DS80PCI402: Power dissipation

Koshi Ninomiya

Part Number: DS80PCI402

Hi Team,

My customer is evaluating DS80PCI402 under VIN=3.3V & VOD=1.0Vpp on their board. When they measured the IIN, it was around 350mA. So, power dissipation of the DS80PCI402 became 1.16W,
But the electrical characteristics of datasheet of DS80PCI402 shows that the power dissipation is Typ=660mW, Max=900mW under VIN=3.3V & VOD=1.0Vpp.

Q: Are there any conditions or settings that the power dissipation of DS80PCI402 becomes higher than Max=900mW of electrical characteristics of datasheet?

Thank you.

Best Regards,

Koshi Ninomiya

over 5 years ago

0 Brian Zhou over 5 years ago

TI__Guru*** 146535 points

how they measure IIN?

0 Koshi Ninomiya over 5 years ago in reply to Brian Zhou

TI__Expert 5465 points

Hi Brian-san,

They measured the IIN by measuring output current of 3.3V DC/DC Buck Converter which supplies to the DS80PCI402 only.
Thank you.

Best Regards,

Koshi Ninomiya

0 Nasser Mohammadi over 5 years ago in reply to Koshi Ninomiya

TI__Guru* 93670 points

Hi Koshi-San,

I am thinking this customer may have other components hanging off the 3.3V supply. Would it be possible if this customer uses DS80PCI402 EVM as well. Is this possible? Or can we get this schematic ?

Regards,, Nasser

0 Koshi Ninomiya over 5 years ago in reply to Nasser Mohammadi

TI__Expert 5465 points

Hi Nasser-san and Brian-san,

The 3.3V supply is used to only the DS80PCI402. But the customer found when unused input pins of differential inputs were connected to ground, IIN became higher.
If unused input pins of differential inputs are connected to the ground, does IIN of the DS80PCI402 become higher?
How to handle unused input pins of differential inputs?
Thank you.

Best Regards,

Koshi Ninomiya

0 Nasser Mohammadi over 5 years ago in reply to Koshi Ninomiya

TI__Guru* 93670 points

Hi Koshi-San,

We can AC couple and then connect through 49.9-ohm to ground.

Please check the state of RXDET and PRSNT*. Do we observe high current when RXDET is float and PRSNT* is low?

Regards,, nasser

0 Koshi Ninomiya over 5 years ago in reply to Nasser Mohammadi

TI__Expert 5465 points

Hi Masser-san,

I told the customer how to handle unused input pins.

They set as follows,
- RXDET: Pulled up by 1k-ohm
- /PRSNT: Pulled down by 1k-ohm
Thank you.

Best Regards,

Koshi Ninomiya

0 Lee Sledjeski over 5 years ago in reply to Koshi Ninomiya

TI__Mastermind 43795 points

Hi Koshi-san,

Unused high speed inputs can also be allowed to float. An internal signal detect circuit will keep the unused channel outputs muted.

Regards,

Lee

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DS80PCI402: Power dissipation