The function of a resistor is to limit current, so the resistance of a current limiting resistor has a direct impact on power consumption. So when we use current limiting resistors, we need to calculate the product parameters. Below is an explanation of the calculation formula and method.
The resistance value of the current limiting resistor has a direct impact on power consumption. According to Ohm's Law and the power formula, the power consumption of a current limiting resistor can be calculated using the following formula:
P=I²×R
Among them:
P is power (unit: watt W).
I is the current flowing through a resistor (unit: Ampere A).
R is the resistance value of a resistor (in ohms Ω).
From the formula, it can be seen that power consumption is directly proportional to the sum of the square of the current and the resistance value. Therefore, if the resistance of the current limiting resistor is increased, the current will decrease, resulting in a decrease in power consumption. On the contrary, if the resistance of the current limiting resistor is reduced, the current will increase, leading to an increase in power consumption.
In practical applications, the selection of the resistance value of the current limiting resistor needs to comprehensively consider the current demand, voltage limitation, and power capacity of the circuit. Choosing the appropriate resistance value can ensure that the circuit operates within a safe power range while meeting the performance requirements of the circuit.
For example, if a circuit needs to limit the current flowing through the LED to 20mA, the power supply voltage to 5V, and the forward voltage of the LED to 2V, the resistance value of the current limiting resistor can be calculated using the following formula:
At this point, the power consumption of the current limiting resistor is:
Therefore, a current limiting resistor with a rated power greater than 0.06W should be selected to ensure the safe and stable operation of the circuit.
