and six independent scan drivers.

The DC-DC converter is a 1.2MHz current-mode stepup regulator with a built-in power MOSFET and provides the regulated supply voltage for the panel source driver ICs. The built-in power MOSFET allows output voltages to be as high as 18V from inputs of 2.5V to 6V. A built-in 7-bit digital soft-start function limits inrush currents during startup. The step-up regulator provides fast transient response to pulsed loads while producing efficiencies over 87%.

Three operational amplifiers, typically used as the gamma correction divider string, are configured as unity-gain buffers and feature high output short-circuit current (200mA), fast slew rate (45V/µs), and wide bandwidth (20MHz). Their rail-to-rail inputs and outputs maximize application flexibility.

Two linear regulators provide regulated gate-on and gate-off supplies for TFT panel. The two high-voltage switch control blocks modulate the shape of the gate-on supply with adjustable startup delay.

One operational amplifier is designed to drive the LCD backplane (VCOM). It features high short-circuit current of 200mA. The programmable VCOM calibrator adjusts the VCOM output-voltage level through serial interface by sinking a programmable current from the VCOM resistor-divider. The calibrator includes nonvolatile memory cells that store the desired VCOM voltage level.

The six independent high-voltage level-shifting scan drivers are designed to drive the TFT panel gate lines. The outputs swing from +35V (maximum) to -15V (minimum) and can swiftly drive capacitive loads.

The MAX17100 is available in a lead-free, 48-pin, thin QFN package with 0.4mm lead spacing. The package is a 6mm x 6mm square with a maximum thickness of 0.8mm for ultra-thin LCD panel design.

Applications

* LCD Monitors * LCD TVs

* 2.5V to 6V Input Supply Range

* 1.2MHz Current-Mode Step-Up Converter

* Fast Transient Response to Pulsed Load

* High-Accuracy Output Voltage (1%)

* Built-In 20V, 3A, 0.16Ω n-Channel Power MOSFET

* Cycle-by-Cycle Current Limit

* High Efficiency (87%)

* Three High-Performance Operational Amplifiers

* 200mA Output Short-Circuit Current

* 45V/µs Slew Rate

* 20MHz, -3dB Bandwidth

* Rail-to-Rail Inputs and Outputs

* Linear Regulator for Gate-On and Gate-Off Supply

* Two Logic-Controlled High-Voltage Switches with Adjustable Delay

* Programmable VCOM Calibrator

* 7-Bit Adjustable Current-Sink Output

* Serial Interface

* Nonvolatile Setting Memory

* Six Independent Level-Shifting Scan Drivers

* Built-In Sequencing

* Soft-Start and Timer-Delayed Fault Latch for All Regulator Outputs

* Thermal-Overload Protection

* Gate Driver for External Input-Side Series MOSFET