Multiple Step-Down Voltage Rails from a single DC Power Supply












1














I have one working PCB which has three different Voltage Rails: 3.3V, 4V and 1.8V. They are generated using three separate step-down buck converters. The input voltage to all the converters is a single DC Power Supply (12V).




  • Buck Converter Generating 4V powers 4G LTE Module (Load 2.5A)

  • Buck Converter generating 1.8V powers LoRa IC SX1301 (Load 1A)

  • Buck Converter generating 3.3V powers iMX6ULL System-on-module (Load: 3A)


enter image description here



These three different buck converters are occupying alot of PCB space and increasing the BOM. I am thinking to implement single IC solution for my system. A quick google search landed me on two solutions.




  • A Triple Step-Down Converter from TI (TPS6526x)

  • Using a single Buck Converter to generate multiple voltages. (The link is over here).


What should I consider? Is there any different solution other than listed above?



EDIT:
The LoRaWAN IC is SX1301 and it requires 1.8V power supply.










share|improve this question
























  • Can’t you use the same 3.3V supply for at least the SX1231 and iMX6ULL? (maybe also the unnamed LTE modem)
    – Michael
    2 days ago












  • Sorry. The IC is SX1301.
    – abhiarora
    2 days ago






  • 1




    The single point option for all three power supply using TI webbench works, as long as you use all the components mentioned in their BOM..only problem I find is if the IC fails, all three power lines will go for a toss as also pointed out in one of the answers. Do look deeply for Reliabilty of IC, along with operating temperatures when you go for full load.
    – AKR
    2 days ago
















1














I have one working PCB which has three different Voltage Rails: 3.3V, 4V and 1.8V. They are generated using three separate step-down buck converters. The input voltage to all the converters is a single DC Power Supply (12V).




  • Buck Converter Generating 4V powers 4G LTE Module (Load 2.5A)

  • Buck Converter generating 1.8V powers LoRa IC SX1301 (Load 1A)

  • Buck Converter generating 3.3V powers iMX6ULL System-on-module (Load: 3A)


enter image description here



These three different buck converters are occupying alot of PCB space and increasing the BOM. I am thinking to implement single IC solution for my system. A quick google search landed me on two solutions.




  • A Triple Step-Down Converter from TI (TPS6526x)

  • Using a single Buck Converter to generate multiple voltages. (The link is over here).


What should I consider? Is there any different solution other than listed above?



EDIT:
The LoRaWAN IC is SX1301 and it requires 1.8V power supply.










share|improve this question
























  • Can’t you use the same 3.3V supply for at least the SX1231 and iMX6ULL? (maybe also the unnamed LTE modem)
    – Michael
    2 days ago












  • Sorry. The IC is SX1301.
    – abhiarora
    2 days ago






  • 1




    The single point option for all three power supply using TI webbench works, as long as you use all the components mentioned in their BOM..only problem I find is if the IC fails, all three power lines will go for a toss as also pointed out in one of the answers. Do look deeply for Reliabilty of IC, along with operating temperatures when you go for full load.
    – AKR
    2 days ago














1












1








1







I have one working PCB which has three different Voltage Rails: 3.3V, 4V and 1.8V. They are generated using three separate step-down buck converters. The input voltage to all the converters is a single DC Power Supply (12V).




  • Buck Converter Generating 4V powers 4G LTE Module (Load 2.5A)

  • Buck Converter generating 1.8V powers LoRa IC SX1301 (Load 1A)

  • Buck Converter generating 3.3V powers iMX6ULL System-on-module (Load: 3A)


enter image description here



These three different buck converters are occupying alot of PCB space and increasing the BOM. I am thinking to implement single IC solution for my system. A quick google search landed me on two solutions.




  • A Triple Step-Down Converter from TI (TPS6526x)

  • Using a single Buck Converter to generate multiple voltages. (The link is over here).


What should I consider? Is there any different solution other than listed above?



EDIT:
The LoRaWAN IC is SX1301 and it requires 1.8V power supply.










share|improve this question















I have one working PCB which has three different Voltage Rails: 3.3V, 4V and 1.8V. They are generated using three separate step-down buck converters. The input voltage to all the converters is a single DC Power Supply (12V).




  • Buck Converter Generating 4V powers 4G LTE Module (Load 2.5A)

  • Buck Converter generating 1.8V powers LoRa IC SX1301 (Load 1A)

  • Buck Converter generating 3.3V powers iMX6ULL System-on-module (Load: 3A)


enter image description here



These three different buck converters are occupying alot of PCB space and increasing the BOM. I am thinking to implement single IC solution for my system. A quick google search landed me on two solutions.




  • A Triple Step-Down Converter from TI (TPS6526x)

  • Using a single Buck Converter to generate multiple voltages. (The link is over here).


What should I consider? Is there any different solution other than listed above?



