Failsafe smart LED module with thermal management, string current balancing and commutation for lifetime extension

A new LED driver architecture is presented for increasing the lifetime and reliability of solid-state lighting modules. The architecture targets indoor/outdoor industrial applications, where the overhead cost of a smart LED driver is outweighed by the added value of improved lifetime and fault tolerance. The system includes two complete sets of white LEDs and associated current-mode drivers. The digitally controlled dc-dc converters communicate with each-other to smoothly transfer current from one set of LEDs to another at a regular commutation interval. A low-power pulse-frequency-modulation mode is used to conserve power in the LED set that is off. The redundancy is also exploited to perform precise current balancing and health monitoring of the individual LED strings, while the total light output remains constant at all times. The architecture is demonstrated on a 25 W module with 154 white LEDs, which forms 1/4 of a full luminaire.