DS90UH948-Q1: LVDS output signal quality

Roy Chou1

Part Number: DS90UH948-Q1

Hi Team,

If the display could output the video normally, does it mean that our FPD-link signal is ok to let 948 decode into LVDS signal?

Have you ever heard that the customer measured the LVDS signal(948 LVDS output pin) quality before?

Below is the CLKOUT waveform. Is the square line normal?

Regards,

Roy

over 4 years ago

0 Aaron Heng over 4 years ago

TI__Mastermind 38000 points

Hi Roy,

The ringing artifact could come from the reflection of your board which mean you might have some stub along your high speed routing.

Aaron

0 Roy Chou1 over 4 years ago in reply to Aaron Heng

TI__Genius 16505 points

Aaron,

If I measure the pinout directly, does it have reflection issue?

Roy

0 Aaron Heng over 4 years ago in reply to Roy Chou1

TI__Mastermind 38000 points

Hi Roy,

Yes. It depends where you tap the probe on the board. You will get the reflection if you measure the signal directly on the discrete component.

Aaron

0 Roy Chou1 over 4 years ago in reply to Aaron Heng

TI__Genius 16505 points

Aaron,

Sorry that I still confised. If my probe is connected to 948 pin36/37 directly, does the (CLK)signal waveform include the reflection effect?

Because as my understanding, the signal from 948 pinout is the most robust and the signal should be good.

Regards,

Roy

0 Aaron Heng over 4 years ago in reply to Roy Chou1

TI__Mastermind 38000 points

Hi Roy,

If that the case then it is more likely coming from your board.

Aaron

0 Roy Chou1 over 4 years ago in reply to Aaron Heng

TI__Genius 16505 points

Hi Aaron,

May you let me know how to prove that the affect is from board instead of IC?

Roy

0 Aaron Heng over 4 years ago in reply to Roy Chou1

TI__Mastermind 38000 points

Hi Roy,

You may want to measure the TDR on the board as well as the cables. Note that when you measure TDR onboard, you must exclude the cable. Basically, in order to get a proper measurement, you need to use the probe landing on the pad from the connector to the device. You can measure the TDR with or without device.

Aaron

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DS90UH948-Q1: LVDS output signal quality