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LM5185: Two output power supply using LM5185

ADITYA MENE
Prodigy 60 points
Part Number: LM5185
Other Parts Discussed in Thread: LM5180, LM25184

Tool/software:

Hi Sir

        I want to design a power supply using LM5185 IC which will have two outputs. Will you please suggest suitable transformer for this application. Please look into this

IC: LM5185

Input Voltage (min) 10 Volts

Input Voltage (nominal) 24 Volts

Output 1:  5 Volts 1 A DC

Output 2: 5 Volts 200 mA DC

Isolation: Yes

Operating Temperature: - 40 °C to + 85 °C

Thanks & Regards

  • 0
    TI__Expert 5490 points

    Hi Aditya,

    The responsible engineer is out of office this week and will be back next week.

    Thanks,

    Nitya

  • 0 in reply to Nityanand Hegde
    TI__Guru* 78540 points

    Hi Aditya,

    Thank you for designing with the LM5185.  Could you tell if the two 5V-output rails are isolated from each other or not?  I need to see if an off-the-shelf transformer exists for your application.

    Thanks,

    Youhao

  • 0 in reply to Youhao Xi
    Prodigy 60 points

    Hi Youhao

    Thank you for your valuable response. We are looking for 5V-output rails are isolated from each other for this application.

    Thanks & Regards

    Aditya 

  • +1 in reply to ADITYA MENE
    TI__Guru* 78540 points

    Hi Aditya,

    I am afraid you may need to get a custom designed transformer.  I cannot find a suitable off-the-shelf transformer. Can you contact your preferred magnetics vendor or vendors?

    Thanks,

    Youhao

  • 0 in reply to Youhao Xi
    Prodigy 60 points

    Hi Youhao 

    Thanks you for your valuable response. Can you suggest any transformer for  5V-output rails are non-isolated from each other for this application.

  • +1 in reply to ADITYA MENE
    TI__Guru* 78540 points

    Hi Aditya, 

    When I replied to you previously, I was thinking of YA8779-BL from Coilcraft for it has two secondary windings for 5V, but it may not meet isolation required.  See below

    It seems windings 5-7 and 6-8 can be used to produce two separate 5V rails but they may not meet the isolation requirement due to the pin out arrangement.  

    Unfortunately, Coilcraft told me after my inquiry a couple of days ago that this is not a safe approach, because the two secondary windings were supposed to be used in parallel, so there may be solder bridge between Pins 7 and 8, and 5 and 6.  However, they are willing to modify the pin out and have the two secondary windings isolated from each other.  If this is an approach, you may contact them at cust_service@coilcraft.com.

    Hope this helps.

    Best Regards,

    Youhao

  • 0 in reply to Youhao Xi
    Prodigy 60 points

    Hi Youhao,

    Thanks buddy for your valuable guidance means a lot. But I have one more concern can we use this transformer (YA8779) with LM5180 IC as in this case we won't be using external MOSFET for switching and once again thanks a lot.

    Thanks & Regards

    Aditya Mene

  • 0 in reply to ADITYA MENE
    TI__Guru* 78540 points

    Hi Aditya,

    LM5180's 1.5A current limit will prevent you from supporting your full load.  The LM25184 can work but the max input voltage is limited to 42V. 

    Please use our design calculators.

    Regards,

    Youhao