Hi Team,
I understand that Tx and Rx AC coupling capacitor is series capacitance in Figure36
So, total capacitance (form UTX1P/N to DTX1P/N) is 110nF and total capacitance (form URX1P/N to DRX1P/N) is 132nF.
Is my understanding correct?
Regards,
Kanemaru
Hi David-san,
According to our customer, Host IC has a limit of capacitance.
Therefore, they would like to know the total capacitance of each signal lines.
I understand that total capacitance (form UTX1P/N to DTX1P/N) is 110nF and total capacitance (form URX1P/N to DRX1P/N) is 132nF.
Because, TUSB1044 supports the “USB 3.1 ECN Rx AC Coupling Capacitor Option”.
[“USB 3.1 ECN Rx AC Coupling Capacitor Option” comment]
[My image]
And, I understand that TUSB1002A and TUSB1064 are the same as TUSB1044.
Is my understanding correct?
I’m terribly sorry for confusing you.
I’d greatly appreciate your verification.
Regards,
Kanemaru
Hideto-san
Please see the complete USB connection diagram below.
Per the USB 3.2 spec, the total capacitance for USB signal lines is 75nF-265nF.
For TUSB1002A, TUSB1044, TUSB1046 and TUSB1064, they are all linear driver, so the capacitance (red and green) on both side of redriver is separated from each other. So between host and TUSB1044, and between TUSB1044 and device(capacitance in red color), we will have 220nF capacitance on both TX and RX, within the spec of 75nF-265nF. Some will have 100nF instead 220nF which is still within the spec.
Between the two TUSB1044, we have another set of total capacitance in green color. This is 1/220nF (TX) + 1/330nF (RX optional) = 132nF, within 75nF-265nF spec. Without the optional 330nF on the RX, the total capacitance is then the capacitance on the TX line, which is 220nF. Some system would have 100nF on TX instead 220nF, if there is 330nF optional capacitance on the RX, then the total capacitance is 1/100 (TX) + 1/330 (RX) = 76nF.
Thanks
David
