TPS23861: Detection and classification of PoE PD not executed in Auto Mode when SHTDWN pin is connected to VDD

Hi Carol,

Thanks for your questions!

I am investigating the solutions on my end. Can you share what the application for your system is and if there is a timeline I need to be aware of. 

Best Regards,

Nate 

I use four PoE channels in Auto Mode - this is the typical solution described in the datasheet. I not understand what you mean by "timeline".

Hi Carol,

By application I meant what kind of technology will this be used for? Cameras, security systems, or things like that. By timeline I meant what is the schedule for the project? Are there any deadlines that I need to know about?

Best,

Nate

We use it in security systems. Prototype was built with chips purcharsed in european distribution. We are ready to production already 6 months, because the TPS23861PW temporary are not available at distributors one spool we purcharsed in chinese source. We should stard production ASAP.

Hi Carol,

I see, thank you for providing that information. I want to clarify a few points.

• The chips purchased from China are the only ones that do not perform detection or classification in auto mode, correct?
• On the chips that don't work properly, when the SHTDWN pin is floating or connected to ground, the chips work the way they are supposed to?

Can you share what equipment you used to test the chips and the testing procedure?

What values are in the Port Power Priority Register? If the Port Power Priority Register was changed to 0, that may explain why they started working. From the TPS23861 data sheet:

Best Regards,

Nate Inkster

"The chips purchased from China are the only ones that do not perform detection or classification in auto mode, correct?"
YES

"On the chips that don't work properly, when the SHTDWN pin is floating or connected to ground, the chips work the way they are supposed to?"
YES.
I have one chinese LAN switch in configuration Semi-Auto (TPS23861 + microcontroller). There the SHTDWN pin is connected to the GND via resistor 4k7.
I replaced chip in the LAN switch to purcharsed in China and everything is ok.

I haven't any evaluation board for testing and don't know what vaule in the Priority Register after power On. I made simple microcontroller board to read EEPROM status by I2C. I wanted to check if bit 7 in the Address Register is set - This bit is set - as default.
The Priority Register is not located in the EEPROM.
I tried do additional reset by temporary connection RESET pin to GND - it does'n matter.

My project use only Auto Mode - there is no microcontroller. When bit 7 in Address Register is set then other registers should be automatically set correctly - Otherwise Auto Mode doesn't make sense.
In my oppinion this is the same problem as in the below thread:

e2e.ti.com/.../4529754

Hi Carol, 

I have a few more questions about your procedure.

At moment of power on, is the SHTDWN pin already grounded, or is it grounded after? 

When VPWR is connected, is Vdd already connected as well, or is it connected after? 

Best,

Nate 

I turn on VPWR and VDD simultaneously. During power-up, the SHTDWN must be connected to GND or floating - only then the classification is started. If I momentarily connect the SHTDWN pin to VDD the classification turns off immediately and will not start until power is restarted

If SHTDWN is connected to VDD at power up, changing the state of this pin does not run classification.

Hi Carol,

Ok, thanks for the information. I am looking into what could be causing this issue and I will get feedback to you by end of day Friday.

Best,

Nate 

Carol,

Will you please send a picture of the top markings on the PSEs that aren't working properly? 

Thanks,

Nate

Sure!

Thanks, Carol.

Does every part you got from China have the same issue with SHTDWN pin? Can you share who the distributor of the chips is? 

Best Regards,

Nate 

We haven't started the assembly yet but I checked about 15 pieces from the spool and the problem is exactly the same. We bought these chips from a reseller and we don't know who the main distributor in China is. I can ask but I doubt they'll disclose it.

Ok, thank you for checking. Will you please ask them the name of distributor? 

Hi
I got below information:

"Hi sir.  We purchased  this 500pcs from a company named “SHENZHEN XINQIFA COMPANY”

They are not distributors or authorized companies, similar to OEM inventory supplier.

When the distributor is not in stock, we will consider this source, but we will check it carefully.

I am sure we checked whether the appearance of the chip is original, but we may have ignored its functions and parameters."

Hi Carol,

Unfortunately, we cannot support parts that are not purchased directly from TI or an authorized distributor. 

Best Regards,

Nate 

It's mean problem not exist for you???? I could buy the product from an authorized distributor but they don't have it, you don't supply them - is it my fault or yours?

Hi Carol,

We apologies for the supply issue. If you would like to get some devices from us for evaluation purposes to verify the issue, the TI website currently has TPS23861 in stock. I will contact you through email and if you can share your company info I can see if we have a sales representative that can work with you to supply parts. 

Best Regards,

Nate Inkster