DS90UB954-Q1: Link status during shorted RIN pins

Tomoaki Yoshida91

Genius 5255 points

Part Number: DS90UB954-Q1

Hi team,

Please tell me the Link status when RIN pin is shorted.

We use 953 and 954 with differential signals.

If either RIN + or RIN- is shorted at this time, what is the link status?

1. Rin+ (or -) is shorted to GND

2. Rin+ (or -) is shorted to VDD

In this case, it looks like a single-ended input, but will FPD-LINK lost link?

Or will the link continue depending on the conditions?

3. Rin + is shorted to Rin-

In this case, there is no signal, so the link is always lost.

Is this correct?

Is this the same with the 953 DOUT?

Best regards,

Tomoaki Yoshida

over 5 years ago

0 Hamzeh Jaradat over 5 years ago

TI__Guru** 107820 points

Hello Yoshida,

If Rin+ (or-) is:
Shorted to GND, No functionality on the port. The device may get some damaged.
Shorted to VDDx, No functionality on the port. The device may get some damaged if shorted to 3.3V.
Shorted to each other, No device damage but no functionality.

0 Tomoaki Yoshida91 over 5 years ago in reply to Hamzeh Jaradat

Genius 5255 points

Hi Hamzeh-san,

Thank you for your support.

I understand that link is lost in each situasions.

In the situation that shorted to each other, it should be detected with a 954 cable fault.

Is there a way for the user to know that 1 and 2 are short-circuited?

Best regards,

Tomoaki Yoshida

0 Tomoaki Yoshida91 over 5 years ago in reply to Tomoaki Yoshida91

Genius 5255 points

Hi Hamzeh-san,

>Shorted to VDDx, No functionality on the port. The device may get some damaged if shorted to 3.3V.

You answered 3.3V here, but is it the same even if RIN0+ (or RIN0-) is shorted to 1.8V?

Does that mean your answer applies to both 953 and 954?

Best regards,

Tomoaki Yoshida

0 Hamzeh Jaradat over 5 years ago in reply to Tomoaki Yoshida91

TI__Guru** 107820 points

Hello Yoshida-san,

The device will detect the short between Rin+ and - as Cable fault, but there is no option to differentiate which type of cable fault exactly.

To your second question, if shorted to 1v8 this will not cause device damage. Rin pins have an absolute max voltage rating of 2.75V. See 954 d/s page 9.

For 953 you will have damage even if VDD=1.8V since the absolute max is 1.2V.

0 Tomoaki Yoshida91 over 5 years ago in reply to Hamzeh Jaradat

Genius 5255 points

Hi Hamzeh-san,

Thank you for your support.

I understand that the only way to know that something happened is by losing LOCK, when RIN0+ or RIN0- is shorted to GND or Power.

It was very helpful for studying countermeasures.

Best regards,

Tomoaki Yoshida

0 Hamzeh Jaradat over 5 years ago in reply to Tomoaki Yoshida91

TI__Guru** 107820 points

Yes, your understanding is correct.

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DS90UB954-Q1: Link status during shorted RIN pins