kswmwe84
02-01-2012, 11:41 AM
pwm conol of power mos operates in average oscillation frequency of 67khz in order to ensure a constant output current and built-in led output of a standard reference vol***e (0.3v), thus realizing the feedback conol. when the operating vol***e vcc vol***e is lower than it would stop working. xi alpha semiconductor companies just set up early this year though, it has proven to be song, at the recent iic-china autumn exhibition in xi'an station, alpha 20w and 120w exhibited no elecolytic capacitors in the led lighting power supply, efficiency, respectively astonishing 90% and 95%, respectively, for indoor lighting and seet lighting market. both products are developed with their own led drivers, mosfet and schottky diode, which 120w led lighting driver circuit power supply comes with a complete, open circuit protection, and through the emc certification testing. marker boards (http://www.flashingledboard.com/)the measuring device because the silicone oil is almost the same rate of temperature rise, and the implementation of stepwise heating and temperature conol, which can guarantee a reasonable rate of temperature rise under the conditions of accurate results, and the detection time (from 25 to 140 approximately 2.5 hours or so) can significantly below the current detection device already on the international measurement of time. already on the international test device is a single silicone cylinder sucture, the measuring device with double silicone oil cylinder sucture, when completed, after a sample measurement, the replacement of a silicone cylinder, immediately began the second set of led testing. the measuring device measuring the temperature at each point of the measured temperature and the led forward vol***e drop, the import to a data**** compiled by the software generation vf-tj curve.led signs outdoor (http://www.flashingledboard.com/)the measurement methods described in the junction at home and abroad on the led junction temperature, can only touch a single led or a single block of led junction temperature and thermal resistance measurement, there is no complete led lighting apparatus within the junction temperature and thermal resistance of the actual work measurement method, the following describes a complete led lighting apparatus within the actual work measurement junction temperature and thermal resistance. 1) vf-tj curve (1) maix led lighting in the middle of a series led group at or near the middle of an led as the test led, the circuit connection according to figure 2, in which an led's heat sink (led itself brought a small radiator) on the glue of a thermocouple.led signage (http://www.flashingledboard.com/)