MR-16 LED驱动器和用于脉冲LED冷却器供电的5V辅助电源
Abstract: This applicaTIon note presents a reference design for a 4S1P MR-16 LED driver that provides 750mA to a string of four white LEDs (WLEDs). The circuit operates from a 24V source and is based around the MAX16820 hystereTIc LED driver. Also included is a MAX5033 24V-to-5V, 150mA switching power supply to power a NuvenTIx® pulsaTIng LED cooler.
The following are the electrical input requirements and output capabilities.
VIN: 24VDC ±5%
Temperature: +80°C (max) ambient
VLED configuration: 4 LEDs in series (16VDC, max), 750mA
Auxiliary output power: 5V at 150mA (average), 300mA (peak)
The reference design is discussed in detail below, with analysis of the main circuit blocks and layout considerations.
![MR-16 LED驱动器和用于脉冲LED冷却器供电的5V辅助,第2张 MR-16 LED驱动器和用于脉冲LED冷却器供电的5V辅助,Figure 1. Schematic of the driver design.,第2张](/upload/website_attach/20220726/200995232056268.gif)
Figure 1. Schematic of the driver design.
![MR-16 LED驱动器和用于脉冲LED冷却器供电的5V辅助,第3张 MR-16 LED驱动器和用于脉冲LED冷却器供电的5V辅助,Figure 2. Photo of the PCB. The board was designed to fit directly into an MR-16 assembly.,第3张](/upload/website_attach/20220726/200995232056954.jpg)
Figure 2. Photo of the PCB. The board was designed to fit directly into an MR-16 assembly.
![MR-16 LED驱动器和用于脉冲LED冷却器供电的5V辅助,第4张 MR-16 LED驱动器和用于脉冲LED冷却器供电的5V辅助,Figure 3. Revised layout of the PCB (updated from the board in Figure 2).,第4张](/upload/website_attach/20220726/200995232057481.gif)
Figure 3. Revised layout of the PCB (updated from the board in Figure 2).
Design AnalysisDesigned to fit directly into an MR-16 assembly, this reference design delivers 750mA to a string of 4 LEDs from a 24V power source. The MAX16820 provides hysteretic control and regulates the current through the inductor and the LEDs. Meanwhile, the MAX5033 provides power to a pulsating cooler through the J2 connector. The cooler presents a sinusoidal load of 300mA peak and 150mA average to the power supply.
The R3 resistor is in the circuit to satisfy the stability requirements (with a ceramic output capacitor) of the MAX5033.
A provision was made for PWMing, but not tested. The center pin of J1 was routed directly to the DIM input of the MAX16820.
Power-Up Procedure
- Connect 4 LEDs in series to the LED+ (anode) and LED- (cathode) pins.
- Attach a 300mA load to J2.
- Attach a 24V, 1A power supply to J1.
- Turn on the power supply.
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