Application Note # 5
Controlling Brightness Using Potentiometer on LS520 and LS460
The following applies to the Taiyo Yuden LS520 and LS460 dual tube inverters.The LS520 and LS460 inverter brightness control is done by applying a DC bias of 0 to 2.5V to the brightness control pins. Unlike the single tube inverters like the LS380s, brightness control for these dual tube inverters cannot be accomplished with a potentiometer. The reason for this is that the LS520 and LS460 have a voltage follower, or a sub-regulator built into the unit to synchronize both outputs. This voltage follower compensates for resistive load to the brightness control circuitry
However, by using a voltage separator circuit consisting of a potentiometer, a virtual brightness control by potentiometer can be achieved.
Note that current which will run between the brightness control pin will be in a trivial 3.0µA range.
