PTN3460I dark screen in -10dC environment

[amos_hc_chen]

Hi Sir,

This is Amos from Delta Electronics,Inc.
We get an issue from our customer when operating in -10dC environment.
Seems sometimes PTN3460 does not start properly, the LCM shows dark screen because PVCCEN is LOW level. After the system warm up, PTN3460 can start properly. This issue is temperature dependent.
We capture the waveform, PTN3460 PVCCEN is turned on about 100ms then turned off.
When dark screen condition, BKLTEN and LVDS are no signals. But eDP (main link and AUX) signals are not loss. We can read PTN3460 internal register by SMBus and FW version by AUX. PTN3460 still alive.

Is it any thing caused PVCCEN turned off?

PTN3460IBS/F2 (DC 1735)
CPU: Baytrail-I E3845
OS: Win7 Embedded

System Topology:

CPU E3845 (eDP) => PTN3460 (LVDS) => LCM

[amos_hc_chen]

Hi Sir,

Update the DPCD registers value for OK and NG (dark screen).

Thank you.

Amos.

[guoweisun]

Hi

Can you provide the schematic? Can you confirm this failure part work well in normal temperature?

Can you cross change the IC of PTN3460I from the good board to bad board then check again?

Or cross change the IC of PTN3460I from bad to good board to check!

Does not customer  mix the PTN3460 or PTN3460I?

[amos_hc_chen]

Hi Guowei

I send  the schematic by mail due to the confidential.

Yes, the failure part work well in normal temperature. I duplicated the dark screen case in my lab and the IC is PTN3460I. Did you here the same failure case in PTN3460?

Do you have any advice about this issue? What DPCD rigisters we need check?

 I tried to cross change PTN3460 on different PCB, it is difficult during the rework. I still tried this.

Thank you.

Amos.

[guoweisun]

Hi

Please notice that PTN3460 can't support -10C but PTN3460I can do that!

If DP source  doesn’t send video to the PTN3460I, so that PTN3460 doesn’t drive PVCCEN pin to high.

For the DPCD you can check the 0X600,0X701 for checking SET_POWER DPCD register and EDP_GENERAL_CAPABILITY_REGISTER_1 DPCD register.

[amos_hc_chen]

Hi Guowei

Could you give me the register define for 0X701?

Thank you.

Amos.

[guoweisun]

Hi Amos

 The DPCD registers are define by VESA

You can refer to below link for more detail about 0X701content:

https://www.docin.com/p-2144828688.html 

[amos_hc_chen]

Hi Guowei

Here are the partial schematics.

Please keep in confidential.

Thank you.

[guoweisun]

Please delete these SCH for confidentiality!