EDIT:
The LoRaWAN IC is SX1301 and it requires 1.8V power supply.







power-supply voltage-regulator circuit-design switch-mode-power-supply buck






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 2 days ago









StainlessSteelRat

3,196617




3,196617










asked Dec 29 '18 at 17:51









abhiarora

440416




440416












  • Can’t you use the same 3.3V supply for at least the SX1231 and iMX6ULL? (maybe also the unnamed LTE modem)
    – Michael
    2 days ago












  • Sorry. The IC is SX1301.
    – abhiarora
    2 days ago






  • 1




    The single point option for all three power supply using TI webbench works, as long as you use all the components mentioned in their BOM..only problem I find is if the IC fails, all three power lines will go for a toss as also pointed out in one of the answers. Do look deeply for Reliabilty of IC, along with operating temperatures when you go for full load.
    – AKR
    2 days ago


















  • Can’t you use the same 3.3V supply for at least the SX1231 and iMX6ULL? (maybe also the unnamed LTE modem)
    – Michael
    2 days ago












  • Sorry. The IC is SX1301.
    – abhiarora
    2 days ago






  • 1




    The single point option for all three power supply using TI webbench works, as long as you use all the components mentioned in their BOM..only problem I find is if the IC fails, all three power lines will go for a toss as also pointed out in one of the answers. Do look deeply for Reliabilty of IC, along with operating temperatures when you go for full load.
    – AKR
    2 days ago
















Can’t you use the same 3.3V supply for at least the SX1231 and iMX6ULL? (maybe also the unnamed LTE modem)
– Michael
2 days ago






Can’t you use the same 3.3V supply for at least the SX1231 and iMX6ULL? (maybe also the unnamed LTE modem)
– Michael
2 days ago














Sorry. The IC is SX1301.
– abhiarora
2 days ago




Sorry. The IC is SX1301.
– abhiarora
2 days ago




1




1




The single point option for all three power supply using TI webbench works, as long as you use all the components mentioned in their BOM..only problem I find is if the IC fails, all three power lines will go for a toss as also pointed out in one of the answers. Do look deeply for Reliabilty of IC, along with operating temperatures when you go for full load.
– AKR
2 days ago




The single point option for all three power supply using TI webbench works, as long as you use all the components mentioned in their BOM..only problem I find is if the IC fails, all three power lines will go for a toss as also pointed out in one of the answers. Do look deeply for Reliabilty of IC, along with operating temperatures when you go for full load.
– AKR
2 days ago










2 Answers
2






active

oldest

votes


















2














The triple converter gets you some space savings while maintaining the basic simplicity of buck regulators. However, the chip now is a single point of failure. Multiple outputs from one switching stage will save more space. However, the magnetics no longer are simple inductors so the added design and development time might eat up or exceed the BOM savings. Unless you're talking about high volume, I'd go with a triple controller. I prefer Linear Tech, but TI should be fine.






share|improve this answer





















  • Where to start for magnetics of single switching stage?
    – abhiarora
    2 days ago






  • 2




    Triple converters also often have startup/shutdown features that make it easier to keep power sequencing constraints like "the 5V rail may not drop more than 0.3V below the 3.3V rail at any time".
    – Simon Richter
    2 days ago



















2














There are many triple output SMPS on the market and in Design Reference sites like Analog, LTI, TI but they tend not to be give out the larger power designs that are worth more and may have OEM IT property tricks or custom magnetics.



You need to assess your cost, performance, skills, time and qty tradeoffs then consider everything including AC to DC, EMI, performance, cost and reliability.



If you have the skills then you will have at least a 1 page list of all specs.



If you do then expand it to at least 5 pages and do some due diligence cost analysis and see if you can achieve $5 in volume for 22W from AC to triple output DC like this possibility.
enter image description here






share|improve this answer





















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    2 Answers
    2






    active

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    2 Answers
    2






    active

    oldest

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    active

    oldest

    votes






    active

    oldest

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    2














    The triple converter gets you some space savings while maintaining the basic simplicity of buck regulators. However, the chip now is a single point of failure. Multiple outputs from one switching stage will save more space. However, the magnetics no longer are simple inductors so the added design and development time might eat up or exceed the BOM savings. Unless you're talking about high volume, I'd go with a triple controller. I prefer Linear Tech, but TI should be fine.






    share|improve this answer





















    • Where to start for magnetics of single switching stage?
      – abhiarora
      2 days ago






    • 2




      Triple converters also often have startup/shutdown features that make it easier to keep power sequencing constraints like "the 5V rail may not drop more than 0.3V below the 3.3V rail at any time".
      – Simon Richter
      2 days ago
















    2














    The triple converter gets you some space savings while maintaining the basic simplicity of buck regulators. However, the chip now is a single point of failure. Multiple outputs from one switching stage will save more space. However, the magnetics no longer are simple inductors so the added design and development time might eat up or exceed the BOM savings. Unless you're talking about high volume, I'd go with a triple controller. I prefer Linear Tech, but TI should be fine.






