[EZ-USB FX3] Series termination resistors on GPIF lines

[JeCl_4704641]

Hello,

According to the Application Note AN70707, it is recommanded to use 22Ω series terminaison resistor on GPIF lines.

1) Does this only apply to DQs? Or does this apply to DQs and CTLs?

2) In the context of the miniaturization of the PCB, I was wondering if it would be possible to remove these resistors. Especially if we use a "low" frequency (between 1MHz and 10MHz) instead of the maximum allowed frequency (100MHz). Can we dispense with these resistors at low frequencies? Or are they strongly recommended whatever the frequency used? 

Thank you.

Jean.

[Rashi_Vatsa · Accepted solution]

Hello Jean,

1) Does this only apply to DQs? Or does this apply to DQs and CTLs?

>> We recommend 22 ohm series resistors  on all GPIF lines.

2) In the context of the miniaturization of the PCB, I was wondering if it would be possible to remove these resistors. Especially if we use a "low" frequency (between 1MHz and 10MHz) instead of the maximum allowed frequency (100MHz). Can we dispense with these resistors at low frequencies? Or are they strongly recommended whatever the frequency used? 

>> 22-Ω series resistors are recommend to avoid the reflection phenomenon  impedance mismatch of GPIF lines and also due to PCB stack up. Hence, we recommend using 22-Ω series termination resistors to avoid reflection on these lines.