An LED driver circuit is provided for driving a multi-channel LED string with constant and balanced current. The driver circuit includes a half-bridge inverter and a resonant tank circuit in a power stage. An isolating (first) transformer includes a primary winding coupled between a resonant tank output and circuit ground and a plurality of secondary windings, while a balancing (second) transformer includes a plurality of balancing windings. A plurality of output stages each provide an output power to a respective load, and each of the output stages further includes one of the balancing windings of the balancing transformer and one of the secondary windings of the isolating transformer coupled in series, and a rectifier circuit coupled to an output end of the series coupled windings. In an embodiment, an impedance value of the balancing transformer is further configured to be greater than three times a maximum load impedance value.