About Zero Ohms resistors

Soldered jumpers.

Jon

Convenience.

You could use wire links too but not all auto-insert machinery is set up to do this.

On the SMD level a zerohm link is the only option.

Widely used to avoid requiring a 2 layer pcb.

Graham

I use them for "I might need a resistor here". For example, in one of my current designs I've got four 0603 footprints forming a "plus" on each I/O port (the wires run across the house, lots of EMI issues, etc) - one from the driver to the common point, one from power to the common point, one from ground, one from the common point ot the terminal block. That way, I can wire it up for whatever type of filter (RC, termination, 1wire pullup, etc) I need. Zero ohm resistors would be used when no resistance was needed.

VCC | [ ] [ ] | driver ----[] []---+---[] []---- terminal | [ ] [ ] | GND

You can also use them to disconnect parts of the circuit from each other, either for debugging or for alternate designs. Sort of a hard-wired SPST or SPDT switch.

Super conductors for situations when you need infinite current but only have a few volts available ;)

Only in really crappy designs. OTOH, you rarely see a decent design on a single sided PC board.

They have a number of good uses:

1. To configure a board for a particular use.
2. To ground unused inputs.
3. To prevent accident reprogramming.
4. For a Zero dB Pad (Attenuator or gain control) where you eliminate the two resistors to ground, and replace the series resistor with Zero ohms for a direct connection.

It's just a jumper. The thing is, a little piece of wire won't fit in the claw of a pick-and-place machine. They don't want to assemble by hand, so the wire gets a little epoxy jacket to make it fatter.

to replace the solder blob, hope I speel it correct :)

jumpers?