DS90UB927Q-Q1: When ds90ub927q-q1 is turned on, it appears a flower screen, which will grounding PBD and eliminate the phenomenon；

Hi Boer,

For your "flower screen" issue, can it be disappeared after a while? Is the de-ser locked or not in your link? for your questions

1. tPLD is <5ms specified by the chip

2. pls follow up the power supply / PDB recommendation in d/s as below.

9 Power Supply Recommendations
This section describes the power-up requirements and PDB pin. The power supply ramp (VDD33 and VDDIO)
should be faster than 1.5 ms with a monotonic rise. A large capacitor on the PDB pin is needed to ensure PDB
arrives after all the supply pins have settled to the recommended operating voltage. When PDB pin is pulled up
to VDD33, a 10-kΩ pullup and a >10-μF capacitor to GND are required to delay the PDB input signal rise. All
inputs must not be driven until both VDD33 and VDDIO has reached steady state. Pins VDD33_A and VDD33_B
should both be externally connected, bypassed, and driven to the same potential (they are not internally
connected).

regards,

Steven

Of course, if the PDB is NOT stable, the 927 output would be not stable as well, so you can see the issue in the panel.

regards

Steven

Boer,

could you please check what is the "noise" that you are talking? also, what is the R810 and R127?

One point is that if the PDB is NOT stable, pls capture how it is NOT stable. as mentioned, if PDB is toggled, the UB927 would stop the serial output and then the panel has no video.

Rgds,

Steven