Constant Current Paralleling Controller for Mid-Power LED

A simple, cost-effective current sharing controller integrated in a LED module is presented. By this technology it is possible to drive high luminous flux, SELV-compliant LED arrays, using a large number of mid-power LEDs arranged in a series-parallel configuration. Still a conventional constant current power supply can be used. This novel current sharing concept uses one dissipative, cost-effective, balancing current sink per string, implemented by using a single operational amplifier, and one global averaging circuit. The document describes the circuit and corresponding design equations. Operation is demonstrated by measurements.