The main parameters of the LED desk light source are VF, IF, and others related to color / color temperature / wavelength / brightness / luminous angle / efficiency / power consumption, etc.. LED lamp is a PN junction diode forward voltage is applied, only to conduction current enough, VF forward voltage is LED light to establish a normal working state, the IF forward current is to promote LED light, brightness and current flow is proportional to the. White LED VF nominal voltage: 3.4V + 0.2V. LED light in mass production, each batch of LED VF has discreteness, for consistency requires customers to use the LED, the factory must according to different VF files for sale; otherwise it will lead to the LED lamp brightness the same batch production are different; LED IF working current is selected according to the application needs. Do not mix different current grades.