Selecting the power supply for Pixel LED project

Power supply for the Pixel LED Project

There are many types of power supplies available today ,It's very important that you choose the correct power supply for your requirements .There are basically two types of power supplies available in the market, Linear power supplies and the Switch Mode Power Supplies (S.M.P.S)

Linear Power supply .

Linear Power supply

It's a power supply that use Linear Transformers to regulate the voltage . Working principle is based on mutual induction . These power supplies have large Transformers (Depending on the output current and voltage ). To convert the AC output of the transformer to DC this power supplies have half or full bridge rectifiers (depend on the type of the transformer) and then smooth that voltage using capacitors.

S.M.P.S (Switch Mode Power Supply )

S.M.P.S

It's a power supply that use special transformers with switching circuit and feedback circuit to regulate the voltage.This type of power supplies uses high frequency switching ,Since it uses high frequency we can reduce the amount of coil turns per winding, Which will reduce the size .The AC supply voltage is converted to a DC voltage using a full bridge rectifier ,Then the primary winding of the chopper transformer switched  in high frequency using a F.E.T  which will cause the secondary winding current flow then that voltage is converted to a DC  using a single schottky diode then the high frequency is filtered using a coil in series then the voltage is smoothed using capacitors . 

For pixel LED projects we use S.M.P.S  instead of linear power supplies for multiple reasons.

  

pros (S.M.P.S)

• High efficiency .
• Small in size .
• less weight .

cons  (S.M.P.S)

• R.F interference on close electronic equipment (LED lamps . other S.M.P.S ).
• E.M.F interference . 

Voltage and Current 

Rating of the S.M.P.S for your Pixel LED project depends on these things -

• Number of LEDs .
• Number of LED controllers .
• LED Layout size.
• Working environment .

Voltage and current ratings of the Power supply .

The voltage rating for LED strings and controllers are usually 5Vdc (This may change with the controller model and Pixel LED string type).contact your seller or the manufacturer for the correct voltage rating .

How to calculate the current rating requirement of the power supply -

Maximum current is taken when a Pixel LED is illuminating at white color. R.G.B values (255,255,255).The current taken by the Pixel LED depends on the type of Pixel LED you are going to use .The current taken by the driver chip can be found in the datasheet .

You can also check the pixel LED current by powering up a single Pixel LED without data and check the current taken by it using a multimeter .Connect the multimeter probs in series with the LED and the power supply ( put the multimeter in Amp scale)

Measuring the single Pixel LED Current 

First ,Lets calculate the current taken by one Pixel LED

Current taken by one Pixel LED

Now ,Lets calculate the current taken by all the Pixel LEDs 

Current taken by total Pixel LEDs

Lets calculate the current taken by the controllers .

Current taken by total Controllers 

Lets calculate the Power supply minimum current requirement .

Power supply minimum current  requirement

Finally , Lets calculate the recommended Power supply current  requirement.

Power supply recommended current requirement

We use 50  as the safety factor which means One Half of the minimum power supply current value is the recommended power supply current .Using the above equations you can calculate the Power supply current requirements .

Power supply network 

If you are doing a large Pixel LED project it's very hard to find a single power supply with large current output capability .Don't worry !, You don't have to use a single Power supply .you can use multiple Power supplies to create the required current rating but make sure to connect the ( - ) or (GND) of all the power supplies together .

Here is a example of multiple controllers with multiple power supplies .

Pixel LED Power supply network

In above example we have 3 power supplies with 40A current output which means together they crate 120A current output .
Here is a example of Pixel LED strings powered by separate Power supplies .

Pixel LED Strings powered by separate Power supplies 

In above example 3 set of Pixel LED Strings are powered by separate 3 power supplies .The fist LED of the string sets are connected to a separate 5V /40A power supplies instead of single 120A power supply .Make sure that the ( -) or the (GND) of every Power supply is connected together.

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