T
treez
Guest
Hello,
We are designing a sync Buck converter with..
Vin = 28V
Vout = 1V5
Iout = 17.1 A
F(sw) = 200kHz
There are eight of these with outputs all paralleled.
The inductor is 1uH and is the IHLP5050CE-01 type (datasheet below). This SMPS is in a totally sealed enclosure with the internal ambient at 70degC. There is however, a cold plate, which is gap-padded to the inductors and FETs. The FETs are BSC027N04 (datasheet below). Obviously we are heatsinking the FETs wrong because these FETs are designed to put heat into the PCB via their heat pad, and not meant to conduct heat to a heatsink up through their plastic bodies.
The problem is that the inductor datasheet does not give the thermal conductivity for the iron powder material that it is made of. Therefore, we are not sure how much hotter the inductor will be than the cold plate in parts of the inductor which are away from the cold plate. Also, each inductor has 1.7W of loss in its windings, and 0.4W of loss in its core. Therefore, we really need to know the thermal conductivity of the inductor core because then we can have some idea of how much of the winding heat will conduct through the core and from there to the cold plate via the gap pad.
If the core is quite thermally insulative then the windings heat will just conduct mostly into the PCB and heat that up, which will heat up the FETs even more.
So do you know what is the thermal conductivity of the IHLP material of the inductor?
The below has thermal conductivity of a different iron powder than IHLP material as being at least ten times less than that of aluminium…that’s not good..what’s it like for IHLP material?…
Page 5 shows general iron powder thermal conductivity…
**broken link removed**
BSC027N04 FET datasheet:-
https://www.infineon.com/dgdl/Infin...n.pdf?fileId=db3a30431689f4420116c4323646080c
IHLP5050CE-01 inductor datasheet:-
**broken link removed**
We are designing a sync Buck converter with..
Vin = 28V
Vout = 1V5
Iout = 17.1 A
F(sw) = 200kHz
There are eight of these with outputs all paralleled.
The inductor is 1uH and is the IHLP5050CE-01 type (datasheet below). This SMPS is in a totally sealed enclosure with the internal ambient at 70degC. There is however, a cold plate, which is gap-padded to the inductors and FETs. The FETs are BSC027N04 (datasheet below). Obviously we are heatsinking the FETs wrong because these FETs are designed to put heat into the PCB via their heat pad, and not meant to conduct heat to a heatsink up through their plastic bodies.
The problem is that the inductor datasheet does not give the thermal conductivity for the iron powder material that it is made of. Therefore, we are not sure how much hotter the inductor will be than the cold plate in parts of the inductor which are away from the cold plate. Also, each inductor has 1.7W of loss in its windings, and 0.4W of loss in its core. Therefore, we really need to know the thermal conductivity of the inductor core because then we can have some idea of how much of the winding heat will conduct through the core and from there to the cold plate via the gap pad.
If the core is quite thermally insulative then the windings heat will just conduct mostly into the PCB and heat that up, which will heat up the FETs even more.
So do you know what is the thermal conductivity of the IHLP material of the inductor?
The below has thermal conductivity of a different iron powder than IHLP material as being at least ten times less than that of aluminium…that’s not good..what’s it like for IHLP material?…
Page 5 shows general iron powder thermal conductivity…
**broken link removed**
BSC027N04 FET datasheet:-
https://www.infineon.com/dgdl/Infin...n.pdf?fileId=db3a30431689f4420116c4323646080c
IHLP5050CE-01 inductor datasheet:-
**broken link removed**
