Vf is the forward voltage of the meaning, but not necessarily larger forward voltage, forward current is greater. You see as long as the recognition of a small book on the power led torch
Surface will have a Vf value, If there is a value, regardless of how much value is vf, (red, yellow, green, orange usually 1.8v-2.4v, white, blue, emerald Green is generally 3.0v-3.6v). Where Vf and If there is no proportional; but one yellow and one white light ratio, such as the yellow LED tactical flashlight. The voltage is 2.0v, white lamp voltage is 3.3v, 2.0v voltages in yellow and white lights in the Fengyun 3.3v voltage electricity flowing through them. Flow is the same, are 20mA, Vf and If here is not proportional. If is 20mA. The two are complementary. Such as the two white, one is 3.0v, 20mA, one is 3.4v, 20mA, meaning that the first one lamp, you give it 3.0v voltage, the current flowing through it hunting LED flashlight is a normal rated current 20mA, but the second teeth lights, you give it 3.4v voltage, current is flowing through it 20mA. Therefore, only specifically refers to the case of lamps with a Vf and If is absolutely proportional. Whether you use when Vf is much, as long as control flow through the lamp current of 20mA for all the LED bicycle is OK.