digital output on PCB

[ljy4468]

Hi everyone?

I've seen TI ADS5500 Evaluation board.(pipeline ADC 14bit 125MS/s)
and all digital output, clk output pass through 0-ohm resistor.

why digital signal pass through 0-ohm resistor?
what's the effect?

please tell me why.
thanks in advance.

 

[v_c]

I think the 0-ohm resistor is being used as a placeholder. It is much easier to put 0-ohm resistors (using them as jumpers) when you are using automated pick-and-place machines. Now the reason that they are leaving this as a placeholder is in case there are oscillations on the clock line, they can put some resistance in the 30-50 ohm range to compensate. By oscillations, I mean that if the clock pulses don't look square and if they have some ringing at the rising and falling edges.

Best regards,
v_c

 

[alok_ky]

0 ohm resistor gives an option for it to be replaced by another non-zero resistor, in case there is some SI issues. The non-zero resistor will dampen the non-desired effects on the line.