Tool/software:
At present, a new Pogo interface keyboard for USB2.0 high-speed USB interface is developed. Due to the long USB line of the keyboard, the USB Redriver TUSB212RWBR IC is added. At present, the test eye diagram shows that the configuration resistor of this IC corresponding to DC_BOOST and AC_Boost is adjusted. It doesn't work. It doesn't look like the IC is working. The specific schematic diagram is as follows:
Hi Herbert,
I reviewed this schematic previously, and made a note about the EQ resistors there, which it appears those havent been changed, as well as the net names on the DP/DM lanes. I will attach those here:
"Additionally, it looks like they have a 100KOhm resistor attached to EQ. For starters, while this is outside of the normal range we recommend for EQ pin resistors, this will also set it to EQ3, which we strongly recommend against. This will cause the redriver to boost the edge of the eye diagram with the highest amount possible. This can cause over-compensation, which would cause false disconnects in the signal.
The same applies for the DC_Boost pin. They are using 100KOhm resistors for a voltage divider, while we have our own recommendations. I believe they are trying to set DC boost to level mid, but they don't need these resistors if that's the case. They can leave the pin as DNI.
Outside of these, I did notice the net names for the DP/DM names are different. Since these pins need to be connected under the device so that the USB2 data lanes are not broken, it may be better to keep them as the same net name:
Finally, we do recommend the TUSB216 over the TUSB212, as the TUSB216 has improved performance over the TUSB212 and additional functionality."
Due to the long USB line of the keyboard, the USB Redriver TUSB212RWBR IC is added.
Just to confirm, our USB2 redrivers do NOT boost LS/FS signals, such as those typically associated with a keyboard. Unless the keyboard is a high-speed device, the redriver will not have any effect.
Additionally, I noticed you have a connection to the disable pin. Please ensure that the redriver is held in reset until VCC is stable, and is enabled BEFORE any signals are sent through the data lanes.
Outside of those things, if you could check the CD and ENA_HS pins, as well as the connection of the data lanes underneath the redriver, I would appreciate it.
Thanks,
Ryan
