DS280MB810: Termination, Power Down, Mute Output, HI-Z

Nikita Alisov

Prodigy 140 points

Part Number: DS280MB810
Other Parts Discussed in Thread: TDP2004

Tool/software:

Hi,

Could you please clarify a few points about DS280MB810:

1. Termination.

There is mention that DS280MB810 has input 100 Ohm termination, but I could not find how exactly termination is connected. If it is connected to some Vbais source, what is the level of the Vbais?

2. Power Down

I can see "Driver and equalizer power down manually with Reg_0x06[3] and Reg_0x04[3]." And that Reg_0x06[3] has two options: "Power down the driver", "driver power on/off is controlled by signal detect". For me it looks like there is a capability to force a Channel to the off stage, but

2.1 Can I force that Channel to "on" stage without controlling by signal detection?

2.2 What is the input impedance of the powered-down channel? (Is the capability to force the inputs to the HI-Z stage?)

3. Mute Output

There is the capability to manually mute the driver output.

3.1 What is the input impedance of muter output? (Is the capability to force the outputs to the HI-Z stage?)

Regarding points 2 and 3, I just trying to understand if I can get/manage the HI-Z state of input/output in some way. Can I?

Thank you

BR
Nikita

over 1 year ago

0 Nasser Mohammadi over 1 year ago

TI__Guru* 93670 points

Hi Nikita,

As we discussed, please consider TDP2004 for this application. Once you review this data sheet, please let us know if there is further question.

Regards, Nasser

0 Nikita Alisov over 1 year ago in reply to Nasser Mohammadi

Prodigy 140 points

Hi Nasser,

Yes, I know about TDP2004/TDP2044xxx, and I have EVB, and it looks lovely, but I still have tasks when I need a device like DS280MB (not only, but for DP as well). I am currently trying to see if I can use a single DS280MB in those tasks or if I must use additional DP re-drivers. So, answers to the questions are still relevant and would be really helpful.

+1 Lucas Wolter over 1 year ago in reply to Nikita Alisov

TI__Mastermind 28100 points

Hi Nikita,

1. Regarding Rx termination structure, I don't immediately have an answer if Rx pins are connected to some Vbias source. Are you asking to check if a Vbias voltage will conflict with the common mode voltage of your transmitter? DS280MB810 has integrated AC coupling on its receiver which blocks any DC voltage from reaching the device.

2. Yes, a channel can be force enabled by forcing signal detect result to 1. This can be done by writing channel register 0x05[7]=1.

Regarding input impedance when the channel is powered down or output is muted, I don't immediately have an answer. Allow me to check internally and get back to you.

Best,

Lucas

0 Nikita Alisov over 1 year ago in reply to Lucas Wolter

Prodigy 140 points

Thank you Lucas! I got it and will wait for your updates, thank you!

+1 Lucas Wolter over 1 year ago in reply to Nikita Alisov

TI__Mastermind 28100 points

Hi Nikita,

Receiver inputs are terminated to a weak bias voltage. Since the receiver pins are internally AC coupled, this bias voltage is blocked and does not reach outside the device. Here is a simplified diagram which shows the termination structure.

When the channel is powered down or output is muted, input impedance remains at 100 ohm differential.

I understand you are evaluating if DS280MB810 can be used in a DP application. Are there any other use cases you are considering using DS280MB810 with?

Best,

Lucas

0 Nikita Alisov over 1 year ago in reply to Lucas Wolter

Prodigy 140 points

Hi Lucas,

Thank you for the response, now it's clear.

>>> Are there any other use cases you are considering using DS280MB810 with?
Some USB-C solutions up to 10/20 GHz.

0 Nikita Alisov over 1 year ago in reply to Lucas Wolter

Prodigy 140 points

Could you clearify anoter point regarding input/output return losses:

Unfortunately, it's not clear to me:
- What data should I use to estimate RL at 10 GHz? I suppose it should be somewhere between -12 and -8, but... how much?
- How should I understand data that is given like "typicaly no more than..."? Does it mean -8 dB for 10 GHz is the worst case? If not, what is the worst case for 10 GHz?

0 Lucas Wolter over 1 year ago in reply to Nikita Alisov

TI__Mastermind 28100 points

Hi Nikita,

Please note that we have a broad portfolio of redrivers and muxes which are better suited for USB-C than DS280MB810.

https://www.ti.com/interface/usb/redrivers-multiplexers/overview.html

Allow me to investigate return loss values internally and get back to you.

Best,

Lucas

+1 Lucas Wolter over 1 year ago in reply to Lucas Wolter

TI__Mastermind 28100 points

Hi Nikita,

I discussed return loss with our validation team and found that the return loss at 10 GHz is ~ -8 dB.

Best,

Lucas

0 Nikita Alisov over 1 year ago in reply to Lucas Wolter

Prodigy 140 points

Hi Lucas,

Thank you for the confirmation of the value. Let me ask what is the type of the value. Is it typical RL, or is it max RL.
If -8 dB is typical, how could I estimate max RL?

+1 Lucas Wolter over 1 year ago in reply to Nikita Alisov

TI__Mastermind 28100 points

Hi Nikita,

This is max RL spec.

Best,

Lucas

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DS280MB810: Termination, Power Down, Mute Output, HI-Z