基于MAX17014的低成本LCD TV電源解決方案

Maxim 公司的MAX17014是低成本多輸出的LCD TV電源控制器，能從12V中產(chǎn)生TFT-LCD TV和監(jiān)視器中所需要的電壓，包括降壓和升壓穩(wěn)壓器，正和負(fù)電荷泵，兩個(gè)運(yùn)算放大器，以及Dual Mode邏輯控制高壓控制區(qū)塊。MAX17014輸入電壓從8V到16。5V，可調(diào)整的輸出電壓低到1.25V，精度1%，內(nèi)置20V/3.3A的110毫歐姆的N-MOSFET，主要用于LCD TV屏和LCD監(jiān)視器屏。本文介紹MAX17014主要特性，方框圖，正和負(fù)電荷泵穩(wěn)壓器方框圖，簡化工作電路圖以及典型工作電路圖和所用的元件列表。

MAX17014：Low-Cost Multiple-Output Power Supply for LCD TVs

The MAX17014 multiple-output power-supply controller generates all the supply rails for thin-film transistor (TFT) liquid-crystal display (LCD) panels in TVs and monitors operating from a regulated 12V input. It includes a step-down and a step-up regulator, a positive and a negative charge pump, two operational amplifiers, and a Dual Mode? logic-controlled highvoltage switch control block. The MAX17014 can operate from 8V to 16.5V input voltages and is optimized for LCD TV panel and LCD monitor applications running directly from 12V supplies.

The step-up and step-down regulators feature internal power MOSFETs and high-frequency operation allowing the use of small inductors and capacitors, resulting in a compact solution. Both switching 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 protect the step-up and step-down power supplies against fault conditions. The MAX17014 provides soft-start functions to limit inrush current during startup. The MAX17014 provides adjustable power-up timing.

The positive and negative charge-pump regulators provide TFT gate driver supply voltages. Both output voltages can be adjusted with external resistive voltage-dividers. The switch control block allows the manipulation of the positive TFT gate driver voltage.

The MAX17014 includes two high-current operational amplifiers designed to drive the LCD backplane (VCOM). The amplifier features high output current (±150mA), fast slew rate (100V/μs), wide bandwidth (20MHz), and rail-to-rail inputs and outputs. A series p-channel MOSFET is integrated to sequence power to AVDD after the MAX17014 has proceeded through normal startup, and provides True Shutdown?.

The MAX17014 is available in a small (7mm x 7mm), low-profile (0.8mm), 48-pin thin QFN package and operates over a -40℃ to +85℃ temperature range.

MAX17014主要特性：

_ Optimized for 10.8V to 13.2V Input Supply

_ 8V to 16.5V Input Supply Range

_ Selectable Frequency (600kHz/1.2MHz)

_ Current-Mode Step-Up Regulator

Built-In 20V, 3.3A, 110mohm ?n-Channel MOSFET

High-Accuracy Output Voltage (1%)

True Shutdown

Fast Load-Transient Response

High Efficiency

3ms Internal Soft-Start

_ Current-Mode Step-Down Regulator

Built-In 20V, 2.5A, 120m n-Channel MOSFET

Fast Load-Transient Response

Adjustable Output Voltage Down to 1.25V

Skip Mode at Light Load

High Efficiency

3ms Internal Soft-Start

_ Adjustable Positive and Negative Charge-Pump Regulators

_ Soft-Start and Timer-Delay Fault Latch for All Outputs

_ Logic-Controlled High-Voltage Integrated Switches with Adjustable Delay

_ Two High-Speed Operational Amplifiers

±150mA Short-Circuit Current

100V/μs Slew Rate

20MHz, -3dB Bandwidth

_ 120m p-Channel FET for AVDD Sequencing

_ Input Undervoltage Lockout and Thermal-Overload Protection

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

MAX17014應(yīng)用：

LCD TV Panels

LCD Monitor Panels


圖1。MAX17014功能方框圖

圖2。MAX17014正電荷泵穩(wěn)壓器方框圖

圖3。MAX17014負(fù)電荷泵穩(wěn)壓器方框圖

圖4。MAX17014的開關(guān)控制方框圖

MAX17014 is a complete power-supply system for TFT-LCD panels in monitors and TVs. The circuit generates論a +3.3V logic supply, a +16V source driver supply, a +34.5V positive gate driver supply, and a -6V negative gate driver supply from a 12V ±10% input supply.


圖5。MAX17014典型工作電路圖

典型工作電路圖中的元件列表：


圖6。MAX17014簡化工作電路圖