LED LINEAR CONSTANT CURRENT CONTROL CIRCUIT AND LED LIGHT EMITTING DEVICE

摘要

An LED linear constant current control circuit (300) and an LED light emitting device. The control circuit (300) is connected to an LED light string (200), which is formed by N LED light groups (LED₁, LED₂, …, LED_n-1 and LED_n) in series connection. The control circuit (300) comprises: a reference voltage generating module (300), for sampling an input voltage of the LED light string (200), and converting the input voltage to N reference voltages (V₁, V₂, …, V_n-1 and V_n) having different constant peak values but the same phase as the input voltage; and N output current control modules (CTR₁, CTR₂, …, CTR_n-1 and CTR_n), having control ends thereof that respectively receive the corresponding reference voltages, input ends thereof being respectively connected to output ends of the corresponding LED light groups, and output ends thereof being connected together in parallel and grounded through a first resistor (Re). When the input voltage of the LED light string (200) reaches a forward conduction voltage of M LED light groups, the first M LED light groups conduct, and a current corresponding to the M^th reference voltage is generated at the first resistor (Re) by the M^th output current control module. The present invention provides a high power factor and low total harmonic distortion, and is capable of preventing the current passing through LED lights from changing with a change in the peak value of the input voltage.