DS15BR401: LVDS output overshoot

Greetings,

1). Please note figure 2 of the DS15BR401 data sheet. This part requires external 100-ohm termination on its input. This part has integrated internal 100-ohm termination.

2). Similarly, please note figure figure 14. On the left hand side, this could be DS15BR401 with its integrated 100-ohm output termination. While on the right this could be DS15BR401 with external 100-phm termination.

3). Please confirm differential LVDS trace is 100-ohm impedance controlled. Ringing and overshoot indicates impedance mis-match.

Regards,Nasser  

hi  expert,

I confrim differential lvds trace is 100 -ohm impedance controlled.

For the one  LVDS overshot ,I don't think it's Ringing,  if something else caused the promblem ,Could you please give some suggestion?

Scope shot shows this is inductive and then there is some sort of RC time constant. Suggestion is to do TDR. I believe there is some impedance discontinuity through  the signal path.

Regards,Nasser

hi  expert，

1. The LVDS overshot reaches 3.3V，

2.A load discharge pull down path can be used on either output (1 kΩ to ground recommended) ，Now customer use 2 KΩ to g ground ,What is the range of resistance to the ground?

3.String 100Ω resistance at the 401 output end, but the waveform does not change，

Could you please give some suggestion?

hi  expert,

The customer uses six DS15BR401 boards,All it is overshot to 3.3V, Whether there is a hardware design source file for reference?