    share|improve this answer





















    • Where to start for magnetics of single switching stage?
      – abhiarora
      2 days ago






    • 2




      Triple converters also often have startup/shutdown features that make it easier to keep power sequencing constraints like "the 5V rail may not drop more than 0.3V below the 3.3V rail at any time".
      – Simon Richter
      2 days ago














    2












    2








    2






    The triple converter gets you some space savings while maintaining the basic simplicity of buck regulators. However, the chip now is a single point of failure. Multiple outputs from one switching stage will save more space. However, the magnetics no longer are simple inductors so the added design and development time might eat up or exceed the BOM savings. Unless you're talking about high volume, I'd go with a triple controller. I prefer Linear Tech, but TI should be fine.






    share|improve this answer












    The triple converter gets you some space savings while maintaining the basic simplicity of buck regulators. However, the chip now is a single point of failure. Multiple outputs from one switching stage will save more space. However, the magnetics no longer are simple inductors so the added design and development time might eat up or exceed the BOM savings. Unless you're talking about high volume, I'd go with a triple controller. I prefer Linear Tech, but TI should be fine.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 2 days ago









    AnalogKid

    1,49325




    1,49325












    • Where to start for magnetics of single switching stage?
      – abhiarora
      2 days ago






    • 2




      Triple converters also often have startup/shutdown features that make it easier to keep power sequencing constraints like "the 5V rail may not drop more than 0.3V below the 3.3V rail at any time".
      – Simon Richter
      2 days ago


















    • Where to start for magnetics of single switching stage?
      – abhiarora
      2 days ago






    • 2




      Triple converters also often have startup/shutdown features that make it easier to keep power sequencing constraints like "the 5V rail may not drop more than 0.3V below the 3.3V rail at any time".
      – Simon Richter
      2 days ago
















    Where to start for magnetics of single switching stage?
    – abhiarora
    2 days ago




    Where to start for magnetics of single switching stage?
    – abhiarora
    2 days ago




    2




    2




    Triple converters also often have startup/shutdown features that make it easier to keep power sequencing constraints like "the 5V rail may not drop more than 0.3V below the 3.3V rail at any time".
    – Simon Richter
    2 days ago




    Triple converters also often have startup/shutdown features that make it easier to keep power sequencing constraints like "the 5V rail may not drop more than 0.3V below the 3.3V rail at any time".
    – Simon Richter
    2 days ago













    2














    There are many triple output SMPS on the market and in Design Reference sites like Analog, LTI, TI but they tend not to be give out the larger power designs that are worth more and may have OEM IT property tricks or custom magnetics.



    You need to assess your cost, performance, skills, time and qty tradeoffs then consider everything including AC to DC, EMI, performance, cost and reliability.



    If you have the skills then you will have at least a 1 page list of all specs.



    If you do then expand it to at least 5 pages and do some due diligence cost analysis and see if you can achieve $5 in volume for 22W from AC to triple output DC like this possibility.
    enter image description here






    share|improve this answer


























      2














      There are many triple output SMPS on the market and in Design Reference sites like Analog, LTI, TI but they tend not to be give out the larger power designs that are worth more and may have OEM IT property tricks or custom magnetics.



      You need to assess your cost, performance, skills, time and qty tradeoffs then consider everything including AC to DC, EMI, performance, cost and reliability.



      If you have the skills then you will have at least a 1 page list of all specs.



      If you do then expand it to at least 5 pages and do some due diligence cost analysis and see if you can achieve $5 in volume for 22W from AC to triple output DC like this possibility.
      enter image description here






      share|improve this answer
























        2












        2








        2






        There are many triple output SMPS on the market and in Design Reference sites like Analog, LTI, TI but they tend not to be give out the larger power designs that are worth more and may have OEM IT property tricks or custom magnetics.



        You need to assess your cost, performance, skills, time and qty tradeoffs then consider everything including AC to DC, EMI, performance, cost and reliability.



        If you have the skills then you will have at least a 1 page list of all specs.



        If you do then expand it to at least 5 pages and do some due diligence cost analysis and see if you can achieve $5 in volume for 22W from AC to triple output DC like this possibility.
        enter image description here






        share|improve this answer












        There are many triple output SMPS on the market and in Design Reference sites like Analog, LTI, TI but they tend not to be give out the larger power designs that are worth more and may have OEM IT property tricks or custom magnetics.



        You need to assess your cost, performance, skills, time and qty tradeoffs then consider everything including AC to DC, EMI, performance, cost and reliability.



        If you have the skills then you will have at least a 1 page list of all specs.



        If you do then expand it to at least 5 pages and do some due diligence cost analysis and see if you can achieve $5 in volume for 22W from AC to triple output DC like this possibility.
        enter image description here







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 2 days ago









        Tony EE rocketscientist

        62.1k22193




        62.1k22193






























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