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SamGibson ♦
SamGibson ♦
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I know that if an LEDs are to be connected in a parallel circuit, a resistor must be added to limit the current rate flowing through them. But let's assume that I have blue LEDs with rated forward current of 40 mA and these are connected parallel to 3V power supply. IV curvature shows that for 40 mA it is required forward voltage of 3V, which means that in such a case there is no need for additional resistors, right?

enter image description hereTypical IV curves for various colours of LEDs.

Source: LEDnique - IV curves

Also, if LED have nearly zero resistance, then in case if we add resistor in series with an LED, there will be no voltage drop across LED (all voltage will drop across resistor). As result you cannot reach voltage drop across LED that is greater than forward voltage and current won't flow through it, isn't it so?

enter image description hereFor low-voltage applications a single resistor per LED prevents current hogging by the LED with the lowest Vf

Source: LEDnique - Parallel LEDs – the problem

I know that if an LEDs are to be connected in a parallel circuit, a resistor must be added to limit the current rate flowing through them. But let's assume that I have blue LEDs with rated forward current of 40 mA and these are connected parallel to 3V power supply. IV curvature shows that for 40 mA it is required forward voltage of 3V, which means that in such a case there is no need for additional resistors, right?

enter image description here

Also, if LED have nearly zero resistance, then in case if we add resistor in series with an LED, there will be no voltage drop across LED (all voltage will drop across resistor). As result you cannot reach voltage drop across LED that is greater than forward voltage and current won't flow through it, isn't it so?

enter image description here

I know that if an LEDs are to be connected in a parallel circuit, a resistor must be added to limit the current rate flowing through them. But let's assume that I have blue LEDs with rated forward current of 40 mA and these are connected parallel to 3V power supply. IV curvature shows that for 40 mA it is required forward voltage of 3V, which means that in such a case there is no need for additional resistors, right?

Typical IV curves for various colours of LEDs.

Source: LEDnique - IV curves

Also, if LED have nearly zero resistance, then in case if we add resistor in series with an LED, there will be no voltage drop across LED (all voltage will drop across resistor). As result you cannot reach voltage drop across LED that is greater than forward voltage and current won't flow through it, isn't it so?

For low-voltage applications a single resistor per LED prevents current hogging by the LED with the lowest Vf

Source: LEDnique - Parallel LEDs – the problem

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tomass
tomass
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LEDs in parallel with no resistors

I know that if an LEDs are to be connected in a parallel circuit, a resistor must be added to limit the current rate flowing through them. But let's assume that I have blue LEDs with rated forward current of 40 mA and these are connected parallel to 3V power supply. IV curvature shows that for 40 mA it is required forward voltage of 3V, which means that in such a case there is no need for additional resistors, right?

enter image description here

Also, if LED have nearly zero resistance, then in case if we add resistor in series with an LED, there will be no voltage drop across LED (all voltage will drop across resistor). As result you cannot reach voltage drop across LED that is greater than forward voltage and current won't flow through it, isn't it so?

enter image description here