0ohm resistor, why?

Other Hardware General Electronics
1

Why people use 0ohm resistors? Is there any application that might be useful for that?
Doesn't a wire do the same?

2

Because wire doesn't come in standard sizes that can be handled by pick and place machines.

3

AWOL:
Because wire doesn't come in standard sizes that can be handled by pick and place machines.

Well but you can cut it short.
So this means it works like a wire?

4

Yes, just like wire.

5

There are 2 scenarios where 0? resistors are commonly used:

  1. Jumpers and links in through-hole boards. They can be placed automatically by machines designed to handle resistors, so you don't need one specially set up to handle wires.

  2. "optional" resistor settings in surface mount (and through hole, I guess) boards. For instance, I sell LED boards - 8 LEDs on a PCB with current limiting resistors. By default they are set up for 5V usage. Sometimes someone wants one for 3.3V usage, so I reduce the resistor. Sometimes someone wants them for a constant-current source, so they want no resistor. In that scenario I use a 0? resistor. The same may apply for any board where the exact arrangement of components may vary depending on a customer's needs.

6

Sometimes they are used for current-measuring during development - a small
value resistor is used in test boards so the current can be measured. Production
boards substitute a 0 ohm part.

Another reason might be to route a trace on a crowded two-layer board.

7

Zero ohm resistors are used a lot by risk averse professionals to:-

  1. Make the provision for a series inductor in a decoupling circuit if needed.
  2. Allow alternative modules to be patched in if needed.
  3. Allow extra decoupling to be patched in if needed

By allowing flexibility like this more work can be done on one prototype PCB revision, and it is that which costs both time and money.

8

understood, thank you guys

9

and the only situation where, if both resistors are 0R0, two resistors in series is the same as two resistors in parallel ie R1 + R2 = R1 x R2 / (R1 + R2) which equates to R12 + (2 x R1 x R2) + R22 = R1 + R2

Wot a load of rot :smiley: :smiley: :smiley: