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TPS23881: Issue about the loading sram

Nan Zhang
Intellectual 1895 points
Part Number: TPS23881

Hi team,

       According to the application note(slave12E),after powering up the tps23881, we need to load sram for tps23881. And then send commends to set the registers from MCU via I2C.But the customers do not want to load sram using the MCU via I2C.

     

     So here are questions from customer,

    1. why we need to load the sram after powering up the tsp23881;

    2.can I skip such loading?(I find the answer saying it will not pass compliance test and ROM has some slight bugs. );

    3.according to the datasheet, the device has auto-mode. In my view, I could load the firmware to the tps23881. And  the device would work automatically after re-powering up without loading second time. Am I right?

    4.If the customers could not skip the loading sram, can customers add EEPROM with I2C interface where the tps23881 would load sram from EEPROM via I2C? How much is the software used for loading sram?

yours

nan

  • 0
    TI__Intellectual 1520 points

    Hello Nan, 

    1. The SRAM is loaded to ensure that the PSE device is interoperable with the latest POE enabled devices and can pass conformance test. 

    2. For the PSE to work properly, this step cannot be skipped. In order to comply with IEEE 802.3bt spec, the SRAM is necessary. 

    3. SRAM is a volatile form of memory, meaning that when the device loses power, the SRAM data will be lost. Due to the nature of SRAM, the SRAM will need to be loaded every time the device is powered back on.

    4. No, our PSE devices do not use EEPROM.

    Best Regards,

    Nate Inkster

  • 0 in reply to Nate Inkster
    TI__Intellectual 1895 points

    Hi Nate,

        Thanks for your reply.

         Here are the still some questions.

         1.If i have stable PSE and PD device(i use the poe only in my own system and do not use poe to power supply other commercial devices), does that means I do not have to load sram？

    Nate Inkster said:
    1. The SRAM is loaded to ensure that the PSE device is interoperable with the latest POE enabled devices and can pass conformance test. 

        2. is loading sram required by the IEEE 802.3bt standard? I could not find in IEEE 802.bt standard.

    Nate Inkster said:
    2. For the PSE to work properly, this step cannot be skipped. In order to comply with IEEE 802.3bt spec, the SRAM is necessary. 

    YOURS

    NAN

  • 0 in reply to Nan Zhang
    TI__Genius 15275 points

    Hi Nan,

    I would still recommend loading SRAM as the SRAM is used to also patch any bugs found in the ROM. 

    SRAM is not required by IEEE802.3bt, however in order to stay IEEE802.3bt compliant, you will need to load SRAM.

    Regards,

    Brandon