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13 Threads found on Led Current Regulation
Does the led/resistor need a regulated voltage? Why not drive it from the input voltage? That will take a burden off your regulating device. A zener is the simplest method of voltage regulation. You must select the series resistor so it allows some current to go through the zener, and some current through your load. If you (...)
Unless you know that your supply is regulated , expect up to 40% variation from full load up to no led load. So choice of solution is best with LDO for efficiency and regulation NPN with zener is ok but not 1% as shown as they also have 7% tolerance typical at a max current and maybe 5% for a 1W type with less dissipation. A
The HV9861A is a Buck led current regulator which claims to be able to maintain a constant led current in spite of varying led load voltages, even though it only uses low side current sensing. Figure 1 , page 5 of the datasheet shows the great led current (...)
Dear All I have designed a boost converter led driver with TPS40211. Vin 6 - 8,5 V (2 cell Lipo) and output voltage 10 - 75 V and current is 0,08 A almost 6 W. You can see schematic attached. 105340 I have to change my design to 4 W constant power output. When the output voltage is increase, I want to decrease outpu
Hello, Does this 5W SEPIC led driver have a poor phase margin.? The led current oscillates at ~500Hz (loop crossover frequency) during start-up, as it rises upwards, -however, there is absolutely no led current overshoot, and the led current never oscillates when it gets (...)
Offline led drivers use primary side control (via the bias winding) in order to regulate the output led current when triac dimming is used. eg the linkswitch ph family.... Surely one cannot achieve tight regulation of output via the bias winding?, since after all, it is separated from the secondary (ou
There are usually reasons why you want a led current to be regulated. Regulating the input current of a switched mode led supply isn't the same thing and in most cases won't serve the purpose of led current regulation. It also might risk to exceed the rated (...)
the best white led's will include back to back zeners for ESR protection, since Vr=-5Vmax, this can also serve as forward drop protection in case of open circuit. The best modules will use constant current regulation with enough headroom to allow for Vf variation of 10% or more. THe information supplied so far is inconsistent. Please (...)
Basically, on the right side of the optocoupler (=led side) the system has essentially a voltage reference (such as TL431) monitoring the output voltage and controlling the led current accordingly, You could get the same effect by just using an ordinary transistor instead of optocoupler's output transistor, and regulating the base (...)
Hello I want to drive a 100V series strings of leds in a TV backlight. max current is 500mA. Is it ok to simply use an isolated converter to give the 100V rail, (obviously regulation would ultimately be done on led current) ....or does the secondary voltage need to be less than 60 VDC for safety (...)
Richtek Technology Corporation : Products : Product Portfolio led driver from Richtek. It is much cheaper.
In IC, there are many cases for switching between off and satuation region. One of example is led driver for very large screen. In satuation region, it works in current regulation and transistor work in satuation region for most of cases. PWM switching is used to control led dimming. As a result, led (...)
I think you may as well just use 1 current limiting resistor in each string, it would probably give equal performance as your current setup. The best way is what Kral suggested regulate each string. Either get a cheap quad opamp or some dual transistors for mirrors. TI also makes some inexpensive SMPS boost led drivers,so you could just (...)