The invention provides a constant-current
driving circuit for an LED switch. The constant-current
driving circuit for the LED switch at least comprises a
voltage input module, an LED module, a power tube, a filter, an
error amplifier, a
pulse width modulation circuit, a
current limiting circuit, a
control circuit and a
driving circuit, wherein the LED module is connected with the
voltage input module; the power tube is connected with the LED module;
constant current can be achieved by adjusting the
duty cycle of the power tube; the filter is connected with the output end of the power tube and is used for filtering sampling
voltage; the
error amplifier is used for comparing the sampling voltage with reference voltage; the
pulse width modulation circuit is used for generating a PWM
signal; the
current limiting circuit is used for adjusting the amplitude of the PWM
signal; the
control circuit and the driving circuit are used for adjusting and driving the
gate voltage of the power tube. According to the constant-current circuit for the LED switch, the
constant current of the LED can be achieved by adopting a switching topology and
linear topology combined novel topology structure, no
inductor or
electrolytic capacitor is needed, the power tube is controlled in a switch mode, and the efficiency is higher than that of a pure
linear control structure.