MAX17126 Multi-Output Power Su

MAX17126 Multi-Output Power Supply with VCOM Amplifier and High-Voltage Gamma Reference for LCD TVs

The MAX17126 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 MAX17126 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 MAX17126 provides soft-start functions to limit inrush current during startup. In addition, the MAX17126 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 MAX17126 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.

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, 4.2A, 100mΩ MOSFET
• High Efficiency
• Adjustable Soft-Start
• Adjustable Current Limit
• Low Duty-Cycle Operation (13.2V_IN - 13.5V AVDD)

Current-Mode Step-Down Regulator

• Fast Load-Transient Response
• Built-In 20V, 3.2A, 100mΩ 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

• ±1% Feedback Voltage
• Up to 30mA Load Current
• Low-Dropout Voltage 0.5V at 60mA

External p-Channel Gate Control for AVDD Sequencing

PGOOD Comparator

Input Undervoltage Lockout and Thermal-Overload Protection

48-Pin, 7mm x 7mm, Thin QFN Package

Applications/Uses

LCD TV Panels

PowerSuAmplifierOutputMultiVCOM

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