The Calculation of LED driver circuit engineering

Power LED calculated from the known number of
Example: The rated output power of 10W power supply, rated forward current 20mA, 70mW power dissipation under the condition number of led high bay light for sale
 can be configured according to the above formula (ie integer data obtained to take)?

1: For a constant drive mode:

LED number and the number of parallel branch known output from the power supply voltage is calculated each road series

(1) Calculate the number of each branch LED

(2) Calculate the number of parallel branch

Note: VLED value varies depending on light color, with a power supply when the drive LED, in order to control the current, usually requires a series resistor.

Example: a rated output voltage of DC 24V, 10W power supply, with a rated forward current 20mA, power dissipation is 70mW rated forward voltage of 1.8V LED can be configured to do the number (integer data obtained).?

You can slip with 10 groups, each way 14 LED series circuit consisting of a total of 140 LED.

2: For constant current drive mode

Known by the power supply output current and the current value of the LED count and calculate the number of each parallel branch road

The number of branches (1) parallel computing

(2) Calculate the number of branches in series LED:

Example: a rated output current of DC 0.35A, 10W rated power supply, drive power dissipation 70mW, forward current of 0.02A of the LED, can be how to configure?

Parallel count road:

(Integer fetch data obtained)

Each road series with number: Number

That can take 17 groups of 8 LED in series, a total of 136 LED.

Calculation of line losses and line pressure drop

Wire P = I R V = IR Wire

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

Example: led street lights price with a length of 10 meters (positive and negative wires 5 meters), 24AWG of copper wire, through current of 2A, the loss of power and line drop as much?

Electrician check the manual shows: R = 0.737W Wire

V wire = 2 × 0.737 = 1.474V

Wire P = 2 × 0.737 = 2.948W

As can be seen from the above calculations, the line current is large, pay attention to select the appropriate wire section, otherwise the line losses and line drop is quite large.

We only have to fully understand the basic characteristics of LED and LED power supply, in order to properly design and use of LED light sources.