MLX10803 LED Driver IC
The MLX10803 circuit is one of the most flexible and useful LED drivers on the market. It can be used to make cost effective and robust solutions in current ranges from 20mA to 20A with operating voltages from 6V and up, even applications using thousands of volts.
This simple buck converter circuit (Fig. 1) can be used in LED lamp applications up to 25W. The maximum number of LEDs that can be connected is limited only by the operational voltage. The sum of the diode voltages of the LEDs must be lower than the input voltage. Every kind of active current regulation generates ripple on the regulated output, this ripple can generate electromagnetic radiation (EMR), resulting in electromagnetic coupling to the surrounding electronics (EMC).
Fig. 1. The schematic of the simplest HV application using MLX10803
The MLX10803 and the applications described are designed to minimize EMR. Additional care has to be taken when designing the circuit board and the physical application.
Compliance testing is recommended. To assist with picking the components in the regulation loop, Melexis offers a tool to help you calculate the values. This small Excel spreadsheet tool can solve most simple application solutions, more complex component selection can be resolved with the assistance of Melexis application engineers.
If your application is a lamp that must work with a wider voltage range there are more suitable solutions available from Melexis. Designs from the simplest HV application (as outlined in Fig.1), to advanced LED drivers with 99% Power Factor Correction, which schematic can be seen in HV Application Note for the MLX10803.
This advanced design is helping a Melexis customer offer innovative parking lot and municipal street lighting solutions. The efficiency achieved in the driver circuit can allow recovery of the costs to replace the existing sodium vapor or mercury vapor lamps in just a few years depending on local energy prices.
Melexis applications notes, datasheets and new products are continually being updated. In order to keep you current, our website allows registered members to subscribe and receive automatic update notices on any technical information. An online support forum staffed by applications engineers can also provide answers to any questions.
The solid state lighting market is at its infancy and yet the promise of greener, more efficient solutions to illumination has already driven rapid progress toward cost effective replacement of inefficient incandescent and mercury bearing fluorescent lighting.
Calculation for LED Drivers (link to document)
The excel coil and sense resistor calculation sheet.
Version 1.6, release date 18/8 2006
This is a tool to balance your LED-driver circuit, and to estimate component values. The tool describes a bit simplified how the wave from of the current over the diodes will look like for different number of diodes, type of coil and current sensing.
Play with this tool and you will get a sense how to design your specific circuit.
This tool does not give correct values in extreme cases when the supply voltage is close to the sum of LED diode voltages. All calculation has to be followed up with real test design and measurement.
The last pic: A streetlamp application in a BOOST BUCK configuration with 99% PFC. This specific application uses 4 MLX10803 per lamp.
Special Offers
. Certainly it would be easier than manually wiring up the array. 
Linear Mode
