TUSB546-DCI: eDP couldnt input in GPIO mode

Hi Roy,

If you are using I2C mode, then CTLSEL[1:0]. should be set to "10" for 4 lane Displayport mode. You should also be sure that SBU and AUX pins are configured correctly. 

Hi Malik,

Thank you for your comments. May I also check some points of TUSB546(GPIO mode) ?

1. pin 32 connection : do we need to use current limit resistor for HPDIN/RSVD2 pin? and What is suggested level for HPDIN "high" level?

2. If I don't use the AUXp/n to SBU1/2 function, we connected to TX directly, but the wire also connect to SBU1/2, does any risk in SBU1/2 pins? 

3. Do we have noise immunity spec of DP signal input?

4. I saw the sec6.6 in datasheet, could we use voltage to set the EQ level instead of using resitor divider?

Thank you.

Roy

Hi Roy,

Could you give some details on the application? Is a Type-C port or DP/eDP port used? 

1. If you are planning on pull HPDIN into some voltage rather than use a GPIO then you should refer to R_(ENPD), I_IH, I_IL, VIH, VIL specs in section 6.6 DC Electrical Characteristics, 2-State CMOS Input in the datasheet .

2. No risk here. Whys is the switch not being used and how will you account of the swap from the Type-C connector?

3. No spec here.

4. Please refer to the 4-Level VTH specs in  6.6 DC Electrical Characteristics, 4-State CMOS Inputs in the datasheet. Threshold voltages are listed here for the different settings. 

Hi Malik,

Thank you for your comments. We use voltage level to set up the EQ level, but there is some question which are showing as below.

1. This is our setting and result.

2. In datasheet, our frequency set 4GHz, we think that the gain will be a little larger that previous one, but in the result. The gain doesn't change in level 1~11.

And my question are

1. Why level 0~11, the gain is almost the same.

2. for EQ0/1, does it have minimum spec for input(DP signal), if the spec have the value, does EQ level relate to this value?

Regards,

Roy

Hi Malik,

Any comments?

Roy

Hi Roy,

Sorry for the delay I was OOO.

1. The graph provided does not look at the gain only the output swing of the signal. To look at eth gain in dB please convert values in reference to the input signal.

2. Not sure if I understand the question but TUSB546 EQ values for DP lanes are listed in Table 7. TUSB546-DCI Receiver Equalization GPIO Control in the datasheet. Are you asking if there is a minimum input swing for DP signals? Referring to Figure 4. DisplayPort Linearity Curves at 4.05 GHz I would say ~400 mVpp minimum to stay in the "best" linear region of TUSB546-DCI.