Linear LT3492三输出恒流源LED驱动方案

Linear 公司的LT3492是三输出DC/DC转换器,可用作恒流源LED驱动器,可工作在降压,升压和降升压模式. True Color PWM™调光的调光比高达3000:1,可调频率从330kHz 到2.1MHz,工作电压从3V 到30V,瞬间保护到40V,主要用于RGB照明,大显示屏,汽车和航空照明以及恒流源.本文介绍LT3492主要特性,方框图,以及多种应用电路图.

The LTR3492 is a triple output DC/DC converter designed to operate as a constant-current source and is ideal for driving LEDs. The LT3492 works in buck, boost or buckboost mode. The LT3492 uses a fixed frequency, current mode architecture resulting in stable operation over a wide range of supply and output voltages. A frequency adjust pin allows the user to program switching frequency between 330kHz and 2.1MHz to optimize efficiency and external component size.

The external PWM input provides 3000:1 LED dimming on each channel. Each of the three channels has a built-in gate driver to drive an external LED-disconnect P-channel MOSFET, allowing high dimming range. The output current range of each channel of the LT3492 is programmed with an external sense resistor.

The CTRL pin is used to adjust the LED current either for analog dimming or overtemperature protection.

LT3492主要特性:

True Color PWM™ Dimming Delivers Up to 3000:1 Dimming Ratio

Built-In Gate Driver for PMOS LED Disconnect

Three Independent Driver Channels with 600mA, 60V Internal Switches

Operates in Buck, Boost, Buck-Boost Modes

CTRL Pin Accurately Sets LED Current Sense Threshold Over a Range of 10mV to 100mV

Adjustable Frequency: 330kHz to 2.1MHz

Open LED Protection

Wide Input Voltage Range:

Operation from 3V to 30V

Transient Protection to 40V

Surface Mount Components

28-Lead (4mmx 5mm) QFN and TSSOP Packages

LT3492应用:

RGB Lighting

Billboards and Large Displays

Automotive and Avionic Lighting

Constant-Current Sources

图1.LT3492方框图:升压配置

图2.高调光比三输出降压模式LED电源

图3.最低BOM的降压模式LED驱动器


图4.三路升压,100mAx12 LED驱动器


图5. 双路升压LED驱动器

图6.三路升压,100mAx9 LED驱动器:Vin控制调光


图7.三路升压,100mAx12 LED驱动器



图8.三路降模式LED驱动器:开路LED保护