SUPERTEX HV9985三路RGB LED驱动方案

SUPERTEX 公司的确HV9985是三路峰值电流模式PWM控制器,能用来驱动RGB LED或多路白光LED. HV9985具有40V线性稳压器,提供5V电源给IC供电,三个转换器的开关频率由外时钟信号或内部振荡器控制.三路有120度的相位差,以降低输入电流波纹.LED串间电流精度为±2% ,线性和PWM调光,PWM调光比高达5000:1,输入电压10-40V,主要用在RGB背景光,升压,降压和SEPIC转换器,多串白光LED驱动应用.本文介绍了HV9985的主要特性,方框图,典型应用电路以及PCB布局指南.

The HV9985 is a three-channel peak current mode PWM controller for driving single switch converters in a constant output current mode. It can be used for driving either RGB LEDs or multiple channels of white LEDs.

The HV9985 features a 40V linear regulator, which provides a 5.0V supply to power the IC. The switching frequencies of the three converters in the IC are controlled either with an external clock signal (the channels operate at a switching frequency of 1/12th of the external clock frequency) or using the internal oscillator. The three channels are positioned 120°out-of-phase to reduce the input current ripple. Each converter is driven by a peak current mode controller with output current feedback.

The three output currents can be individually dimmed using either linear or PWM dimming. The IC also includes three disconnect FET drivers which enable high PWM dimming ratios and also helps to disconnect the input in case of an output short circuit condition. The HV9985 includes hiccup mode protection for both open LED and short circuit condition to prevent the IC from shutting down in the case of intermittent faults.

HV9985主要特性:

Switch mode controller for single-switch converters Gate drivers optimized for driving Logic Level FETs

0.25A sourcing

0.5A sinking

Typical ±2% absolute and string-to-string current accuracy (with ±1% sense resistors)High PWM dimming ratio up to 5000:1

10-40V input range

Constant frequency operation up to 1.0MHz

On-chip clock or external clock option

Programmable slope compensation

Linear and PWM dimming

Output short circuit protection

Output over voltage protection

Hiccup mode protection

HV9985应用:

RGB backlight applications

Boost, buck & SEPIC topologies

Multiple string white LED driver applications



图1.HV9985内部方框图



图2.HV9985典型应用电路



图3.HV9985 PCB布局指南