electronics

Consumption of circuit elements 2. advanced led circuit

2020-04-20 - Kiss J Gabor

The advanced led circuit

The basic datas of cirquit

White led 5 mm × 2 pcs (or 4 pcs).

attribute	value	unit	attribute	value	unit
Vsource	9,0	V
VLED	7,2	V	VLED	7,2	V
ILED 1 line	30	mA	ILED 2 lines	60	mA
PLED (P=V×I)	0,216	W		PLED (P=V×I)	0,432	W

Calculating resistor power R60 (v = 1,8V, I = 30mA)

The voltage drop across the resistor: 9,0 V - 7,2 V / 2 = 1,8 V.
The power dissipated by the resistor (P² = V² / R): 1,8<sup>2</sup> / 54 = 0,054 W.

Calculating efficiency (η) with one line of leds

The efficiency according to the layout (P_LED/P_sum): 0,216 / (0,216 + 0,054) = 0,80 = 80,0 %.

Calculating resistor power R30 (v = 1,8V, I = 60mA)

The voltage drop across the resistor: 9,0 V - 7,2 V / 2 = 1,8 V.
The power dissipated by the resistor (P² = V² / R): 1,8<sup>2</sup> / 30 = 0,108 W.

Calculating efficiency (η) with two line of leds

The efficiency according to the layout (P_LED/P_sum): 0,432 / (0,432 + 0,108) = 0,80 = 80,0 %.

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Links:

Simple LED Circuits
LED lighting from 230V mains

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