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SN6505A: The SN6505x is a low-noise, low-EMI push-pull transformer driver,

Navi Singh
Prodigy 230 points
Part Number: SN6505A
Other Parts Discussed in Thread: PMP4190, , , SN6505B, TINA-TI

I have design Low wattage SMPS using of SN6505A and PMP4190.

Input-5V(3 to 6)

Output- 5V/400mA

Isolation-1500VDC

Please share me reference Design as above part number.

My Mail-vpsingh1020@gmail.com

  • 0
    TI__Guru 54245 points

    Hi Navi,

    Thank you for reaching out.

    For reference schematic, please refer to the SN6505AEVM. I am sharing a link to the EVM folder on TI website. This EVM supports 5V output with >400mA output current and an isolation withstand voltage (VISO) of 5000VRMS.

    https://www.ti.com/tool/SN6505AEVM

    If you meant to require 1500VDC working voltage (VIOWM) and not isolation withstand voltage then you may have to reach out to the transformer vendor of your choice with your request. They maybe able to provide you with this information and if they support it. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 230 points

    Hi Sir,

    I am starting schematics as per SN6505B EVM boards with Wurth Transformer 750315371. I have take load 5V/400mA between I/P Voltage 3 to 6  and Nominal Voltage 5VDC.

    I have some doubt-

    1. Without LDO (TPS7670100 )I have take load Transformer.

    2. Why use LDO

    3 Can I design without LDO

  • 0 in reply to Koteshwar Rao
    Prodigy 230 points

    Hi Sir,

    I am starting schematics as per SN6505B EVM boards with Wurth Transformer 750315371. I have take load 5V/400mA between I/P Voltage 3 to 6  and Nominal Voltage 5VDC.

    I have some doubt-

    1. Without LDO (TPS7670100 )I have take load Transformer.

    2. Why use LDO

    3 Can I design without LDO

  • 0 in reply to Koteshwar Rao
    Prodigy 230 points

    Can you share you  Contact Number and Email ID

  • 0 in reply to Navi Singh
    TI__Guru 54245 points

    Hi Navi,

    Glad to know that you are going to start your schematic with SN6505B and 750315371 transformer. Please note that the device SN6505B recommended input operating voltage is 2.25V to 5.5V, we do not recommend operating the device with voltage >5.5V.

    Navi Singh said:
    1. Without LDO (TPS7670100 )I have take load Transformer.

    Sorry, I didn't completely understand your question. Please help elaborate your question.

    Navi Singh said:
    2. Why use LDO

    SN6505 is an open-loop push-pull transformer driver without any output feedback and not a closed loop power supply regulator. Hence, the SN6505 based solution will have isolated but unregulated output where any variation input will reflect at the output directly. If the input is well regulated, then the output will also be similar and an LDO might not be needed. But if your input is not regulated, then you might have to use an appropriate LDO at the output of SN6505 to get a regulated output. I hope this clarifies why an LDO maybe needed based on the application requirements.

    Navi Singh said:
    3 Can I design without LDO

    I believe my previous point addresses this question as well.

    Navi Singh said:
    Can you share you  Contact Number and Email ID

    The E2E forum is the best place to get fast answers to your questions. Many of your questions might already be answered on the forum, so we first recommend searching on E2E to check for your questions and you might have answers already readily available. If you don't find search results answering your questions, please feel free to post a new question and will respond within 24 hours of your question. This is the fastest way to get TI customer support. Let me know if you have any further questions, thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 230 points

    Thanks Sir,

    I have got your point.

    Point 1 (LDO is not used): Input Voltage is not change Output Voltage is always fixed. If input voltage is variation than Output voltage is same variation.

    If load is variation than Output is also fixed.

    Point 2(LDO Used)- input voltage is variation or Fixed, Output voltage is Constant .

  • +1 in reply to Navi Singh
    TI__Guru 54245 points

    Hi Navi,

    Thanks for following up.

    Navi Singh said:
    Point 1 (LDO is not used): Input Voltage is not change Output Voltage is always fixed. If input voltage is variation than Output voltage is same variation.

    Your understanding is correct.

    Navi Singh said:
    If load is variation than Output is also fixed.

    A increase in load increases conduction losses hence, the actual output voltage will drop slightly accordingly. Please refer to the output voltage vs output current graphs provided in the datasheet for getting an idea how the variation looks like. I am copying below the output voltage vs output current graph from datasheet for the solution with transformer 750315371.

    Navi Singh said:
    Point 2(LDO Used)- input voltage is variation or Fixed, Output voltage is Constant .

    Your understanding is correct. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 230 points

    Above Case I have design transformer-

    Input No of Turn Wire - 05

    Output No of Turn Wire- 05 

    Wire Size- 0.5mm

    This is correct.

    In My second Solutions give me suggestion-

    Hi,

    I have design SMPS using of PMP4190.

    I/P-3 VDC to 6VDC

    O/P-5V/400mA with 1500VDC isolation

    I am structing Transformer. As per reference design I am not found transformer.

    So Please me suggest alternate part number of transformer...

    Read more.

  • 0 in reply to Navi Singh
    TI__Guru 54245 points

    Hi Navi,

    Thanks for further inputs.

    Regarding your second question, I see that you posted this question on simulation forum. The team should get back to you with suggestions. The transformer that you see in PMP4190 should also work for your requirement as the solution in PMP4190 meets your specifications. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 230 points

    I have taken simulator board SM6505B in TI Web. I will check simulator SN6505B using of tina software.

    Why are show 139V Vout:7 and between Iload:8 andLoad 12.5 .

    That is output voltage?

  • 0 in reply to Navi Singh
    TI__Guru 54245 points

    Hi Navi,

    Thanks for trying to simulate the device SN6505B in TINA-TI.

    Please note that the values 139 in 9.18E-139V is a negative exponent which means 9.18*10^-139V. This is basically same as 0V but the tool is trying to report the exact value even if it is very small and can technically be considered 0V.

    Please run AC Transient Analysis to see the waveform and device operation.

    I would also recommend that you create a new E2E post with appropriate title for every new question so that it helps others who have similar questions and search E2E forum for answers. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 230 points

    OK

    After next I will post new question.

    Where are measurement output voltage .

  • 0 in reply to Navi Singh
    TI__Guru 54245 points

    Hi Navi,

    You can use test points at different nodes of schematic and those will show up as outputs. For example, the test point at output labeled as VOUT:7 is one of such nodes will show up in your AC transient analysis.

    You can also go through video tutorials for TINA on TI website. I am copy below the introduction link but you can search for TINA to see all the videos associated with TINA-TI tool. Thanks.

    https://www.ti.com/video/4541013794001?keyMatch=TINA


    Regards,
    Koteshwar Rao