Electronics > Projects, Designs, and Technical Stuff
DC load using a CPU cooler
microbug:
I got a reply from Delta Components in the UK. They have a sister company, Neutron LLP, that will provide me with two IXTH75N10L2 samples free of charge :)
Mr.B:
--- Quote from: rob77 on October 14, 2014, 06:36:02 am ---check the datasheet for thermal de-rating factor - it might be a surprisingly high number (a 100W mosfet can easilly become 40W max at high temperatures)
--- End quote ---
Checking the datasheet, I cannot see anything directly called thermal de-rating factor - unless I am overlooking something.
The IXTH30N50L2 is quoted as a 400W device (when Tc = 25 deg C).
If I take the quoted SOA: 200W @ Tc = 75 deg C.
RthJC is 0.31 deg C/W.
200 * 0.31 = 62 deg.
Therefore: 75 + 62 = 137 deg C for the junction temperature when the case is 75 deg C and I am driving it at 200W.
I plan to drive the device at a maximum of 150W.
Assuming 137 deg C is within the SOA and working backwards...
150 * 0.31 = 46.5 deg C.
137 - 46.5 = 90.5 deg C.
To remain within SOA, I can allow the case temperature to be as high as 90.5 deg C @ 150W.
Now add to this the RthCS of 0.25 deg C/W --> 150 * 0.25 = 37.5 deg.
90.5 deg (case) - 37.5 deg = 53 deg.
If my math above is correct...
I can allow my heatsink face to get to 53 deg C if I am driving the FET at 150W.
Have I understood this correctly?
Jeroen3:
IXYS is very honest and they specify their SOA at Tc 75.
They do not specify a dereting factor. But this fet is designed for linear use.
If you stay inside the soa drawn in Fig. 14 you should be fine.
Mr.B:
--- Quote from: Jeroen3 on October 14, 2014, 10:09:17 am ---I was looking at the linearity of the Id/Vgs curve. It's not ideal if the fet goes from 0 to Imax in a window less than 1 Volts.
The IXTP or IXTH15N50L2 seems nice for this purpose, you have less risk of instability when you're running milliamps.
And it's affordable on digikey and an ebay seller.
I'll look into the ones named above tonight. (EU time)
--- End quote ---
Sorry Jeroen3, I dont quite follow you.
The graph for the IXTH30N50L2 looks to me to be about 3.5v for the 10A Ids range I want to run mine in.
Am I missing something here?
Mr.B:
--- Quote from: Jeroen3 on October 14, 2014, 07:44:26 pm ---IXYS is very honest and they specify their SOA at Tc 75.
They do not specify a dereting factor. But this fet is designed for linear use.
If you stay inside the soa drawn in Fig. 14 you should be fine.
--- End quote ---
Thanks, will do.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version