Hi,
I have questions for DQS signal of AM3874.
My customer has DDR3 Read error issue with AM3874 now.
So customer measured the singal of DDR3 DQS and data.
Please see the following the waveform.
Yellow waveform is DQS signal, and blue is data line.
Please notice the red circle. As you see, DQS signal have some small peak on rising and falling edge. These unexpected small peaks never happen on data line. And these small summit on DQS is not made by the influence of data line Because small peaks happens when the data is "0".
I think DQS is important for reading data by AM3874. So this small peaks should not be expected on DQS signal.
My question is the below.
1) DQS and data is patterned on the board by the same topology. But each waveform is big different. According to my understanding, the termination logic of DQS and data signal is the same. Is my understanding right? Or is DQS the termination logic of AM3874 internal diffrent from Data ?
2) My customer tested to change ODT setting. But it wa not effect for this read error.
Please see the below waveform. You can see ODT setting is no fluence for DQS.
(Please visit the site to view this file)
The small summit on rising and falling edge has never gone. Is the ODT feature effective for DQS?
Please give your adivces to me.
I appreciate your quick reply.
Best regards,
Michi