The SM8131B is a charge pump DC/DC converter that switches between x1 and x1.5 automatically. The SM8131B switches between x1 and x1.5 according to detected LED drive current, so that the battery life can be prolonged to the fullest extent. Since the connected LED are all detected for the switching, the SM8131B can respond to the variation of LED forward voltage. 6-channel of LED drive current control circuit is built-in, the SM8131B can control 1 to 6 lights of white LED, which are connected in parallel. The LED drive current per channel is set up by external resistor. Besides, by setting up SEL1/SEL2 pins, 6-channel of LED drive current control circuit can be divided to 2-groups, and input signal controlling of EN1/EN2 pins allow ON/OFF and dimming per group.