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Original question:

TPS23881: About PCB Layout

TPS23881: Measure Power Consumption with TPS23881

Jesus Manuel Llaiqui Florez
Prodigy 40 points
Part Number: TPS23881
Other Parts Discussed in Thread: , MSP-EXP430FR5969, BOOST-PSEMTHR-007

Hello,

I'm a newcomer to this field, but I have a background in PCB design. I'm interested in using the TPS23881 to measure power consumption on a specific port and implement a feature to temporarily power down the port in case of any unusual behavior. Some PoE devices, like cameras, only require a brief power cycle to reset. Is this feasible with the TPS23881?

Thank you for your insights."

  • 0
    TI__Genius 14745 points

    Hi,

    Thank you for reaching out on E2E! 

    Yes, this is feasible with the TPS23881. If you are planning to use this port as a PoE port, you will use the Rsense circuit with the SenX/KsenseX pins in order to actively monitor your current. The voltage will be monitored through the Vpwr and DrainX pins.

    Registers 30h-3Fh will be your active power monitor report registers.

    There are a couple methods for resetting and will depend on your system design, however you may reset the actual device using the RESET pin or a Reset command to register 1Ah, or by OSS where you can individually shut down ports.

    Please note, depending on your operating mode, the port will shutdown when unusual behavior occurs, such as UVLO or overcurrent. You may also manually shutdown the port through register 19h.

    Regards,

    Brandon

  • 0 in reply to Brandon Beader
    Prodigy 40 points

    Thank you, Brandon, for your prompt response. Since the functionality I've proposed appears to be feasible, I'm interested in conducting functional tests using development modules. Specifically, I'm looking for a development board similar to the TPS23881EVM-008 but with fewer available ports. Ideally, it should be capable of supplying over 60W and be based on IEEE802.3bt technology, as my intention is to use it for monitoring PTZ cameras.

    Regards, 
    Jesus

  • 0 in reply to Jesus Manuel Llaiqui Florez
    TI__Genius 14745 points

    Hi Jesus,

    Unfortunately, the TPS23881EVM-008 + BOOST-PSEMTHR-007 combination is the lowest port count development module available for testing. This EVM is capable of supplying up to 90W on the 4-pair ports and is configurable using the downloadable GUI. In order to interface with the device, you would also need USB2ANY adapter. 

    Regards,

    Brandon

  • 0 in reply to Brandon Beader
    Prodigy 40 points

    Hello Brandon,

    Thank you very much for the quick responses. In case I am unable to purchase the mentioned modules:

    Can I create my own design utilizing the TPS23381, following the design guidelines and recommendations provided by the manufacturer?
    Is it possible to interface with the TPS23381 using a different microcontroller, or is it limited to microcontrollers from the same manufacturer? Given that it supports I2C communication, it seems like any microcontroller should be able to communicate with it easily, or does it require specific firmware for optimal operation?
    Best regards,
    Jesus Manuel

  • 0 in reply to Jesus Manuel Llaiqui Florez
    TI__Genius 14745 points

    Hi Jesus,

    Yes, you can create your own design using our design guidelines and should have no problems interfacing with any microcontroller from different vendors. My recommendation would obviously be to use same vendor so internal teams can communicate and help debug and troubleshoot faster, however that is purely a recommendation.

    Any MCU that supports I2C control will work to interface with TPS23881. Another recommendation would be to use MSP430 as we have created reference code for basic applications specific for PoE.

    This reference code includes different operating modes as well as loading SRAM upon bootup.

    Regards,

    Brandon

  • 0 in reply to Brandon Beader
    Prodigy 40 points

    Hi Brandon,

    Thank you very much for your prompt response; you've been incredibly helpful in clarifying my doubts. I'll now proceed with the PCB design and ensure that the pins are compatible with any microcontroller.

    - I'll definitely take your recommendation to use the MSP430 for initial testing.

    - Additionally, I'll be reaching out to you for guidance on the schematic and PCB design.

    - Could you please provide me with the links to the updated documents on PCB design and the current example schematics?

    Greetings,

    Jesus Manuel

  • 0 in reply to Jesus Manuel Llaiqui Florez
    TI__Genius 14745 points

    Hi Jesus,

    You can reach out to me and I will be able to assist in reviewing your schematic and PCB files!

    The latest PCB design guidelines can be found in the datasheet in all of our devices under layout guidelines. Example schematics, the best recomendation would be to reference the EVM's I have mentioned above. Please let me know if there is something specific I can help you locate or provide, thanks!

    Regards,

    Brandon Beader

  • 0 in reply to Brandon Beader
    Prodigy 40 points

    Hi Brandon,

    Thank you for your previous responses. I have a couple of quick questions:

    Can I utilize the MSP-EXP430FR5969 module to run the example code provided in the documentation?

    I noticed on page 126 of the TPS23881 datasheet, there's a section titled 'Connections on Unused Channels' which provides a connection diagram for scenarios where ports are not in use. Is it appropriate to use this diagram when I intend to use fewer ports?

    Your insights would be greatly appreciated.

    Regards,

    Jesus Manuel

  • 0 in reply to Jesus Manuel Llaiqui Florez
    TI__Genius 14745 points

    Hi Jesus,

    Yes, the MSP-EXP30FR5969 is the MSP430 launch pad which pairs with our BOOST-PSEMTHR-007 motherboard to testing demo App code.

    Yes, please reference that portion of the data sheet for unused pins, typically any sensing pins should be grounded when unused and gate driver pins should be left floating in order to not sink current when unused.

    Regards,

    Brandon

  • 0 in reply to Brandon Beader
    Prodigy 40 points

    Hi Brandon,

    Thank you for your assistance. I have a question regarding the BOOST-PSEMTHR-007 development board. Does the number of PCB layers affect its behavior? Specifically, if I intend to create a test board with only 2 ports, would it be feasible to use a two-layer PCB for this purpose?

    Your insights would be greatly appreciated.

    Best regards,
    Jesus

  • 0 in reply to Jesus Manuel Llaiqui Florez
    TI__Genius 14745 points

    Hi Jesus,

    It is feasible to do 2-layer design since there will not be many routing concerns. Only concern I would have would be ground shielding.

    Regards,

    Brandon