TPS23881: questions for TPS23881 applications

Mark Chen52

Part Number: TPS23881
Other Parts Discussed in Thread: LMR36006,

Hi Expert,

The following are the application requirements of the PSE card.

Customer will use the TPS23881 with 6 MOSFETs and use the LMR36006 apply to VDD. Can you help to check if such a collocation application is ok or not?? thank you.

Regards,

Mark

over 3 years ago

0 Mark Chen52 over 3 years ago

TI__Expert 8225 points

Hi Expert,

Any comments here?

Regard,

Mark

0 Atilla Sulker over 3 years ago in reply to Mark Chen52

TI__Prodigy 150 points

Hello Mark,

Sorry for the late reply.

I will try to get back to you by the end of the day today.

All my best,

Atilla

0 Atilla Sulker over 3 years ago in reply to Mark Chen52

TI__Prodigy 150 points

Hello Mark,

As per the data sheet for the TPS23881 (you can see this here - TPS23881 Type-4 4-Pair 8-Channel PoE 2 PSE Controller with SRAM and 200 mΩ RSENSE datasheet (Rev. D) (ti.com)), "The recommended VDD supply voltage requirement is 3.3 V, ±0.3 V. The TPS23881 requires approximately 6 mA typical and 12 mA maximum from the VDD supply."

As long as the supply falls within this range, I don't see any reason why this would not work. Looking at the datasheet for the LMR36006, it seems that this would be possible - i.e., it would be able to output a voltage that works with the TPS23881.

The following EVM guide shows you how a similar step-down converter is connected to the TPS23881: TPS23880EVM: PoE, PSE, TPS23880 Evaluation Module (Rev. B)

All my best,

Atilla

0 Mark Chen52 over 3 years ago in reply to Atilla Sulker

TI__Expert 8225 points

Hi Atilla,

Thanks for check, could help to check below questions for customer?

1. Are there any restrictions on the allocation of TPS23881 channels? If it is according to the picture below, is it ok?

2. Does the TPS23881 need to be programmed with FW? Is there a limit to the number of times it can be programmed?

Regards,

Mark

+1 Atilla Sulker over 3 years ago in reply to Mark Chen52

TI__Prodigy 150 points

Hello Mark,

Thank you for your note.

The configuration you listed below looks correct. The TPS23881 has 8 channels and supports 4-pair power. You can, of course, combine 4-pair and 2-pair power ports. Recall that a 4-pair connection is two channels, and a 2-pair connection is one channel. So, each 30W port would use 2-pairs, or one channel for each 30W port. And each 90W port would use 4-pairs, or two channels for each 90W port. So, two 1- channel ports and two 2-channel ports = 6 channels. So, your understanding as per the table you attached is correct. One small note – there is a typo on the table. It says “GE 802.3af” for 30W, but in reality, it is the IEEE802.3at standard that supports up to 30W.

To answer your second question, what type of firmware are you talking about? If you are talking about system level software for port power budgeting, the TPS23881 supports FirmPSE, TI’s turnkey, GUI configurable software for power budgeting. It is not required to use FirmPSE with the TPS23881, but it is an option.

This video might help as it discusses the FirmPSE software: Power sourcing equipment | TI.com

Hope this helps.

All my best,

Atilla

0 Mark Chen52 over 3 years ago in reply to Atilla Sulker

TI__Expert 8225 points

Thanks for your feedback, Atilla,

The attachment is the schematic for customer application, could you help to review it.

PSE_0801_power with ti.pdf

The use of the diode in the picture below is different from that of the datasheet and EVM board, please help to check.

Regards,

Mark

0 Atilla Sulker over 3 years ago in reply to Mark Chen52

TI__Prodigy 150 points

Mark,

I will get back to you on this tomorrow.

Best,

Atilla

0 Mark Chen52 over 3 years ago in reply to Atilla Sulker

TI__Expert 8225 points

Hi Atilla,

okay, no problem.

one more question, customer would to know the TI POE solution roadmap, could you share it with me?

Regards,

Mark

0 Atilla Sulker over 3 years ago in reply to Mark Chen52

TI__Prodigy 150 points

Dear Mark,

The solution seems to work, although I am not sure what the purpose of such a diode configuration is - do you know the reason?

What would you like to know about our PoE solutions? We can help you find the right part, but can't share the roadmap.

All the best,

Atilla

0 Mark Chen52 over 3 years ago in reply to Atilla Sulker

TI__Expert 8225 points

Hi Atilla,

Thanks for check, for the diode selection, customer just follow their previous project to design.

TN_204_Design_for_high_energy_surge_immunity_within_PSE_system_rev_0_1.pdf

Attached is reference circuit from customer provide.

Do you think such a design is necessary? Or customer just to follow the EVM board circuit to design, and only use one TVS to achieve the same security. Thank you.

Regards,

Mark

0 Mark Chen52 over 3 years ago in reply to Mark Chen52

TI__Expert 8225 points

any other question, because customer worry about the demand in future, do you have any other suggest solution for customer which can meet customer requirement as well?

Regards,

Mark

+1 Brandon Beader over 3 years ago in reply to Mark Chen52

TI__Genius 15625 points

Hi Mark,

The diode surge protection circuit is not necessary for this design, the TVS diode from EVM circuit design will suffice.

In regards to supply, we can not guarantee any supply at the current moment. What are design needs of the customer (power level, # of channels)?

Very respectfully,

Brandon Beader

0 Mark Chen52 over 3 years ago in reply to Brandon Beader

TI__Expert 8225 points

HI Brandon,

customer didn't feedback to me for their request, i close it first.

thank you.

Regards,

Mark

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TPS23881: questions for TPS23881 applications