Heatsinks for Bosoz?

Kari · 13th March 2005, 11:05 AM

Hi,
as i'm currently drawing pcb for a X-Bosoz with ccs i'm wondering if a heatsink is required? Acording to my cim about 40mA is floating trough each of the diffpair fets and around 80-100ma trough the ccs. 60V * 0,04A = 2,4W for the diff fet and i recon that it should work without a heatsink, right? For the ccs the figures would be 9V* 0.1A = 0.9W.

Any comments?

Thx,

Kari

metalman · 13th March 2005, 05:38 PM

Kari,

I think you will definitely want heatsinks. For my BZLS variation I used my aluminum chassis as the heatsink for all my FET's, and the chassis is noticeably warm to the touch when operating. Check the datasheets for the IRF610 for heat transfer from package to air as a check, as I may have been overcautious, but I'm pretty sure I did the check and found the FET's would overheat.

Cheers, Terry

Kari · 13th March 2005, 07:48 PM

Thx Terry,
I checked the datasheet and according to that the fets would run at 2,4 * 62 = 148 deg C

. However, the adding of heatsinks did screwup my symmetry a little bit......

/Kari

steenoe · 14th March 2005, 06:58 AM

Very interresting layout, Kari

Are you planning on using MKP's
for the caps? Its quite roomy for the caps on the pcb. Looks good

Steen.

Kari · 14th March 2005, 03:00 PM

The footprints for the caps are Mundorf MCap 33uF + some odd mm to both axis. This way i get to experiment with different caps.

I've also moved the ccs fet in the "middle" of all three so now i have a more symmteric layout. I'll post a pic as soon as i get home.

/Kari

Kari · 14th March 2005, 05:21 PM

Here's a pic of the updated board.

/Kari

steenoe · 14th March 2005, 06:33 PM

Beautyful

Very symmetric layout. Are you considering a PSU board also?

Steen.

Kari · 14th March 2005, 08:03 PM

Yep, i will do a psu board also. I was first considering to integrate everything to the same board (cheaper) but desided to make two boards instead.

/Kari

steenoe · 14th March 2005, 08:20 PM

Quote:

desided to make two boards instead.

That is propably a good idea

Gives you flexibilty if you want to move the PSU to a separate chassis. (like me for one)

Is the connection pads layed out for terminal blocks?

Steen.

Coulomb · 15th March 2005, 03:41 AM

Quote:

Originally posted by Kari
Yep, i will do a psu board also. I was first considering to integrate everything to the same board (cheaper) but desided to make two boards instead.

/Kari

Will you make some boards available to others, Group Buy maybe?

Anthony

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13th March 2005, 05:38 PM	#2
metalman diyAudio Member Join Date: Jun 2003 Location: Calgary, Alberta	Kari, I think you will definitely want heatsinks. For my BZLS variation I used my aluminum chassis as the heatsink for all my FET's, and the chassis is noticeably warm to the touch when operating. Check the datasheets for the IRF610 for heat transfer from package to air as a check, as I may have been overcautious, but I'm pretty sure I did the check and found the FET's would overheat. Cheers, Terry

14th March 2005, 06:58 AM	#4
steenoe diyAudio Member Join Date: Mar 2004	Very interresting layout, Kari Are you planning on using MKP's for the caps? Its quite roomy for the caps on the pcb. Looks good Steen.

14th March 2005, 03:00 PM	#5
Kari diyAudio Member Join Date: Jan 2004 Location: Stockholm	The footprints for the caps are Mundorf MCap 33uF + some odd mm to both axis. This way i get to experiment with different caps. I've also moved the ccs fet in the "middle" of all three so now i have a more symmteric layout. I'll post a pic as soon as i get home. /Kari

14th March 2005, 06:33 PM	#7
steenoe diyAudio Member Join Date: Mar 2004	Beautyful Very symmetric layout. Are you considering a PSU board also? Steen.

14th March 2005, 08:03 PM	#8
Kari diyAudio Member Join Date: Jan 2004 Location: Stockholm	Yep, i will do a psu board also. I was first considering to integrate everything to the same board (cheaper) but desided to make two boards instead. /Kari

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