The LM3466 integrates a linear LED driver for lighting systems which consist of multiple LED strings powered by a constant current power supply. It balances the current provided by the supply in a pre-set ratio for each active LED string, where an active string is a fully turned on LED string, regardless of the number of strings connected to the supply or the forward voltage of each LED string. If any LED string opens during operation, the LM3466 automatically balances the supply current through all of the remaining active LED strings. As a result, the overall brightness of the lighting system is maintained even if some LED strings open during operation.

The LM3466 lighting system is simple to design owing to a proprietary control scheme. To minimize the component count, the LM3466 integrates a 70-V, 1.5-A, N-channel power MOSFET with a current limit of 2.06 A. To add one more LED string to the system, only a single resistor, a capacitor, and a LM3466 are required. Other supervisory features of the LM3466 include under-voltage lock-out, fault reporting, thermal latch off, and thermal shutdown protection.

The LM3466 consists of only linear circuitry so that the EMI of the application circuit is not deteriorated. The LM3466 lighting system is EMI friendly if the constant current power supply used is complied to EMI standards. The LM3466 is available in the DDA-8 exposed thermal pad and TO220-7

• Easy to Design for Lighting Systems Consisting of Multiple LED Strings (Supports Modular Design)
• Automatically Balances the Current of Every Active LED String, even the Forward Voltage of Each String is Different
• Easy to Pre-Set and Fine-Tune Current Ratio Among LED Strings (e.g., color temperature adjustment or CRI Enhancement)
• ±1% Current Accuracy at Room Temperature and ±1.5% Over Temperature
• Maintains Constant Output Power if Some Strings Open (inactive) by Automatically Balancing the Current of Remaining Active LED Strings
• Works with a Constant Current Power Supply (ac/dc or dc/dc), and no Communication to/from the Constant Current Power Supply is Required
• Operates with Minimum Voltage Overhead to Maximize Power Efficiency
• Wide Input Voltage Range from 6 V to 70 V
• Fault Status Output
• Thermal Shutdown
• Integrated 70-V, 1.5-A MOSFET with 2.06 A Current Limit
• Maximum 70-V per LED String, 20 LEDs
• Linear Circuitry Does Not Deteriorate EMI
• DDA-8 Exposed Thermal Pad and TO220-7 Packages