MDL or knowns as Mini Driving Light are very common now a days from generic all the way to expensive ones but they do have something in common. YELLOW beam as low beam and WHITE colored luminance as High beam or combination of two depending on the brand.
I have been puzzled about this kind of Auxilliary light for years pass but have no time dismantling one to have a look at the led constant current drivet and led chip used.
During my experiments on CREE LEDS and able to fabricate my own auxilliary light in the past before this MDL was introduced. I am fascinated by it
And so without further a do. I opened one generic Mini Driving light and able to read the schematic and find an appropriate data about it.
In the photo. There are so many manufactured that looks the same. But the quality of material are different especially the housing and heatsink used. The design varies too that affects the overall efficiency of the unit.
Differences of the inside!!!
This is the first item. In the photos they look the same on the outside.
But the inside isn't. Look at the design. Will this be efficient. I guess not.
With the led chip heating up during use, wo does the components of the led driver. This design is poor with THERMAL RUNAWAY on the parts that corresponds to the efficiency of the constant current driver.
And this is the second item. See the big difference. The led chip is isolated to the driver. Thus higher efficiciency than the first item.
The optic lens are the same. No major differences between the two.
THE SCHEMATIC!!!
Plain and simple, a boost converter led driver. Since the design used incorporated a series of led. The very common LED DRIVER used is
76cctC02A and according to the datasheet has the same part as
LN2576.
Overview of the IC.
■ Product Overview
76CCT is a non-isolated constant current LED driver chip with simple peripheral circuit and independent intellectual property rights VFPWM continuous working mode, suitable for 8-100V full voltage range.
76CCT uses PWM working mode, and a smaller inductor can be used in the application, which can effectively save the space of the whole machine. 76CCT realizes the two-function switching by controlling the MODE port. When MODE is suspended, it is the high-brightness mode, and when MODE is connected high, it is the low-brightness mode, in which the low-brightness current is 50% of the high-brightness current.
■ Application 76CCT
DC or AC input LED driver
RGB backlight LED driver
Electric bicycle lighting
Automotive lighting, etc
■ Product Features
Wide input voltage range: 8V~100V
Efficiency greater than 80%
Output current range: 100mA~3.5A
Power supply built-in 8V voltage regulator
Average current working mode
Built-in frequency jitter circuit
Built-in 100V power tube
With the versatility of the IC. it can be enhanced, neither can be used to dim the light half brightness with the MODE PIN enable.
Current setting
By setting different levels for MODE, the chip can achieve
Different functions.
When MODE is left floating or grounded, the chip enters high-brightness working mode;
When MODE is connected to VDD, the chip enters low-brightness working mode.
The current in low-brightness working mode is 50% of that in high-brightness mode.
There still room for improvement. Higher luminance can be achieved by using higher power leds to drive by this IC. And I am up for the challenge.
Soon i will post the project.
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