Part Number: SN75DP159
Hi Sir,
Our customer meet a problem that monitor will black screen (no display) after toggle on/off the Monitor.
HOST (DP++) ---- SN75DP159 ---- Connector ----- Monitor
But weird thing is... the issue will only happened on 4k60Hz resolution, 4k30Hz will not encountered it.
They did some experiments:
1. Measure the HDMI clock @4k30Hz resolution, toggle on/off the monitor... the clock frequency between input & output no different (all with around 133MHz). (No issue)
2. Measure the HDMI clock @4k60Hz resolution, toggle on/off the monitor... the clock frequency between input & output is different. Input around 133MHz but output only got around 33MHZ (Issue happened)
3. Measure the HDMI clock with bypass DP159 @ 4k60Hz resolution, toggle on/off the monitor... the clock frequency between input & output no different (all with around 133MHz). (No issue)
BTW, all with pin mode... is there any clues that you could share us?
They also do some experiments to avoid the signal issue, but not useful.
1. adjust OE timing
2. Adjust higher VSADJ,
3. Changing EQ_SEL, PRE_SEL,
4. Pull-high the 5V on HPD and remove the pull-down 1k ohm on HPD.
Thanks,
George
