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Step-Up, Step-Down Regulator, Gate-On Charge Pump, and Boost-Buck Regulator for TV TFT LCD Display

High-Performance Integrated IC for LCD HDTV Power Supply Provides High Efficiency and Minimizes External Components

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • 8V to 16.5V Operating Range
  • 750kHz Switching Frequency
  • 22V Internal-Switch High-Performance Step-Up Regulator
    • Fast Load-Transient Response
    • Current-Mode PWM Operation
    • 100mΩ, 3.9A nMOS Switch
    • Capacitor-Adjustable Soft-Start
    • High-Voltage Stress Function
    • Drives External pMOS Shutdown Switch
  • 22V Internal-Switch Step-Down Regulator
    • Preset 1% Accurate 3.3V Output Voltage or Adjustable Output (Dual Mode™)
    • Current-Mode PWM Operation
    • 200mΩ, 2.5A nMOS Switch
    • Capacitor-Adjustable Power-Good Output
  • 36V Internal-Switch Boost-Buck Regulator
    • Temperature-Compensated Output
    • Programmable Fixed Levels with Temperature-Controlled Transition
    • Current-Mode PWM Operation
    • 200mΩ, 1.8A pMOS Switch
  • Positive Charge-Pump Linear Regulator Controller
    • Adjustable 1% Accurate Output Voltage
    • Uses External pnp Transistor
    • Regulates Switching-Node-Driven Charge-Pump Doubler
    • Power-Good Output
  • Negative Linear Regulator Controller
    • Adjustable 1.5% Accurate Output Voltage
    • Uses External npn Transistor
  • Soft-Start for All Outputs
  • Adjustable Power-Up Sequence
  • Timed-Output Fault Protection with Restart for All Outputs
  • Latched Thermal-Shutdown Protection
  • 40-Pin, 6mm x 6mm Thin QFN Package

Applications/Uses

  • LCD TV Panels

Description

The MAX17122 multiple-output power-supply IC generates all the supply rails for thin-film transistor (TFT) liquid-crystal display (LCD) TV panels. It can operate from 8V to 16.5V input voltages and is optimized for LCD TV panel applications running directly from 12V regulated supplies. It includes a 22V internal-switch step-down regulator for digital logic, a 22V internal switch step-up regulator to power the TFT source drivers, and a temperature-compensated 36V internal-switch boost-buck regulator that produces a negative output that can vary according to the temperature sensed by an external NTC thermistor. All three of these regulators feature high-efficiency and fixed-frequency operation. High-frequency operation allows the use of small inductors and capacitors, resulting in a compact solution.

The MAX17122 includes a positive charge-pump linear regulator controller that uses an external pnp bipolar junction transistor (BJT) to typically form a regulated charge-pump doubler to supply the LCD positive gate-driver supply voltage. A negative gate-driver supply is derived linearly between the boost-buck regulator's output and ground, using an external npn BJT connected to ground and a small bypass capacitor.

Other features include an external-capacitor-timed, open-drain, power-good output that monitors the step-down regulator's feedback and a simple untimed output that monitors the positive charge-pump linear regulator's feedback. A high-voltage stress function is available for the step-up regulator output. The GATE output directly drives an external p-channel MOSFET to provide True Shutdown™ of the step-up output.

The MAX17122 is available in a 6mm x 6mm, 40-pin thin QFN lead-free package and operates over the -40°C to +85°C temperature range.

Simplified Block Diagram

MAX17122: Typical Operating Circuit MAX17122: 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 .