How to Calculate What Size Led Power Supply and Controler Is Needed for Led Rgb 5050 Light
Definitions and Formulas Used for Adding
Unmarried LED
A light-emitting diode (LED) is a semiconductor light source with two or more leads. Monochrome LEDs usually have two leads, bi-color may have two or 3 leads and tri-color and RGB LEDs commonly have four leads. An LED emits light when a suitable voltage is practical beyond its leads.
Conventional infrared LED and its electronic symbol. The foursquare semiconductor die is installed on the negative (cathode) lead. The thin wire connects the square semiconductor die to the positive (anode) lead.
To power a single LED, a uncomplicated LED excursion with a serial current limiting resistor is used. The resistor is necessary because the voltage drib across an LED is approximately constant over a wide range of operating currents.
| LED Colors, Materials, Wavelength and Voltage Drop | |||
|---|---|---|---|
| Colour | Semiconductor Cloth | Wavelength | Voltage Drop |
| Infra-Cerise | Gallium arsenide (GaAs) | 850–940 nm | <i.vi V |
| Red | Gallium arsenide phosphide (GaAsP) | 620–700 nm | ane.six to two.0 V |
| Amber | Gallium arsenide phosphide (GaAsP) | 590–610 nm | 2.0 to two.one Five |
| Yellowish | Gallium arsenide phosphide (GaAsP) | 580–590 nm | two.1 to 2.2 V |
| Green | Aluminium gallium phosphide (AlGaP) | 500–570 nm | one.9 to 3.v V |
| Blue | Indium gallium nitride (InGaN) | 440–505nm | 2.48 to 3.6 V |
| White | RGB LEDs or phosphor material | Wide spectrum | 2.8 to 4.0 Five |
LEDs and resistors deport very differently in circuits. The resistor's behavior is linear, according to Ohm'south constabulary
Current-voltage characteristics of typical LED of different colors
If the voltage beyond the resistor is increasing, the electric current is besides proportionally increasing (we assume that the resistor value stays the same). On the other hand, LEDs carry differently. They comport as ordinary diodes according to their electric current-voltage feature bend shown in the picture for LEDs of different colors. The curves show that the current through the LED is not directly proportional to the voltage across it. The electric current through the LED is dependent exponentially on the forward voltage. That means that merely a small modify in voltage will cause a large change in current.
When the LED frontward voltage is small, its resistance is very high. If the voltage reaches the characteristic forward voltage value shown in the specifications, the LED "turns on" and its resistance quickly drops off. If the practical voltage is slightly larger than the LED's forward voltage, the forward voltage exceeds the recommended value, which can exist ane.5 to four volts for LEDs of different colors. In this example, the current quickly increases and the diode can be damaged. To limit this current, a resistor is placed in series with the LED to go along the current at a specific level shown in the LED specifications.
Calculations
A rectangular LED with a apartment top used in applications like a bar-graph brandish
The value of the series current limiting resistor R s can exist calculated using Ohm's law formula in which the supply voltage 5 s is offset past the forward voltage drib across the diode 5 f:
where Five s is the ability supply voltage (for example 5 Five USB power) in volts, Five f is the LED forrard voltage drop in volts and I is the LED electric current in amperes. Both 5 f and I f can exist plant in the LED manufacturer specifications. Typical values of V f are shown in the tabular array to a higher place. Typical electric current of LEDs used for indication is 20 mA.
After the resistor value is calculated, a nearest higher standard value is selected from the preferred resistor numbers. For example, if our calculation shows that we need a resistor R s = 145 ohm, we will take a resistor R sp = 150 ohm.
The current-limiting resistor dissipates some ability, which is calculated as
Orange LEDs usually used in routers to bear witness 10/100 Mbps speed; green LEDs show thousand Mbps speed
Unremarkably, the resistor wattage is selected close to twice the value calculated here. For case, if the value of the power is 0.06 W, we will select a resistor with a wattage rating of 0.125 or 1/8 Due west.
At present we will calculate the efficiency, which will prove how much of the total power consumed by the excursion is used by the LED. The power prodigal past the LED:
Full power consumption
LED circuit efficiency
To select the power supply, we volition calculate the current drawn from the ability supply:
A LED strip with 5050 diodes; the numbers l and 50 betoken the length and width of the chip in millimeters; the series 150-ohm resistors are pre-installed on the strip
LED Arrays
A single LED tin can be driven using a current-limiting resistor. LED arrays that are increasingly used for area illumination, calculator monitor and TV display backlighting, and other purposes crave specialized power supplies. We are all used to voltage-stabilized power supplies. However, ability supplies for LED driving must stabilize their current, not voltage. In whatsoever case, current-limiting resistors are always used in LED arrays.
