method of calculating the LED drive circuit engineering details

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 By a known electrical power to calculate the number of LED s

Example: The rated output power is 10W power supply, rated forward current 20mA, power dissipation is 70mW conditions can configure the number of LEDs? According to the above formula (ie, take the data from the integer)

1: For the constant voltage drive mode:

LED number and the number of parallel branch from the known to the output supply voltage of each road series

(1) Calculate the number of each branch of the dimmable led downlights

(2) to calculate the parallel branch

Note: VLED values ??according to different luminous colors vary regulator power LED drive current in order to control the series resistance.

Example: a rated output voltage DC24V, power 10W power supply, using the nominal forward current of 20mA, the power dissipation of 70mW nominal forward voltage of 1.8V. Can configure the number of LEDs? (Whichever is an integer) of the obtained data

With 10 groups of branches, each Road 14 LED series circuit, a total of 140 LEDs.

2: For constant current drive mode

Calculated the number of parallel branch and the number of each road by a known power output current and LED current

(1) Calculate the number of branches in parallel

(2) slip cascading LED number:

Example: a rated output current DC0.35A rated power of 10W power driver power dissipation is 70mW, the forward current is 0.02A of the LEDs, how can we configure?

Parallel count Road:

(Whichever is an integer) of the obtained data

Each road cascading number: the number of

Can take the 17 groups, each group of eight LEDs connected in series, a total of 136 LEDs.

Line losses and the calculation of the line drop

P wire = IRV, wire = IR

R wire = σ (Note: L the wire length; S for the wire cross-sectional area; σ to the wire and electrical conductivity) can also check the electrical manual.

Example: a length of 10 meters (positive and negative wires of 5 m), 24AWG copper wire through the current of 2A , its loss of power and line drop number?

Check electrical manual shows: R wire = 0.737W

V wire = 2 × 0.737 = 1.474V

P wire = 2 × 0.737 = 2.948W

It can be seen from the above calculations, the line current to select the appropriate wire cross section, or line loss and line drop is considerable.

We only fully understand the basic characteristics of LEDs and led rope lighting power supply to the proper design and use of LED light source.