LED connection mode (series/parallel) and wide voltage range: in order to enable LED fluorescent tubes work under wide voltage range: 85VAC-265VAC, the connection mode (series/parallel) of LED tubes is fairly important. Current power supplies generally use non-isolated step-down power supply. In wide voltage requirements, the maximum output voltage should be no more than 72VAC, the input voltage range is 85VAC-265VAC. In other words, the series string number should be less than 23. Also need to limit the number of parallel strings. Too much current will generate more heat. Normally, 6/8/12 branches with the total current less than 240mA.
Relations between LED Tunnel Light series-parallel connection and PFC power factor, wide voltage range: there are three major cases of PFC power supplies in the market: a. without PFC special circuit, the PFC is normally about 0.65; b. with passive PFC circuit, the PFC is normally around 0.92; c. with active source 7527/6561 circuit, PFC can reach up to 0.99. But this case is twice as expensive as the second one. Comprehensively, b is the most commonly used mode.
Precision of constant current: some constant current sources in the market have a relatively low precision, like the popular PT4107/HV9910/BP2808/SMD802 constant current plans with an error of +/- 8% or +/- 10%. In normal condition, +/- 3% is enough. In this way, 6 branches with error +/- 0.5% for each branch, or 12 branches with error +/- 0.25 for each branch can meet such requirements. High precision will also increase the production cost of LED fluorescent tubes. But for LED lamps, 17mA or 17.5mA does not make too many differences.
Isolated/non-isolated: generally, isolated power supplies can make as 15W. LED drivers are too large to be embedded into LED tubes with limited size. Thus isolated power supplies can only be made as 15W tops, hardly find power supplies in the market with output power greater than 15W. In terms of LED tubes, isolated drivers have very low cost-effective. Non-isolated driver is the mainstream.
Power efficiency: the ratio of output power to input power. This parameter is very important. Low power efficiency means that most of the input power is converted into thermal energy and wasted. Such drivers will generate a large amount of heat within tubes. LED is a type of component that vulnerable to heat. Thus LED lighting fixtures need high power efficiency, normally no less than 80%.