Step-Up Regulator with Switch Control and Operational Amplifier for TFT LCD

The MAX8758 includes a high-performance step-up regulator, a high-speed operational amplifier, and a logic-controlled, high-voltage switch-control block with programmable delay. The device is optimized for thin-film transistor (TFT) liquid-crystal display (LCD) applications.

The step-up DC-DC regulator provides the regulated supply voltage for the panel source driver ICs. The converter is a high-frequency (640kHz/1.2MHz), current-mode regulator with an integrated 14V n-channel power MOSFET. The high-switching frequency allows the use of ultra-small inductors and ceramic capacitors. The current-mode control architecture provides fast transient response to pulsed loads. The regulator achieves efficiencies over 85% by bootstrapping the supply rail of the internal gate driver from the step-up regulator output. The step-up regulator features undervoltage lockout (UVLO), soft-start, and internal current limit. The high-current operational amplifier is designed to drive the LCD backplane (VCOM). The amplifier features high output current (±150mA), fast slew rate (7.5V/µs), wide bandwidth (12MHz), and rail-to-rail inputs and outputs.

The MAX8758 is available in a 24-pin, 4mm x 4mm, thin QFN package with a maximum thickness of 0.8mm for ultra-thin LCD panels. The device operates over the -40°C to +85°C temperature range.

Applications

* LCD Monitors * Notebook Displays

* 1.8V to 5.5V Input Voltage Range

* Input Undervoltage Lockout

* 0.5mA Quiescent Current

* 640kHz/1.2MHz Current-Mode Step-Up Regulator

* Fast Transient Response

* High-Accuracy Output Voltage (1.5%)

* Built-In 14V, 2.5A, 115mΩ MOSFET

* High Efficiency

* Programmable Soft-Start

* Current Limit with Lossless Sensing

* Timer-Delay Fault Latch

* High-Speed Operational Amplifier

* ±150mA Output Current

* 7.5V/µs Slew Rate

* 12MHz, -3dB Bandwidth

* Rail-to-Rail Inputs/Outputs

* Dual Mode™, Logic-Controlled, High-Voltage Switch with Programmable Delay

* Thermal-Overload Protection

* 24-Pin, 4mm x 4mm, Thin QFN Package