LM3434主要特性 DLP投映仪RGB LED驱动器介绍

The LM3434 is an adapTIve constant on-TIme DC/DC buck (step-down) constant current controller (a true current source). The LM3434 provides a constant current for illuminaTIng high power LEDs. The output configuraTIon allows the anodes of multiple LEDs to be tied directly to the ground referenced chassis for maximum heat sink efficacy. The high frequency capable architecture allows the use of small external passive components and no output capacitor while maintaining low LED ripple current. Two control inputs are used to modulate LED brightness. An analog current control input is provided so the LM3434 can be adjusted to compensate for LED manufacturing variations and/or color temperature correction. The other input is a logic level PWM control of LED current. The PWM functions by shorting out the LED with a parallel switch allowing high PWM dimming frequencies. High frequency PWM dimming allows digital color temperature control, interference blanking, field sequential illumination, and brightness control. Additional features include thermal shutdown, VCC under-voltage lockout, and logic level shutdown mode. The LM3434 is available in a low profile 24-pin WQFN package.

LM3434主要特性:

Operating Input Voltage Range of –9V to -30V w.r.t.LED Anode
Control Inputs are Referenced to the LED Anode
Output Current Greater than 6A
Greater than 30kHz PWM Frequency Capable
Negative Output Voltage Capability Allows LED Anode to be Tied Directly to Chassis for Maximum Heat Sink Efficiency
No Output Capacitor Required
Up to 1MHz Switching Frequency
Low IQ, 1mA Typical
Soft Start
Adaptive Programmable ON Time Allows for Constant Ripple Current
24-Pin WQFN Package

LM3434应用:

Projection Systems
Solid State Lighting
Automotive Lighting

图1. LM3434框图

图2. LM3434典型应用电路

图3. LM3434输出10A的应用电路

图4. LM3434输出20A的应用电路