Zero Ohm Resistors – Calculating Maximum Current


According to Ohm's Law, if the resistance is zero, the power dissipated by a resistor is unmeaning.

$$P_d = R \times I^2$$

$$I = \sqrt{ \frac {P_d}{R} }$$

Can one calculate the resistance given that power is defined? Only by knowing power, how can one calculate the maximum current of a zero-Ohm resistor?

I'm a bit confused as I've seen there is zero-Ohm resistors with specified power in the market.

Best Answer

The power rating (and the tolerance) of a so-called 0\$\Omega\$ resistor is sort of vestigial- it comes from the series of resistors that the jumper resembles.

The actual current rating does not necessarily represent the same power dissipation as a similar resistor (the limit may be something like current density rather than power dissipation). For example, the Rohm MCR03ERTJ000 is part of the MCR03 series rated at 100mW, but the jumper version is 50m\$\Omega\$ maximum and rated at 1A max, so only 50mW.

enter image description here

So, it is not valid or safe in general to calculate the current rating, you should look it up in the data or contact the manufacturer, especially if high peak currents will occur, or your jumper could act as a fuse.