Constant current drivers on LED strips
Constant current drivers are significantly improoving the quality and stability of our LED strips.
Due to a fact, ,that LEDs are slowly changing their parameteres, such as brightness, Voltage , resistance, etc, it is absolutely neccessary to drive LEDs with constant current. Only this concept can guard the LEDs and prevent from damages due to overcurrent which happens during lifetime when LEDs change their internal properties.
There are basically 2 systems of constant current systems :
A. constant current driver is centralized - multiple LEDs are in series, and the series of LED strings are connected in parallel. As you can see, the schematic is very simple, there are no components to actively protect the LEDs. It is also very cheap for production.
B. Constant Current drivers are decentralized (LED strips with constant current drivers) - each serie of LEDs (1segment) contains 1 independent current driver (a device ensuring each LED in its LED series will have exact current/brightness. LED line made of 100segments will contain 100 tiny current drivers (1pc for each segment)
As you can see, there is extra component named CC IC (Constant current IC) attached independently for each LED string of series.
Someone might get confused with these options, let's explain it little bit in depth (for better understanding pros and cons)
A. Constant current driver is centralized
In such scenario, normally there is one Constant Current power supply Unit (say driver with 500mA output) powering say 10pcs constant current LED modules. We refer to it as "modules", as they are without any "protective device on the board"...the constant current device is only in the "Power supply". This concept can reach superior efficacy (as there is no other component than LEDs), resulting in transfroming 100% of output energy into LED energy, which emits the light.
This is nice scenario, unless :
installation contains say 100 or 500m of linear light (resulting in 100pcs of constant current power supply scattered along the LED line, which is expensive and time consuming )
one or more LED from series / modules will disconnect or diye (due to connector issues, or installation problems such as ESD, etc.)..then the rest of LED modules will be forced to consume current which was meant for this dead LED module, resulting "overpowering" and faster decay of the rest of the installation
you need to scale in/out the installation - every scale out requires special wiring to interconnect the modules in series/parallel connection, which must be compatible with used power supply. The change can not be done while running the installation, it is neccesary to power off the supply, do the changes and only then power up it again.
disconnecting or re-connecting the wires during work (secondary side) leads to permannent damage of LED modules, mostly not visible immediately, but only after several months.
So we reinvented the LED strips and created MASTER portfolio.
B. LED strips with constant current drivers
We have included best of all worlds :
constant current drivers are de-centralized - which means each LED string (=segment) contains 1 independent constant current driver. All segments are then connected in parallel. Each segment is protected for overcurrent independently. Failure of 1 single LED will lead to failure of single segment only, not causing failure of other segments.
24VDC constant Voltage power system has many advantages (wide range of power supply 1W-6000W ) allowing for easy scaling of the installation from 1segment to almost any size with no effort and with only few components (1 power supply, few cables and hundreds of meters of LED strips....easy as pie)
And the best is : when using the constant Voltage system (24VDC) the installation is highly scalable : adding or removing LED strips from installation can be done anytime, with no special wiring, and even while in operation.
NO! 12VDC NO! Please NO!...unless you have restrictions to use very low voltage system (due to safety regulations : such as wet saunas/wellness, etc.) In all other situations using 24VDC allows us to used 1 extra LED , which will turn the otherwise consumed energy to light (12V LED strips can contain only 3LEDs due to LED voltage 3x3.1V=9,3V which is just bellow 12VDC, there is not Voltage range to add 4-th LED), oposite that 24VDC strips can contain upto 7LEDs in series (7x 3,1V =21,7V which is just bellow the 24VDC power system) Having 7LEDs per segment instead of 3 LEDs per segment, lead to 16% better efficacy when installed similar type LED strips in same length!
Easy dimming with PWM modulation - PWM becomes one of the best dimming systems due to superior efficacy and very low heat development. This type of dimming method is used widely in almost everywhere : from low end devices found on internet, to sophisticated high-end controllers of all brands ( OSRAM, Philips, etc.)...so choosing the best controller for the installation is piece of cake too : KNX, DMX, DALI, Switch-Dimm, RF Dimm, Wifi, BT, 0-10V, 1-10V, etc etc...
Offcourse someone might say this kind of LED strips have their disadvantages. After a very close evaluating cons and pros and findning out what is physically happening behind the "words", almost anybody will find that these so-called disadvantages are basically "very great advantages", or sometimes the so-called dis-advantages are mis-understood correctly, few of them here :
- LED strips with constant current drivers are not easy to work with
be carefull : LED strips with constant current drivers are NOT the same as Constant current driven LED Modules (described above...normally there is never information about 12V or 24VDC system)
- it is not possible to dimm it with analugue dimming systems
YES, that is true! Thankfully! ...analogue dimming means "that the LED strip will have different brightness at different Voltages (here comes in play the Voltage drops always experienced on el. wires and the LED strips itself-allowing to dimm the LED strips with analogue dimming will cause the beggining of the LED strip to be 100% bright, yet its far end will have much lower brightness...causing great problems in lifetime, colour consistency, and almost impossible to install multicolour (RGBW) LED strips in longer distances on longer cables (different shades of colour on beggining and far end)
Someone might think that any Constant Voltage LED strip will possess the above advantages.
Read carefully or you could be very wrong!
