The load characteristics of LED determine that only power suppliers with higher reliability can be used. Within a certain section, increasing the external voltage will cause an exponentially increased current. When LED Lights work in the normal condition, subtle changes in voltage will cause widely vibrations in current. Thus most switching power suppliers are no longer suitable for LED applications. Because the output of switching power suppliers is not a constant value. However, how to choose right LED power suppliers for LED applications?
LED is very sensitive for input voltage. The normal working voltage for LEDs is around 3.0V-3.6V (different power has different input voltage). A slightly fluctuation in input voltage will lead to a violent change in current, consequently causing a violent power output. If the vibration exceeds a certain threshold, accidents may happen. Experiments proved that adding voltage suppressing components (TVR, TVS) in circuits is useless.
Reliability and efficiency are constrained by each other. Power suppliers with higher efficiency must have a lower reliability, vice versa. In order to reduce the influence of output voltage to input voltage, electrical energy must go though several transformations. For example, the reliability of BUCK circuit is not very high. But BUCK-BOOST circuit has much better reliability than BUCK circuit. This has been proved. Known by those who had electricity background, when the switch of BUCK circuit is turned on, LED HIGH BAY loads and inductances are cascaded in the circuit under 300V external voltage. BUCK-BOOST circuit separately charge inductances firstly. When the BUCK-BOOST circuit is switched off, then inductances in BUCK circuit will transmit electrical energy to LEDs. The difference between them is BUCK circuit will work directly under 300V voltage in a period of time while LEDs in BUCK-BOOST circuit will not be explored under such high voltage. Thus the later has a much better reliability than the former. And relatively, BUCK-BOOST circuit actually has two electrical transmission sections: from power supplier to inductances and then from inductances to LEDs while BUCK circuit need only one step to charge LED STREET LIGHTS. In the aspect of efficiency, BUCK circuit has a better performance.
Thus currently used LED power suppliers are followed such law: isolated circuit has a better reliability than non-isolated circuit. Low voltage circuit has a better reliability than high voltage circuit.
