TFP401A: Hsync output is fixed to Low, DE output is fixed to High.

Hiroaki Yuyama TED

Part Number: TFP401A
Other Parts Discussed in Thread: TFP401

Tool/software:

Dear, Technical support Team.

Our customer has connected the TFP401A to an HDMI receiver.
The technical problem is that DE (Data Enable) and Hsync are fixed values.

This is the output state of the TFP401A.
・CLK output is normal (no disturbance at about 74MHz)
・Vsync output is normal (periodic pulses are output without disturbance)
・Hsync output is fixed at low and abnormal
・DE output is fixed at high and abnormal
・SCDT is fixed at high

When using a TFP401A with an HDMI receiver, does this happen (DE and Hsync are fixed)?
Also, if you know the settings to output DE and Hsync, please let me know.

As customer information, when connecting a Sony camera to a board equipped with an Analog Devices HDMI receiver instead of the TFP401A,
we were able to confirm that both Hsync and DE have normal (periodic and undisturbed, reasonable) pulse waveforms.

Best Regards,
Hiroaki Yuyama

22 days ago

0 Vishesh Pithadiya 21 days ago

TI__Genius 13590 points

Hey Hiroaki,

No this is not normal behavior for the device. Can you send the pin config & schematic you are using? Does this happen when the TFP401 chip is swapped?

0 Hiroaki Yuyama TED 15 days ago in reply to Vishesh Pithadiya

Expert 1390 points

Hi Vishesh-san,

Thank you for your reply and support.

We received a circuit schematic from a customer.
Our FAEs at Disty have checked the schematics and connections and power decoupling. Please check it yourself and let us know if there are any issues.
Also, although I haven't swapped the TFP401A, the same problem is occurring on multiple boards.

Best Regards,
Hiroaki Yuyama

0 Vishesh Pithadiya 15 days ago in reply to Hiroaki Yuyama TED

TI__Genius 13590 points

What is the status of the SCDT pin when you see the abnormal waveforms?

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TFP401A: Hsync output is fixed to Low, DE output is fixed to High.