MAX1542

TFT LCD DC-to-DC Converter with Operational Amplifiers

TFT LCD DC-DC Converters Include a High-Performance Boost Regulator and Two High-Current Operational Amplifiers for Active-Matrix, Thin-Film Transistor (TFT), Liquid-Crystal Displays (LCDs)

Data Sheet (Rev. 0)

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Overview

Ultra-High-Performance Step-Up Regulator
- Fast Transient Response to Pulsed Load Using Current-Mode Control Architecture
- High-Accuracy Output Voltage (1.3%)
- Built-In 14V, 1.2A, 0.2Ω N-Channel Power MOSFET with Lossless Current-Sensing
- High Efficiency (85%)
- 8-Step Current-Controlled Digital Soft-Start
Two High-Performance Operational Amplifiers
- 150mA Output Short-Circuit Current
- 7.5V/µs Slew Rate
- 12MHz -3dB Bandwidth
- Rail-to-Rail Inputs/Outputs
- Unity Gain Stable
Logic-Controlled High-Voltage Switch with Adjustable Delay
Timer Delay Latch FB Fault Protection
Thermal Protection
2.6V to 5.5V Input Operating Voltage Range
3.6mA (Switching), 0.45mA (Not Switching) Quiescent Current
Ultra-Thin 20-Pin Thin QFN Package (5mm x 5mm x 0.8mm)

The MAX1542/MAX1543 include a high-performance boost regulator and two 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 MAX1543 includes an additional high-voltage load switch and features pin-selectable boost regulator switching frequency.

The step-up DC-to-DC converter is a high-frequency 640kHz (MAX1543)/1.2MHz (MAX1542/MAX1543) current-mode regulator with a built-in power MOSFET that allows the use of ultra-small inductors and ceramic capacitors. It provides fast transient response to pulsed loads while producing efficiencies over 85%.

The two easy-to-use, high-performance operational amplifiers can drive the LCD backplane (VCOM) and/or the gamma correction divider string. The devices feature high short-circuit current (150mA), fast slew rate (7.5V/µs), wide bandwidth (12MHz), and rail-to-rail inputs and outputs.

The MAX1542/MAX1543 are available in 20-pin thin QFN packages with a maximum thickness of 0.8mm for ultra-thin LCD panel design.

Applications

Car-Navigation Displays
LCD Monitor Panels
Notebook Computer Displays
PDAs

Documentation

Data Sheet 1

MAX1542-MAX1543: TFT LCD DC-to-DC Converter with Operational Amplifiers Data Sheet (Rev.0) 06/03/2003

Reliability Data 1

MAX1542 Reliability Data 01/12/2023

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Evaluation Kits

Evaluation Kit for the MAX1542, MAX1543

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Features and Benefits

+2.6V to +5.5V Input Range
Output Voltages
- +8V Output at 300mA (3V Input Step-Up
- Switching Regulator)
- +22V Output at 20mA (Positive Charge Pump)
- -7V Output at 20mA (Negative Charge Pump)
- +4V Output at ±150mA (Operational Amplifiers VOUT1 and VOUT2)
Resistor-Adjustable Switching Regulator and Op-Amp Output Voltages
Logic-Controlled, High-Voltage Switch with Adjustable Delay
Greater than 85% Efficiency (Step-Up Switching Regulator)
Selectable 600kHz/1.2MHz Step-Up Switching Frequency
Low-Profile Surface-Mount Components
Also Evaluates the MAX1542 (IC Replacement Required)
Fully Assembled and Tested

Product Details

The MAX1543 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that provides the voltages and features required for active-matrix, thin-film transistor (TFT) liquid-crystal displays (LCDs). The EV kit contains a step-up switching regulator, a positive two-stage charge pump for the TFT gate-on supply, and a negative single-stage charge pump for the TFT gate-off supply. Also included are two operational amplifiers that can be used to drive the LCD backplane (VCOM) or the gamma-correction divider string, and a logic-controlled, high-voltage switch with adjustable delay. The EV kit also evaluates the MAX1542 after IC replacement.

The EV kit operates from a DC supply voltage of +2.6V to +5.5V. The step-up switching regulator is configured for a +8V output providing at least 250mA. The positive charge pump is configured for a +22V output providing at least 20mA. The negative charge pump is configured for a -7V output providing at least 20mA. The two operational amplifiers are both configured for +4V, each capable of providing up to ±150mA peak. The high-voltage switch can be used to delay the startup of the positive charge pump's output. The delay time is set with an external capacitor.

The MAX1543 EV kit demonstrates low quiescent current and high efficiency (85%) for maximum battery life. Operation at 1.2MHz allows the use of tiny surface-mount components. The MAX1543 QFN package (0.8mm maximum height) with low-profile external com-ponents allows this circuit to be less than 1.25mm high.