DS25CP114: Would you please tell me about unused pin

michihiro akashi

Part Number: DS25CP114

Tool/software:

Hello, teams

The unused differential input terminals are open (IN2, IN3 below) in our application.
Can you ask tell for advice on appropriate IN2/IN3 pins handling when unused?

Best regards

over 1 year ago

0 David (ASIC) Liu over 1 year ago

TI__Guru**** 177676 points

Hi,

I would tie the unused minus (-) input side to GND and the plus (+) side to VDD through a 3.3K or similar resistor. this will ensure input noise is not propagated into the crosspoint LVDS switch resulting in sub-optimal signaling performance.

Thanks

David

0 michihiro akashi over 1 year ago in reply to David (ASIC) Liu

Prodigy 180 points

Thanks quick reply.
Could you help me about below questions?

Q1. Does the design of open at unused IN2(+/-), IN3(+/-) that cause ESD break the device?

Q2.Does your coment "input noise" contain ESD?

Best regards

0 David (ASIC) Liu over 1 year ago in reply to michihiro akashi

TI__Guru**** 177676 points

Hi,

The unused input can be held at a static level to ensure the outputs do not accidentally pick up or re-transmit any noise from the system.

Thanks

David

0 michihiro akashi over 1 year ago in reply to David (ASIC) Liu

Prodigy 180 points

Hello,Teams

Thank you for your reply. I understand that the device will not be damaged even if unused input pins are left open. Is there any discrepancy in my understanding above? Does it not accept ESD because it has a pull-up circuit built in? If not, please provide more details.

Best regards

0 David (ASIC) Liu over 1 year ago in reply to michihiro akashi

TI__Guru**** 177676 points

Hi,

I am not clear on your question. You want to hold the input at a certain level so the outputs do not accidentally pick up or re-transmit any noise from the system. This is not about ESD protection.

Thanks

David

0 michihiro akashi over 1 year ago in reply to David (ASIC) Liu

Prodigy 180 points

Hello

Unused input pins are usually pulled up or down from the outside, which is a well-known measure to protect devices from ESD.

Unfortunately, we have left the IN2/IN3 pins open in our application.
We are concerned about device failure due to ESD.
Are there ESD protection circuits inside the IN2/IN3 pins?

I would appreciate it if you could answer Yes or No.

best regards

0 Vishesh Pithadiya over 1 year ago in reply to michihiro akashi

TI__Mastermind 39810 points

Hey,

Yes these pins have an internal ESD protection up to 8kV HBM.

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DS25CP114: Would you please tell me about unused pin