TDP158: TDP158 not work with pin strap mode

user3830479

Part Number: TDP158

Dear all:

Our customer uesd TDP158 as HDMI redriver. Circuit refer to datasheet Figure46. Only used Pin strap mode, SCL/SDA_CTL not uesd.

but not signal output. can you help check circuit and give some suggest . thanks!SCHEMATIC1 _ TDP158-1114.pdf

over 7 years ago

0 JMMN over 7 years ago

TI__Guru 60870 points

Hi,

Is the input a regular HDMI input? Or an ac-coupled DP++ input? If the input is a standard HDMI input, it is expecting 50 ohm pullups to 3.3V prior to the capacitors in the receiver path of the TDP158.

Regards,
JMMN

0 user3830479 over 7 years ago in reply to JMMN

Expert 1090 points

Dear Jmmn:

Thanks for your support! The input signal come from MSTAR SOC HDMI output. Whether we must pull high 3.3V with 50 ohm? If not, will no signal output from TDP158? thanks!

0 JMMN over 7 years ago in reply to user3830479

TI__Guru 60870 points

Hi,

Yes if it is a standard HDMI output, the MSTAR SOC HDMI is expecting to see 50 ohm to 3.3V pullups before the series capacitor. Do you have access to the I2C registers? If so, we can pull some debug information from there but the issue is likely the lack of 3.3V terminations on the input of the TDP158.

Regards,
JMMN

0 user3830479 over 7 years ago in reply to JMMN

Expert 1090 points

Dear Jmmn:

Thanks! We don't used I2C PIN, and we added 50ohm pullup to 3.3V before the capacitor, but also not signal output, It is very strange! if circuit have any mistake?or HPD have some issue?

0 JMMN over 7 years ago in reply to user3830479

TI__Guru 60870 points

What is the level of HPD in the system when it fails?

Regards,
JMMN

Interface

Interface forum

TDP158: TDP158 not work with pin strap mode