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Multi-Output Power Supply with VCOM Amplifier and High-Voltage Gamma Reference for LCD TVs

Highly Integrated LCD TV Power Supply with Gamma Reference and VCOM Op Amp Minimizes Space and Cost

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • 8.0V to 16.5V IN Supply-Voltage Range
  • Selectable Frequency (500kHz/750kHz)
  • Current-Mode Step-Up Regulator
    • Fast Load-Transient Response
    • High-Accuracy Output Voltage (1.0%)
    • Built-In 20V, 3.5A, 100mΩ MOSFET
    • High Efficiency
    • Adjustable Soft-Start
    • Adjustable Current Limit
    • Low Duty-Cycle Operation (13.2VIN - 13.5V AVDD)
  • Current-Mode Step-Down Regulator
    • Fast Load-Transient Response
    • Built-In 20V, 3.2A, 120mΩ MOSFET
    • High Efficiency
    • 3ms Internal Soft-Start
  • Adjustable Positive Charge-Pump Regulator
  • Adjustable Negative Charge-Pump Regulator
  • Integrated High-Voltage Switch with Adjustable Turn-On Delay
  • High-Speed Operational Amplifier
    • ±200mA Short-Circuit Current
    • 45V/µs Slew Rate
  • High-Accuracy Reference for Gamma Buffer
    • ±0.5% Feedback Voltage
    • Up to 30mA Load Current
    • Low-Dropout Voltage 0.5V at 60mA
  • External p-Channel Gate Control for AVDD Sequencing
  • XAO Comparator
  • Input Undervoltage-Lockout and Thermal-Overload Protection
  • 48-Pin, 7mm x 7mm, Thin QFN Package

Applications/Uses

  • LCD TV Panels

Description

The MAX17114 generates all the supply rails for thin-film transistor liquid-crystal display (TFT LCD) TV panels operating from a regulated 12V input. It includes a step-down and a step-up regulator, a positive and a negative charge pump, an operational amplifier, a high-accuracy, high-voltage gamma reference, and a high-voltage switch control block. The MAX17114 can operate from input voltages from 8V to 16.5V and is optimized for an LCD TV panel running directly from 12V supplies.

The step-up and step-down switching regulators feature internal power MOSFETs and high-frequency operation allowing the use of small inductors and capacitors, resulting in a compact solution. The step-up regulator provides TFT source driver supply voltage, while the step-down regulator provides the system with logic supply voltage. Both regulators use fixed-frequency current-mode control architectures, providing fast load-transient response and easy compensation. A current-limit function for internal switches and output-fault shutdown protects the step-up and step-down power supplies against fault conditions. The MAX17114 provides soft-start functions to limit inrush current during startup. In addition, the MAX17114 integrates a control block that can drive an external p-channel MOSFET to sequence power to source drivers.

The positive and negative charge-pump regulators provide TFT gate-driver supply voltages. Both output voltages can be adjusted with external resistive voltage-dividers. A logic-controlled, high-voltage switch block allows the manipulation of the positive gate-driver supply. The MAX17114 includes one high-current operational amplifier designed to drive the LCD backplane (VCOM). The amplifier features high output current (±200mA), fast slew rate (45V/µs), wide bandwidth (20MHz), and rail-to-rail outputs.

Also featured in the MAX17114 is a high-accuracy, high-voltage adjustable reference for gamma correction.

The MAX17114 is available in a small (7mm x 7mm), ultra-thin (0.8mm), 48-pin, TQFN-EP package and operates over the -40°C to +85°C temperature range.

Simplified Block Diagram

MAX17114: Typical Operating Circuit MAX17114: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .