Ferrite vs iron powder toroid for buck converter?












2














I'm wondering about the difference between small (13mm outer dia) ferrite and the yellow white iron powder toroids. Will the ferrite toroids saturate at 5A current? I'm planning on using the cores for buck converters (mostly 3A at probably below 200KHz). (Sorry for naive questions, I don't know much about inductors.)



These are the ones I am looking at:



Ferrite: https://www.ebay.com/itm/Metal-Core-Power-Inductor-Ferrite-Rings-Toroid-Cord-25x10x15mm/310980203521 (also available in 13mm outer dia)



Iron powder: https://www.ebay.com/itm/7mm-Inner-Diameter-Ferrite-Ring-Iron-Toroid-Cores-Yellow-White-50PCS-LW/181834403242



Most of the buck converters seem to use the yellow white iron powder toroids like this https://www.ebay.com/itm/5Pcs-Toroid-Core-Inductors-Wire-Wind-Wound-mah-100uH-6A-Coil-DIY/221981982278 .



From searching on the internet, the yellow white toroids seem to have a permeability of 75, and the ferrite has a permeability of 2300 or so. Is this important for saturation. I have some toroids and an LCR meter, and the ferrite toroid needs only a few turns of wire to get a 1mH inductor, vs many more turns for the iron powder core. Will this matter if peak current through the inductor is limited?



I'm guessing the ferrite toroids are great at low currents (0-100mA) and low frequencies (<100KHz, as I can get more inductance with fewer turns). But, are they also good for higher currents (like 5-6A peak)?



Any help will be appreciated.



[PS: also another reason I ask, is that at my place, the ferrite cores are half the price of the iron powder cores.]










share|improve this question
























  • I was trying to figure this out not long ago. I ended up going with the iron powder power inductor cores(yellow and white), but I've learned they have a functional limit of ~1Mhz due to pole switching losses or some such, so I've been wondering what kind of inductor is used in higher frequency power converters.
    – K H
    49 mins ago


















2














I'm wondering about the difference between small (13mm outer dia) ferrite and the yellow white iron powder toroids. Will the ferrite toroids saturate at 5A current? I'm planning on using the cores for buck converters (mostly 3A at probably below 200KHz). (Sorry for naive questions, I don't know much about inductors.)



These are the ones I am looking at:



Ferrite: https://www.ebay.com/itm/Metal-Core-Power-Inductor-Ferrite-Rings-Toroid-Cord-25x10x15mm/310980203521 (also available in 13mm outer dia)



Iron powder: https://www.ebay.com/itm/7mm-Inner-Diameter-Ferrite-Ring-Iron-Toroid-Cores-Yellow-White-50PCS-LW/181834403242



Most of the buck converters seem to use the yellow white iron powder toroids like this https://www.ebay.com/itm/5Pcs-Toroid-Core-Inductors-Wire-Wind-Wound-mah-100uH-6A-Coil-DIY/221981982278 .



From searching on the internet, the yellow white toroids seem to have a permeability of 75, and the ferrite has a permeability of 2300 or so. Is this important for saturation. I have some toroids and an LCR meter, and the ferrite toroid needs only a few turns of wire to get a 1mH inductor, vs many more turns for the iron powder core. Will this matter if peak current through the inductor is limited?



I'm guessing the ferrite toroids are great at low currents (0-100mA) and low frequencies (<100KHz, as I can get more inductance with fewer turns). But, are they also good for higher currents (like 5-6A peak)?



Any help will be appreciated.



[PS: also another reason I ask, is that at my place, the ferrite cores are half the price of the iron powder cores.]










share|improve this question
























  • I was trying to figure this out not long ago. I ended up going with the iron powder power inductor cores(yellow and white), but I've learned they have a functional limit of ~1Mhz due to pole switching losses or some such, so I've been wondering what kind of inductor is used in higher frequency power converters.
    – K H
    49 mins ago
















2












2








2


0





I'm wondering about the difference between small (13mm outer dia) ferrite and the yellow white iron powder toroids. Will the ferrite toroids saturate at 5A current? I'm planning on using the cores for buck converters (mostly 3A at probably below 200KHz). (Sorry for naive questions, I don't know much about inductors.)



These are the ones I am looking at:



Ferrite: https://www.ebay.com/itm/Metal-Core-Power-Inductor-Ferrite-Rings-Toroid-Cord-25x10x15mm/310980203521 (also available in 13mm outer dia)



Iron powder: https://www.ebay.com/itm/7mm-Inner-Diameter-Ferrite-Ring-Iron-Toroid-Cores-Yellow-White-50PCS-LW/181834403242



Most of the buck converters seem to use the yellow white iron powder toroids like this https://www.ebay.com/itm/5Pcs-Toroid-Core-Inductors-Wire-Wind-Wound-mah-100uH-6A-Coil-DIY/221981982278 .



From searching on the internet, the yellow white toroids seem to have a permeability of 75, and the ferrite has a permeability of 2300 or so. Is this important for saturation. I have some toroids and an LCR meter, and the ferrite toroid needs only a few turns of wire to get a 1mH inductor, vs many more turns for the iron powder core. Will this matter if peak current through the inductor is limited?



I'm guessing the ferrite toroids are great at low currents (0-100mA) and low frequencies (<100KHz, as I can get more inductance with fewer turns). But, are they also good for higher currents (like 5-6A peak)?



Any help will be appreciated.



[PS: also another reason I ask, is that at my place, the ferrite cores are half the price of the iron powder cores.]










share|improve this question















I'm wondering about the difference between small (13mm outer dia) ferrite and the yellow white iron powder toroids. Will the ferrite toroids saturate at 5A current? I'm planning on using the cores for buck converters (mostly 3A at probably below 200KHz). (Sorry for naive questions, I don't know much about inductors.)



These are the ones I am looking at:



Ferrite: https://www.ebay.com/itm/Metal-Core-Power-Inductor-Ferrite-Rings-Toroid-Cord-25x10x15mm/310980203521 (also available in 13mm outer dia)



Iron powder: https://www.ebay.com/itm/7mm-Inner-Diameter-Ferrite-Ring-Iron-Toroid-Cores-Yellow-White-50PCS-LW/181834403242



Most of the buck converters seem to use the yellow white iron powder toroids like this https://www.ebay.com/itm/5Pcs-Toroid-Core-Inductors-Wire-Wind-Wound-mah-100uH-6A-Coil-DIY/221981982278 .



From searching on the internet, the yellow white toroids seem to have a permeability of 75, and the ferrite has a permeability of 2300 or so. Is this important for saturation. I have some toroids and an LCR meter, and the ferrite toroid needs only a few turns of wire to get a 1mH inductor, vs many more turns for the iron powder core. Will this matter if peak current through the inductor is limited?



I'm guessing the ferrite toroids are great at low currents (0-100mA) and low frequencies (<100KHz, as I can get more inductance with fewer turns). But, are they also good for higher currents (like 5-6A peak)?



Any help will be appreciated.



[PS: also another reason I ask, is that at my place, the ferrite cores are half the price of the iron powder cores.]







inductor ferrite iron toroid






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 51 mins ago







Indraneel

















asked 58 mins ago









IndraneelIndraneel

1,087411




1,087411












  • I was trying to figure this out not long ago. I ended up going with the iron powder power inductor cores(yellow and white), but I've learned they have a functional limit of ~1Mhz due to pole switching losses or some such, so I've been wondering what kind of inductor is used in higher frequency power converters.
    – K H
    49 mins ago




















  • I was trying to figure this out not long ago. I ended up going with the iron powder power inductor cores(yellow and white), but I've learned they have a functional limit of ~1Mhz due to pole switching losses or some such, so I've been wondering what kind of inductor is used in higher frequency power converters.
    – K H
    49 mins ago


















I was trying to figure this out not long ago. I ended up going with the iron powder power inductor cores(yellow and white), but I've learned they have a functional limit of ~1Mhz due to pole switching losses or some such, so I've been wondering what kind of inductor is used in higher frequency power converters.
– K H
49 mins ago






I was trying to figure this out not long ago. I ended up going with the iron powder power inductor cores(yellow and white), but I've learned they have a functional limit of ~1Mhz due to pole switching losses or some such, so I've been wondering what kind of inductor is used in higher frequency power converters.
– K H
49 mins ago












2 Answers
2






active

oldest

votes


















3














There is a color standard for painted toroids, and yellow means it has hysteresis to prevent saturation and is meant for filter inductors. But a side effect is that it has very low permeability. Black ferrite is usually a good choice for transformers. Blue is an expensive Permalloy that is more efficient than ferrite. Green is low frequency filters made with silicon steel tape wrapped to form a toroid.



This chart is generic as it is not including fine details such as permeability, and does not state if iron, steel, ferrite or permalloy, which is a nickel-iron alloy.



PC power supplies can put out over 1,000 watts and they use E cores as they are easy to wind by machine, and can have a cross section large enough to handle as much as 10 ampere/turns, and a tiny 10 mil air gap helps a lot. Large toroids need expensive winding machine heads so toroids are better used at low voltages were the number of windings is low, such as car stereo power supplies.



NOTE: Sometimes practical reasons determine what material and shape of transformer are used, which is not always the best choice. Cost and size compete with efficiency. The opinions of engineering and marketing and sales are not the same, and who wins determines what is used. "Just good enough" wins most of the time.



enter image description here






share|improve this answer























  • And what about the unpainted black ferrites? That's the cheapest one at my place. One can also see them inside CFL lamps. I already know they work at low currents very well with a MC34063, and also as jewel thief. But how about 3A buck converter with LM2596?
    – Indraneel
    46 mins ago












  • For a given design based on a PWM IC the manufacture often specifies core material or a part number that you can search with. There a many toroid manufactures all over the world.
    – Sparky256
    37 mins ago










  • Well, the LM2596 datasheet says ferrite E core or ferrite bobbin or powdered iron toroid. So, is this because the peak current is already too high for ferrite cores without an air gap?
    – Indraneel
    28 mins ago










  • I added some more to my answer.
    – Sparky256
    3 mins ago



















1














Powdered Iron is Cheap and more forgiving when it comes to saturation due to the more gradual BH curves .There is a down side when for Buck and most other DC/DC convertors .The inductor ripple current will cause more core losses in the powdered iron than in most ferrites .It is quite normal to have AC ripple currents at about 33% of the max DC load current .So on an orthodox hardswitched peak current mode switching regime which most easy to buy chips are specified to do you will get lower efficiency on powdered iron .When I run powdered iron I set up for very low ripple currents to make core losses very low .





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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3














    There is a color standard for painted toroids, and yellow means it has hysteresis to prevent saturation and is meant for filter inductors. But a side effect is that it has very low permeability. Black ferrite is usually a good choice for transformers. Blue is an expensive Permalloy that is more efficient than ferrite. Green is low frequency filters made with silicon steel tape wrapped to form a toroid.



    This chart is generic as it is not including fine details such as permeability, and does not state if iron, steel, ferrite or permalloy, which is a nickel-iron alloy.



    PC power supplies can put out over 1,000 watts and they use E cores as they are easy to wind by machine, and can have a cross section large enough to handle as much as 10 ampere/turns, and a tiny 10 mil air gap helps a lot. Large toroids need expensive winding machine heads so toroids are better used at low voltages were the number of windings is low, such as car stereo power supplies.



    NOTE: Sometimes practical reasons determine what material and shape of transformer are used, which is not always the best choice. Cost and size compete with efficiency. The opinions of engineering and marketing and sales are not the same, and who wins determines what is used. "Just good enough" wins most of the time.



    enter image description here






    share|improve this answer























    • And what about the unpainted black ferrites? That's the cheapest one at my place. One can also see them inside CFL lamps. I already know they work at low currents very well with a MC34063, and also as jewel thief. But how about 3A buck converter with LM2596?
      – Indraneel
      46 mins ago












    • For a given design based on a PWM IC the manufacture often specifies core material or a part number that you can search with. There a many toroid manufactures all over the world.
      – Sparky256
      37 mins ago










    • Well, the LM2596 datasheet says ferrite E core or ferrite bobbin or powdered iron toroid. So, is this because the peak current is already too high for ferrite cores without an air gap?
      – Indraneel
      28 mins ago










    • I added some more to my answer.
      – Sparky256
      3 mins ago
















    3














    There is a color standard for painted toroids, and yellow means it has hysteresis to prevent saturation and is meant for filter inductors. But a side effect is that it has very low permeability. Black ferrite is usually a good choice for transformers. Blue is an expensive Permalloy that is more efficient than ferrite. Green is low frequency filters made with silicon steel tape wrapped to form a toroid.



    This chart is generic as it is not including fine details such as permeability, and does not state if iron, steel, ferrite or permalloy, which is a nickel-iron alloy.



