MAX17122 升压/降压型调节器、栅极驱动电荷泵、boo

MAX17122 升压/降压型调节器、栅极驱动电荷泵、boost-buck调节器，用于TV TFT LCD显示器

概述

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 gatedriver 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 package and operates over the -40°C to +85°C temperature range.

关键特性

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

应用/使用

LCD TV板

降压用于显示器栅极电荷

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