 Posted: Mon 3:03, 09 May 2011 Post subject: LED enterprise to the overseas market can have the |
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| the control unit can maintain a constant output current characteristics. led voltage characteristics from the work point of view, menu board such control device is most appropriate, it does not require additional current limiting impedance, the output can be connected directly in the led load. led control output current control devices, if not a stable output current, the internal characteristics of a constant current circuit is not perfect, such as internal limiting use of inductance or capacitance of the circuit. such circuits from the output side to watch the outputimpedance, less than a constant current output control device,but significantly higher than the control output voltage control devices.
thus, in testing, according to iec 61000-3-2 standards, measuring instruments and electronic control devices should be required between the bandwidth increases with a 5khz low-pass filter or filtering function used with this digital power meter (such as led billboard yokogawa wt2010 and wt3000, etc.), so as to ensure reasonable power factor of the project and accuracy of detection. (for the terms of the detection principle and the detailed requirements. it also provides bias current source and changes with the digital signal modulation current. design led drive led drive circuit must first consider the current peak, the peak drive current if more than the light signal will be produced overshoot phenomenon. and the resulting electrical signal at the receiver caused by the lower punch, led signboard coupled with the impact of noise from the amplifier, the result may be beyond the detection threshold comparator, resulting in errors. |
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