TMDS442: Reference schematics

Kishan M S

Prodigy 160 points

Part Number: TMDS442
Other Parts Discussed in Thread: HD3SS215

Please share a reference circuit for 1 in 2 out hdmi using tmds442.

over 6 years ago

0 Brian Zhou over 6 years ago

TI__Guru*** 144195 points

can you use HD3SS215? we have reference schematic for this device.

0 Kishan M S over 6 years ago in reply to Brian Zhou

Prodigy 160 points

Hi, I already have TMDS in stock. Attached is the pdf for two different test boards. If you have any comments on this then please share and will be helpful.tb.pdf END_SCH_REVA_31DEC2018.pdf

0 Brian Zhou over 6 years ago in reply to Kishan M S

TI__Guru*** 144195 points

you may need some pullup resistors on DDC pins

0 Kishan M S over 6 years ago in reply to Brian Zhou

Prodigy 160 points

Yes, that was missing in first schematics and i added pullups in TB but still when powered up TMDS(With only required channel selection resistors mounted) will heat up and do nothing.4578.tb.pdf

0 Brian Zhou over 6 years ago in reply to Kishan M S

TI__Guru*** 144195 points

was logic correct? does HPD goes high on that path?

0 Kishan M S over 6 years ago in reply to Brian Zhou

Prodigy 160 points

I Hope logic is correct. Am testing it with Odroid XU4 and a 720P display. when connecting directly everything is working fine but when connecting through this test board then nothing is coming. Also i checked HPD and it always low when connecting to this board. I checked the pinout of HDMI connector and footprint many times and the TMDS442 pinout and everything is correct. In layout, all the traces are short and i think probability of length matching issues are very less. TMDS442 is powered up with 3.3V using a 1117 3V3 and when powered up TMDS is heating up very high. I tried changing TMDS and still heating up. Is it normal that TMDS442 will heat up when just a sink or source is connected? I can attach some photos of board if you can take a look.

0 Brian Zhou over 6 years ago in reply to Kishan M S

TI__Guru*** 144195 points

something is not right if HPD always low, you may need to add pullup on SCL_sink, SDA_sink as well.
how do you control GPIO pins? can you get pin status like page 22 on datasheet?

0 Brian Zhou over 6 years ago in reply to Brian Zhou

TI__Guru*** 144195 points

did you solve the issue?

0 Kishan M S over 6 years ago in reply to Brian Zhou

Prodigy 160 points

No, Problem is still there. I connected I2C pins with 3.3K pullups to 3.3V. And GPIO connections are as given below.

GE = 3.3V

OE1 = 0V

SA1 = SA2 = 0V

I2CEN1 = 3.3V

PRE1 = 0V

and OVS = Floating, VSADJ = 51

HPD is not getting high after connecting to this board. But the monitor works fine when connecting directly to video source. Also is it normal that TMDS442 heats up around 50 C?

Attached are the images of two different splitter board.

0 Kishan M S over 6 years ago in reply to Kishan M S

Prodigy 160 points

VSADJ = 4.64K *

0 Brian Zhou over 6 years ago in reply to Kishan M S

TI__Guru*** 144195 points

assume SA1 = SA2 = Low, SB1 = SB2 = Low, OE1 = OE2 = Low, I2CEN1 = I2CEN2 = High, SP=low, 5v_pwr1=high?

0 Kishan M S over 6 years ago in reply to Brian Zhou

Prodigy 160 points

Hi, tried above case also, still the output is not coming. TMDS442 only heating up. Is it normal that TMDS442 heats upto 40 to 50? Also its taking around 120 to 150mA @ Vin = 3.32V and 5v_pwr1 = 4.9V