| 摘要 |
<p>PURPOSE: A switch mode power supply(SMPS), a constant current type SMPS controlling circuit of the same, and a light emitting diode(LED) signal lamp system using the same are provided to prevent the malfunction of a LED signal lamp by extending the life of LEDs. CONSTITUTION: An SMPS includes a pulse-width modulation(PWM) type power converter(100) and a constant current type SMPS controlling circuit(200). The PWM type power converter generates direct current output voltages based on alternating current input voltages. The PWM type power converter is composed of an electric wave bridge rectifier(110), capacitors(C10, C20, C30, C40), a transformer(120), a diode(D50), an inductor(L20), a PWM controlling signal generating circuit(130), and a switch element(M10). The constant current type SMPS controlling circuit includes a comparing circuit(210) and a reference voltage generating circuit(220).</p> |