If more than ane LED is necessary for the application, strings of multiple LEDs connected in series can exist used. For a cord of LEDs connected in serial, the source voltage must exist greater than or equal to the sum of voltages across private LEDs. If information technology is greater, then a single current-limiting resistor per string can be used. The current through each diode is identical, which ensures uniform effulgence. It is by and large best if all LEDs connected in series are all of the same type.
Withal, in the case of a unmarried LED open-mode failure, which is the most common failure mode, the entire LED cord goes dark. In some designs, a special shunt protection device is used to prevent this. Zener diodes connected in parallel with each LED can exist used for this purpose. This approach is expert for depression-ability LEDs, but for loftier-power LEDs used, for case, in street lighting, this arroyo is not cost-effective, and more complex shunt protectors must be used. Of course, this adds to cost and infinite requirements. At present (2018), information technology can be observed that LED street lights, with a planned service life of x years, serve no more than a yr. The same applies to household LED lamps, including lamps made past well-known manufacturers.
This LED strip is used for illumination of the LCD television console; two such strips are installed on both sides of the screen panel. This design allows the thinnest displays. Note that televisions with LED-backlit LCD panels are normally marketed as LED TVs. The real LED TVs use OLED displays.
When calculating the required resistance of the current limiting resistor R s, all voltage drops across each LED needs to exist considered. For example, if a voltage drop across each illuminated LED is 2 V and we continued v LEDs in series, then the total voltage drop beyond all five will be 5 × two = 10 V.
Several identical LEDs can be besides connected in parallel. Parallel LEDs must have matched forward voltages Five f, otherwise, they will not take a like current through them and therefore their brightness volition be different. For a parallel connectedness of LEDs, it is a good idea to connect a current-limiting resistor in series with each diode. In the parallel connection, an open up-circuit failure of any single diode volition not lead to the entire diode ready going dark — it will be operated commonly. Another problem of the all-parallel connection is the choice of an efficient depression-voltage and high-current power supply, which, at the same power rating, tin can be more than expensive than conventional power supplies for higher voltages and lower currents.
In this common LED street lighting fixture 8 strings of five powerful LEDs for a total of xl LEDs are driven by an efficient constant electric current power supply; note that two strings (top left and bottom right) are dark in this fixture installed but a couple of months agone considering in each of them i diode failed and protection devices are non used or not working
Calculations of the Current-Limiting Resistors
If the number of LEDs in a serial cord Due northLEDs in string (denoted as Ns in the entry field) is non entered, then it volition exist determined hither. The maximum number of LEDs in a series cord Due northLEDs in string max for a given power supply voltage 5 south and LED's forward voltage Five f:
If the number of LEDs in a series string NorthwardLEDs in string (denoted as Norths in the entry field) is entered then the maximum number of LEDs in a series string NLEDs in string max is adamant every bit
A 3014 (iii.0 × 1.4 mm) SMD LED used in LCD Television with LED backlight
The number of strings with the maximum number of LEDs in the string Due northstrings:
The number of LEDs in the remainder shorter cord Nbalance LEDs :
If Nremainder LEDs = 0 then there will be no additional string.
The resistance of the current limiting resistor for strings with the max. number of LEDs:
The resistance of the current limiting resistor for strings with fewer LEDs than the max. number of LEDs:
The mutual power P LED dissipating past all low-cal emitting diodes:
The power dissipating by the resistors:
Flexible LED displays in a public place; a LED display uses an assortment of light-emitting diodes as pixels; because of LED very high brightness, they are unremarkably used outdoors as billboards or highway destination sights that are visible in bright sunlight. LED displays can also provide general illumination and are often used as photo and video lighting with variable color temperature
The ability rating is adamant with a condom factor g = ii, which ensures the reliable operation of the resistor. Select the resistor power rating, which is twice higher than the calculated power from the post-obit values: 0.125; 0.25; 0.five; ane, 2, iii, four, 5, 8, x, xvi, 25, 50 Due west.
Calculating the common ability P R dissipating by all resistors:
Computing the common power P total dissipating past the array:
Calculating the current that the array draws from the ability supply:
Calculating the array efficiency:
You may also be interested in the Luminance, Luminous Intensity and Illuminance converters.
Source: https://www.translatorscafe.com/unit-converter/en-us/calculator/led-resistor/
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