Working voltage and current during this test before making deal with samples tested at the standard 5.2 and / or 5.3 classification, only for the correct classification, to the condemnation and to complete the standard 6.1.2 This chapter corresponds to the test correctly. The design for the LED Display device, it must first request by this chapter, the output characteristics of the position. Can be classified as follows:
(1) control the output voltage of the LED control device If you have a stable output voltage, the product should be marked “rated output voltage”, and should accordingly be marked “maximum output current” or “maximum power output.” LED control device should belong to such AC / DC conversion (including switching AC / DC conversion) of the power supply. It features in a certain range of load current, output voltage is almost no change.And when the supply voltage range of ± 10% variation, the output voltage is almost constant. That the output from the control device to see inside, with a very low output resistance. Because the LED has a prominent “negative resistance temperature characteristics”, that is, when the LED work, as the PN junction junction temperature increases, the PN junction forward voltage will be increased linearly, so the output voltage stable LED control devices applies only to their own devices with a limited flow of LED modules (at least one current limiting resistor), or for larger power LED Lighting is not work.
[Table] Figure 3 control the output voltage of the LED controller test circuit
LED control device if you do not have a stable output voltage, that is, when the load changes in the nominal range or power supply voltage rating of ± 10% in the range of changes, the output voltage in a range of significant change. Such LED downlight watch from the output control device in, output impedance has a constant voltage output than the type of LED control to high, but significantly lower than control LED current output-type controls. Such circuits can be connected LED work-limiting impedance of the smaller LED can work. Such controls should also be marked LED rated output voltage and maximum output current.
LED control output voltage control devices the most obvious feature is its rated voltage, the output circuit at light load (for example, 20% to 30% load rate) and full load conditions, little change in the output voltage (output voltage change rate is generally not more than 30%), but if the rated output of each single string of one more loop LED will not work.
Test line in Figure 3, for a stable output voltage control device, when the input voltage rating of 92% to 106% range changes, the output voltage change compared to the rated voltage of LED modules, the deviation should be less than & # 177; 10%, for a non-stable output voltage control device, at rated input voltage, output voltage should be in line with the LED spotlight are rated voltage ± 10% range.
(2) control the output current control device <br /> LED control LED output current control device, if a stable output current, with a constant current source circuit that is internal, should be marked on the product “rated output current” and “maximum output voltage. “ LED with constant current characteristic control device of the biggest feature is to watch from the input side, with a high output impedance, connected in its output a series of LED, as long as the series of LED forward voltage accumulated value does not exceed the maximum output voltage, in this context, several LED strings or less more than a few LED strings, the control unit can maintain a constant output current characteristics. LED voltage characteristics from the work point of view, such control device is most appropriate, it does not require additional current limiting impedance, the output can be connected directly in the LED bulb.
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 output impedance, less than a constant current output control device, but significantly higher than the control output voltage control devices. Obvious feature of these controls is that as long as the output of the LED forward voltage loads in series additive control voltage is not higher than the maximum output voltage value, more or less strings string a few of several LED strip, the control device fundamental change in the output current does not exceed 30%, and also guarantee direct limit with no additional impedance LED work.
LED control output current control devices of the most distinctive features is that when the supply current in the range of ± 10% change, the control device does not require additional current limiting impedance loads directly to ensure that the appropriate LED to work.
Test circuit shown in Figure 4, a stable output current for LED control device when the input voltage at 92% to 106% range changes, the output current and is equipped with a LED rated current than the deviation is less than ± ; 10%. Does not have a stable output for LED current control device, when the input voltage rating, the output current and is equipped with the LED panel‘s operating current than the bias should be less than 10%.
Figure 4 controls the output current of the LED controller test circuit