Semtech SC5010超薄筆記本相移式8通道白光LED背光驅動方案

Semtech(升特)公司的 SC5010是超薄筆記本面板用的相移式8通道白光LED背光驅動器,采用創新的PWM相移調光控制法,可使用1mm高的2.2μH微型電感，用于高效超薄的4mm厚度顯示器.SC5010提供精確的背光色溫以及全屏一致的亮度，通道間的電流匹配度為+/-1%，精度為+/-1.5%。它有完備的保護功能，包括led開路保護和可編程的LED短路保護、可調過壓保護（OVP），以及過熱保護；另外還有欠壓鎖定（UVLO）關斷功能。器件輸入電4.5V至27V；輸出電壓最高達50V, 最高效率達92%,最多可驅動112只白光LED,主要用在超薄筆記本電腦,UMPC,LCD監視器和平板電腦.本文介紹了SC5010主要特性,方框圖,LED PWM調光控制框圖,詳細應用電路以及SEPIC配置圖,高輸出電壓應用電路圖.

The SC5010 is an 8-channEL high-precision, high-effi ciency step-up (Boost) LED driver for backlight applications. It features wide input voltage range (4.5V to 27V) , fl exible output configuration, wide analog and PWM dimming range, phase shifting and fading. It also features video signal synchronization (VSYNC), I2C interface, and numerous protection features. An optional disconnect p-MOSFET provides true load disconnection and inrush current limiting.

The boost controller, with programmable switching frequency from 200kHz to 2.2MHz, maximizes effi ciency by dynamically minimizing the output voltage while maintaining LED string current accuracy. It provides excellent line and load response with no external compensation components.

Each linear current sink is matched within ±1% for superb lighting uniformity, and the accuracy of each string current is ±1.5%. An external resistor adjusts the current from 10-30mA per string. It also features PWM dimming resolution of 9 or 10 bits (user selectable) over dimming frequency from 100Hz to 20kHz, synchronized to the SYNC signal or the boost oscillator. String-by-string phase shifting reduces the demand on the input/output capacitance, decreases EMI, and improves dimming linearity.

SC5010 is available in a low-profi le, thermally enhanced, 4 X 4 X 0.6(mm) QFN 28-pin package.

SC5010主要特性:

VIN Range — 4.5V to 27V, VOUT Range — Up to 50V

Step-up (Boost) Controller

Excellent Transient Response

Programmable Switching Frequency

Linear Current Sinks

8 Strings, up to 30mA/String

Current Matching ±1%

Current Accuracy ±1.5%

PWM Dimming

String-by-String Phase Shifting

Input Dimming Frequency 100Hz-30kHz

User Selectable 9 or 10 Bits Dimming Resolution

Optional Synchronization to VSYNC/HSYNC Signal

5-bit Analog Dimming

Optional External p-MOSFET Disconnect Switch

True Load Disconnect and Inrush Current Limiting

I2C Interface

Fault Status — Open/Short LED, UVLO, OTP

Device Control — SYNC Freq, PLL Setting

Protection Features

Open/Shorted LED(s) and adjustable OVP

Over-Temperature and UVLO Shutdown Protection

4 X 4(mm) 28-pin QFN Package

SC5010應用:

Notebook PCs, UMPC, LCD Monitors, and Tablet PCs

圖1.SC5010方框圖


圖2.SC5010 LED PWM調光控制框圖

圖3.SC5010典型應用電路圖

圖4.SC5010詳細的應用電路圖

圖5.SC5010 SEPIC配置圖

圖6.SC5010高輸出電壓應用電路圖