Hello,
We have a board from customer, it used TPD12S016 for HDMI out design.
The HDMI controller on the board is Intel Apollo Lake CPU, direct connect CT_HPD pin to VCCA (a 1.8V always on power when system is power off).
My question as below:
Q1. How to control CT_HPD pin? Shall we pull-low CT_HPD when system is power off?
In this case(CT_HPD pin to VCCA), system HDMI display is ok when first time power on. But there's no display when system shut-down then power on.
Measured the HPD_B (pin 10) and 5V_OUT (pin 13) has same abnormal waveform as below.
I tried to open CT_HPD pin when system power off then short to VCCA when system power on. HDMI display is ok.
I think CT_HPD pin should not connect to a always power rail when system is power off.
Can you help to provide your opinion for the issue?
Q2. For SCL_A & SDA_A, internally with pull-high 10K resistor.And VIL maximum voltage is 0.082xVCCA(0.082x1.8=0.1476V).
If SCL_A & SDA_A has external pull-high 2.2k, will caused DDC channel hand-shake fail?
Thanks!