    PC power supplies can put out over 1,000 watts and they use E cores as they are easy to wind by machine, and can have a cross section large enough to handle as much as 10 ampere/turns, and a tiny 10 mil air gap helps a lot. Large toroids need expensive winding machine heads so toroids are better used at low voltages were the number of windings is low, such as car stereo power supplies.



    NOTE: Sometimes practical reasons determine what material and shape of transformer are used, which is not always the best choice. Cost and size compete with efficiency. The opinions of engineering and marketing and sales are not the same, and who wins determines what is used. "Just good enough" wins most of the time.



    enter image description here






    share|improve this answer























    • And what about the unpainted black ferrites? That's the cheapest one at my place. One can also see them inside CFL lamps. I already know they work at low currents very well with a MC34063, and also as jewel thief. But how about 3A buck converter with LM2596?
      – Indraneel
      46 mins ago












    • For a given design based on a PWM IC the manufacture often specifies core material or a part number that you can search with. There a many toroid manufactures all over the world.
      – Sparky256
      37 mins ago










    • Well, the LM2596 datasheet says ferrite E core or ferrite bobbin or powdered iron toroid. So, is this because the peak current is already too high for ferrite cores without an air gap?
      – Indraneel
      28 mins ago










    • I added some more to my answer.
      – Sparky256
      3 mins ago














    3












    3








    3






    There is a color standard for painted toroids, and yellow means it has hysteresis to prevent saturation and is meant for filter inductors. But a side effect is that it has very low permeability. Black ferrite is usually a good choice for transformers. Blue is an expensive Permalloy that is more efficient than ferrite. Green is low frequency filters made with silicon steel tape wrapped to form a toroid.



    This chart is generic as it is not including fine details such as permeability, and does not state if iron, steel, ferrite or permalloy, which is a nickel-iron alloy.



    PC power supplies can put out over 1,000 watts and they use E cores as they are easy to wind by machine, and can have a cross section large enough to handle as much as 10 ampere/turns, and a tiny 10 mil air gap helps a lot. Large toroids need expensive winding machine heads so toroids are better used at low voltages were the number of windings is low, such as car stereo power supplies.



    NOTE: Sometimes practical reasons determine what material and shape of transformer are used, which is not always the best choice. Cost and size compete with efficiency. The opinions of engineering and marketing and sales are not the same, and who wins determines what is used. "Just good enough" wins most of the time.



    enter image description here






    share|improve this answer














    There is a color standard for painted toroids, and yellow means it has hysteresis to prevent saturation and is meant for filter inductors. But a side effect is that it has very low permeability. Black ferrite is usually a good choice for transformers. Blue is an expensive Permalloy that is more efficient than ferrite. Green is low frequency filters made with silicon steel tape wrapped to form a toroid.



    This chart is generic as it is not including fine details such as permeability, and does not state if iron, steel, ferrite or permalloy, which is a nickel-iron alloy.



    PC power supplies can put out over 1,000 watts and they use E cores as they are easy to wind by machine, and can have a cross section large enough to handle as much as 10 ampere/turns, and a tiny 10 mil air gap helps a lot. Large toroids need expensive winding machine heads so toroids are better used at low voltages were the number of windings is low, such as car stereo power supplies.



    NOTE: Sometimes practical reasons determine what material and shape of transformer are used, which is not always the best choice. Cost and size compete with efficiency. The opinions of engineering and marketing and sales are not the same, and who wins determines what is used. "Just good enough" wins most of the time.



    enter image description here







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited 4 mins ago

























    answered 48 mins ago









    Sparky256Sparky256

    11.2k21635




    11.2k21635












    • And what about the unpainted black ferrites? That's the cheapest one at my place. One can also see them inside CFL lamps. I already know they work at low currents very well with a MC34063, and also as jewel thief. But how about 3A buck converter with LM2596?
      – Indraneel
      46 mins ago












    • For a given design based on a PWM IC the manufacture often specifies core material or a part number that you can search with. There a many toroid manufactures all over the world.
      – Sparky256
      37 mins ago










    • Well, the LM2596 datasheet says ferrite E core or ferrite bobbin or powdered iron toroid. So, is this because the peak current is already too high for ferrite cores without an air gap?
      – Indraneel
      28 mins ago










