A balance circuit includes a reference circuit
configured to generate current through strings of light emitting
diodes (LEDs). The reference circuit includes a first string of LEDs
in series coupled to a collector node of a first transistor. A base
drive current resistor is connected between the collector node and a
base node of the first transistor. A base emitter resistor is
connected between the base node and an emitter of the first
transistor such that a reference voltage is generated on the base
node during operation. Another stage receives the reference voltage
to generate a tracking current through a second transistor and a
second string of LEDs connected to a base of the second transistor,
wherein a current through the first string of LEDs is uniformly
tracked by the tracking current through the second string of LEDs.
