what is 0 ohm resistor use for?

0 ohm resistor gnd

Hi.. I have 2 different grounds (digital and analogue grounding) and I'm given a 0 Ohm resistor. Just wondering what isit use for? How can I seperate these 2 grounds?

pcb gnd 0ohm

On 0Ω resistor:


On 2 different grounds:


For more info just search this forum and you will find a lot of interesting opinions ..

Regards,
IanP

analog ground resistor 0-ohm

As you are having two different Ground... Uqite possible that the 0 Ohm resistor is provided to you to just short the the two grounds (if it is only for the testing) so that you donnt have to use different isolated supplies for the testing purpose.

0 Ohm resistor is nothing more than a wire.. which is quite often used to short two different points on the board.

it is usually for a connection that is not always permanent and it is to b switched on/off or it is the junction to check the signal at a specific place

As stated previously, digital signals are usually noisey (due to constant switching) and analog circuits are sensative. Hence, the GND planes are separated.

To seperate the two GNDs, you will need two 0 Ohm resistors. This will give you the option to connect to either/both GNDs.

It can serve as an isolation for high frequency noise since this O ohms are inductive in nature!

It can use as a switcher , when you sold it in the circuit , the swich is on , ot the swith is off

of course you can't separate digital ground and analog ground completely,

otherwise the signal between analog and digital will have no return path.

the circuit will not work.

best regards

shirley_opss said:

Hi.. I have 2 different grounds (digital and analogue grounding) and I'm given a 0 Ohm resistor. Just wondering what isit use for? How can I seperate these 2 grounds?

Click to expand...

A 0Ω resistor is used as a link between two points. Its main reason for being in a resistor package is for automated pick and place assembly lines.

Both Analog ground and Digital ground need to be connected as *close* to the power supply as possible, but *each* analog circuit should run a separate ground line so that volt drops caused by current flow don't impact on other analog circuits

It also avoids ground loops by only connecting the ground at one point in the circuit.

We use zero ohms mostly for option selects.

They also come in handy for later impedance matching, we put them in transmission lines in case they need tuning later, which happens a lot.

Lastly, we use them at each grounded mounting hole on the PCB so the EMI lab can experiment with where the circuit is physically gounded to the chassis. This sounds like what you are running into. The EMI guys can use the pads for capacitors or ferrite beads if needed. EMI is very hard to predict, and those guys can only do a valid test on a product that is almost 100% in it's final form. With uncommited grounds they can figure out which place(es) to ground the board and just change the BOM without changing the board design. It's tricky because ground currents in both chassis and PC Boards are excellent radiators.

Still I didn't understand how 0 ohm helps to isolate between analog and digital gnd.
Can't analog and digital planes can be shorted at one place without 0 ohm? Is any speciality shoring with 0 ohm?

Sorry, bad habit of too much information.

Most likely it was put there as an option where to place the system star ground. If you want to run both grounds to the power supply; don't put it in.

Do you understand the reason for seperate Digital and Analog grounds and grounding in general? My answer won't make much sense if you don't.