    • I added some more to my answer.
      – Sparky256
      3 mins ago


















    • And what about the unpainted black ferrites? That's the cheapest one at my place. One can also see them inside CFL lamps. I already know they work at low currents very well with a MC34063, and also as jewel thief. But how about 3A buck converter with LM2596?
      – Indraneel
      46 mins ago












    • For a given design based on a PWM IC the manufacture often specifies core material or a part number that you can search with. There a many toroid manufactures all over the world.
      – Sparky256
      37 mins ago










    • Well, the LM2596 datasheet says ferrite E core or ferrite bobbin or powdered iron toroid. So, is this because the peak current is already too high for ferrite cores without an air gap?
      – Indraneel
      28 mins ago










    • I added some more to my answer.
      – Sparky256
      3 mins ago
















    And what about the unpainted black ferrites? That's the cheapest one at my place. One can also see them inside CFL lamps. I already know they work at low currents very well with a MC34063, and also as jewel thief. But how about 3A buck converter with LM2596?
    – Indraneel
    46 mins ago






    And what about the unpainted black ferrites? That's the cheapest one at my place. One can also see them inside CFL lamps. I already know they work at low currents very well with a MC34063, and also as jewel thief. But how about 3A buck converter with LM2596?
    – Indraneel
    46 mins ago














    For a given design based on a PWM IC the manufacture often specifies core material or a part number that you can search with. There a many toroid manufactures all over the world.
    – Sparky256
    37 mins ago




    For a given design based on a PWM IC the manufacture often specifies core material or a part number that you can search with. There a many toroid manufactures all over the world.
    – Sparky256
    37 mins ago












    Well, the LM2596 datasheet says ferrite E core or ferrite bobbin or powdered iron toroid. So, is this because the peak current is already too high for ferrite cores without an air gap?
    – Indraneel
    28 mins ago




    Well, the LM2596 datasheet says ferrite E core or ferrite bobbin or powdered iron toroid. So, is this because the peak current is already too high for ferrite cores without an air gap?
    – Indraneel
    28 mins ago












    I added some more to my answer.
    – Sparky256
    3 mins ago




    I added some more to my answer.
    – Sparky256
    3 mins ago













    1














    Powdered Iron is Cheap and more forgiving when it comes to saturation due to the more gradual BH curves .There is a down side when for Buck and most other DC/DC convertors .The inductor ripple current will cause more core losses in the powdered iron than in most ferrites .It is quite normal to have AC ripple currents at about 33% of the max DC load current .So on an orthodox hardswitched peak current mode switching regime which most easy to buy chips are specified to do you will get lower efficiency on powdered iron .When I run powdered iron I set up for very low ripple currents to make core losses very low .





    share


























      1














      Powdered Iron is Cheap and more forgiving when it comes to saturation due to the more gradual BH curves .There is a down side when for Buck and most other DC/DC convertors .The inductor ripple current will cause more core losses in the powdered iron than in most ferrites .It is quite normal to have AC ripple currents at about 33% of the max DC load current .So on an orthodox hardswitched peak current mode switching regime which most easy to buy chips are specified to do you will get lower efficiency on powdered iron .When I run powdered iron I set up for very low ripple currents to make core losses very low .





      share
























        1












        1








        1






        Powdered Iron is Cheap and more forgiving when it comes to saturation due to the more gradual BH curves .There is a down side when for Buck and most other DC/DC convertors .The inductor ripple current will cause more core losses in the powdered iron than in most ferrites .It is quite normal to have AC ripple currents at about 33% of the max DC load current .So on an orthodox hardswitched peak current mode switching regime which most easy to buy chips are specified to do you will get lower efficiency on powdered iron .When I run powdered iron I set up for very low ripple currents to make core losses very low .





        share












        Powdered Iron is Cheap and more forgiving when it comes to saturation due to the more gradual BH curves .There is a down side when for Buck and most other DC/DC convertors .The inductor ripple current will cause more core losses in the powdered iron than in most ferrites .It is quite normal to have AC ripple currents at about 33% of the max DC load current .So on an orthodox hardswitched peak current mode switching regime which most easy to buy chips are specified to do you will get lower efficiency on powdered iron .When I run powdered iron I set up for very low ripple currents to make core losses very low .






        share











        share


        share










        answered 7 mins ago









        AutisticAutistic

        7,31121532




        7,31121532






























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