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SN6505A-Q1: SN6505A-Q1 Hardware review

Manjunath G14
Expert 2075 points
Part Number: SN6505A-Q1
Other Parts Discussed in Thread: SN6505A, ISO1042

Hello TI Team,

Please review the attached SN6505A circuit.

Design Contains 3.3V to 5V Isolated circuit and Ioslated CAN Transciever.

Please review both ASAP

Konnect-4G_Outjob.PDF

  • 0
    TI__Genius 17100 points

    Hi Manjunath,

    Thank you for posting to E2E!

    The SN6505A circuit of the schematic looks great; we will just recommend R65 be replaced with a 4.7kΩ resistor if possible and that in the PCB layout, C88 be placed within 2mm of the transformer's primary-side center tap. As a note, the LDO used here has a 150mA recommended current capability and there is a label near the output stating "5V/0.5A." If higher current is needed at the output, this LDO should be replaced.

    The ISO1042 sub-circuit also looks good as well. Termination values and decoupling are okay.


    Please let us know if you ave additional questions or follow-up comments.


    Have a great weekend!
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    Expert 2075 points

    Hi Manuel,

    Thanks for the quick response and for the review comments.

    For the current Power isolated circuit, I used "750316032", AS per the spec of this transformer Which can take 3.3V and gives 5V at his secondary Side.

    Then same 5V is given to "TPS76350QDBVRQ1" LDO which is used for voltage stabilization which again takes 5V and gives right? The LDO has a 300mV dropout voltage here.

    So can you please explain on LDO is used here.

    Thanks

  • 0 in reply to Manjunath G14
    Expert 2075 points

    and also If you can suggest low cost LDO which gives 500mA it is greatful.

  • 0 in reply to Manjunath G14
    TI__Genius 17100 points

    Hi Manjunath,

    You're welcome! 750316032 has a turns ratio of N = 1:2, which is high enough to transfer 3.3V across the isolation above 5V (~6.3V at 500mA,) specifically for use with LDOs on the output power supply. Without an LDO, the output power supply could vary widely as load current changes.

    The LDO in this schematic, TPS76350-Q1, is an acceptable LDO, and although we do not provide quotes for customers on E2E, our 1ku price on TI.com for uA78M05-Q1 is among the lowest for LDO's that meet operating specs in this schematic.

    Please let me know your thoughts and comments.


    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    Expert 2075 points

    Hi Manuel,

    Understand.

    Please find attached updated schematic and review the same ASAP. 

    6116.Konnect-4G_Outjob.PDF

  • 0 in reply to Manjunath G14
    TI__Genius 17100 points

    HI Manjunath,

    This schematic looks great! If the application is for automotive use cases, UA78M05QDCY (-Q1 automotive version) is available.

    Other than that, no changes are necessary.


    Respectfully,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    Expert 2075 points

    Hi Manuel,

    Thanks for the review comments.