Constant Voltage system is good thing, but the important thing here is the "decentralized" current regulator, which is often replaced with passive components (resistors) which are not actively regulating the current, they reduce the current drawn by LEDs in their series, but lowering the Voltage will lead to decreasing the current, and what is worst, increasing the voltage will lead to overcurrent/overheating the LEDs, causing very quick deadth...with resistors, there is simply no active current regulation with almost no protection at all.
Lets have a look on few graphs showing Brightness vs Voltage dependency for Constant Voltage system LED strips :
Diagrams on the graph shows 12V LED strips (left 2 shapes) and 24VDC LED strips (right 3 shapes) explains :
both STANDARD LED strips contain only resistors, thus their brightness (Y-axis)is increasing almost in linear with increasing Voltage (X-axis), until the LEDs are overheated due to overpower, then their brightness falls starts to decrease and the LEDs die. Low power LEDs (12V Standard LED strip on left) are not able to heat up the LED strip that much, but running them above their "maximum allowed current" leads to failure anyway.
MASTER LED strips contain CC IC (Constant current IC / driver) which is basically doing nothing until the Voltage "Umin" is reached where the current will reach a value set on the driver. At this point the brightness is 100% and any other Voltage increase will not impact the brightness of LEDs, as the CC IC driver will actively keep the current to the value where it is set. Thanks to this active current regulation, it is possible to power up the MASTER LED strips not only with Utyp (Typical Power supply say 24VDC) but with Utyp2 ....all the way upto Umax...explained more in depth bellow .
Red area shown on the graph is basically "prohibited area" for the STANDARD LED strips (with only a resistors and LEDs)
MASTER LED strips are working always OK even at these areas (no overheating, no overcurrent, no overpower, no lifetime and light decay, etc)
Graph "Allowed Voltage drop limits" shows the range of allowed Voltage where the LED strips are working OK (and with even and 100% identical brightness)
Lets focus on 2 comparisons :
12V vs 24V LED strips
Allowed voltage range within each Voltage system
12V vs 24V showsfor both STANDARD LED strips (with resistors) almost identical Voltage range (red and blue continuous part of graph shapes)...As you can see , no 2 LEDs on the strip will have identical brightness, as they will never have identical current....as the voltage changes due to resistance (on wires and LED strip itself), it continuously "reduces the brightness" ... a range of 90%-110% is agreed as "allowed" for this kind of LED strips...the size of continuous shape is small (normally you must use thick wires, and short distance, to limit the Voltage drop outside of the LED strip to minimum....otherwise your LED strip will never reach power output nothing close to 100% )
In oposite these basic STANDARD LED strips (with resistor only) our MASTER LED strips with constant current drivers (CC IC) have their limits several times better, allowing them to be 100% bright (for example MASTER-LONGRUN is 100% bright when Voltage is anything between 17.5V upto even 36VDC )
When powering these LED strips from 24VDC you can easily count with Voltage drop on wires + LED strip itself upto 6.5V! (24V-17.5V=6.5V) As many power supplies have ability to "increase its output voltage " by 10-15% to cover the Voltage drops on wires, you can be sure that they will be never overheated and their lifetime will be identical as if powered from 24V or 21V ...does not matter.
Voltage range vs max. allowed installed length explained
Graph is showing two different 24VDC LED strips only :
STANDARD LED strip (with resistor and LEDs only) with no active current regulation
MASTER-LONGRUN LED strip with constant current drivers (specific LED strip focused on very long installed distances)
Red continuous line (STANDARD LED strips) have only short area between limits (Umin and Umax) thus their maximum installed length is very small (red bar graph in top part - 5-10m normally)....causing you to use many power supplies along any longer line that that.
Oposite that, MASTER-LONGRUN LED strip with constant current drivers have very wide gap between its limits (Umin and Umax) allowing to use much higher Voltage drop on wires with no effect on brightness. As this is possible, you can use so much of LED strip in one line, until it will reach one of its 2 limits :
Umin - bellow this Voltage limit the LED strip will start to decrease its brightness, as there will be not sufficient amount of voltage to open LED's PN junction with sufficient current. When powered from 24VDC, you will reach this Umin limit with about 30m of LED strip in single line (Umin will be on its far end).
max. allowed current path - where Utyp2 comes into play (bellow)
Are interested what is the Umax parameter? ...Umax is maximum allowed Voltage, exceeding which a permanent damage to the LED strip will ocur. As you can see, Umax for all our MASTER LED Strips is 36V, which is far enough from Utyp (24V) or from extended Voltage Utyp2 (30V) so you can have peace in mind, that the LED strip will be safe. When using long or thin input wires to power up the LED strip, this extra space can be used for Voltage drops which are inevitable. So you have additional 5-6V for voltage drops on input wires! Never exceed !Umax! otherwise it might lead to permanent damage.
Utyp2 - when you need to install even longer lines than "Dmax @Utyp "(30m for LONGRUN design will draw only 3000mA from Power supply ) and as our current limit for MASTER-LONGRUN design is massive 7000mA we are using only almost half of its "max. current" limit" ! Simply increase the voltage (LONGRUN upper Voltage limit Utyp2 to reach "Dmax @Utyp2" is 30V) which will allow you to use full limit of max. 7000mA current path resulting in max. 140m of LED strip (powered from the middle)!.... and all 8400 LEDs on whole 140m of line will be bright to 100% , no more, no less.