Calculate the number of LEDs from known power sources 1: For constant voltage drive mode: Calculate the number of LEDs in series and the number of parallel branches per branch from the known output supply voltage (2) Calculate the number of parallel branches Note: The VLED values ​​vary according to the different illuminating colors. When driving the LED with a regulated power supply, in order to control the current, a series resistor is usually required. 2: For constant current drive mode Calculate the number of parallel branches and the number of each branch from the known power output current and the current value of the LED (1) Calculate the number of branches in parallel (2) Calculate the number of LEDs in the branch: Line loss and line voltage drop calculation P wire = IRV wire = IR Single Burner Electric Hotplate Portable Hot Plate,Single Burner Electric Hotplate,Hot Plates,Hot Plates With Stainless Housing Shaoxing Haoda Electrical Appliance Co.,Ltd , http://www.zjhaoda.com
Example: The rated output power is 10W power supply, using the rated forward current 20mA, how many LEDs can be configured under the condition of dissipating power 70mW? According to the above formula (that is, the integer of the obtained data)
(1) Calculate the number of LEDs per branch
Example: A rated output voltage is DC 24V, power is 10W power supply, rated forward current is 20mA, and the power dissipation is 70mW. The rated forward voltage is 1.8V. How many LEDs can be configured? (Integer of the obtained data)
It can carry 10 groups of branches, 14 circuits of LEDs connected in series for each branch, a total of 140 LEDs.
Example: A rated output current is DC 0.35A, rated power is 10W power supply, drive dissipated power is 70mW, forward current is 0.02A LED, how can it be configured?
Parallel count circuit:
(integer of the obtained data)
The number of serial connections per branch: the number can be set with 17 groups, each group of 8 LEDs connected in series, a total of 136 LEDs.
R wire = σ (Remark: L is the wire length; S is the wire cross-sectional area; σ is the wire conductivity) can also be found in the electrician manual.
Example: With a length of 10 meters (5 meters for each of the positive and negative wires), 24AWG copper core wire, the current is 2A, what is the power loss and line voltage drop?
Check the electrician manual to know: 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 that when the line current is large, it is necessary to pay attention to selecting a suitable conductor cross section, otherwise the line loss and line voltage drop are quite large.
We can only properly design and use LED light sources if we fully understand the basic characteristics of LED and LED power supplies.