Visiting and talking with Zen V9...

[Winding Man]

Been a while - I bought the heatsinks, the PCBs and the Fets etc in 2007 - or sometime then - so now I figure it really is time to put her together....

But - yes there is always a 'but' I guess - I want to extract more power and I have seen and read the 50W Zen V9 thread - maybe my ramblings should be in that thread but maybe not as that is not quite the way I wanted to go...

Given that the main devices can handle 200V and 20A - is it not feasible to just up the PSU Voltage and current capability.....and heatsinking....?


WM

[eyoung]

I think you can do that but you must observe first stage transistors may exceed rated voltage for those so regulate down or cascode or both. I am sure there are others that have been there done that...

Regard, El

[h_a]

is it not feasible to just up the PSU Voltage and current capability.....and heatsinking....?

No.

Problem is, the little LU-fet comes in such a tiny package, so that it's hard to get more than 5W or so away from it (see also original article).

Hannes

[Winding Man]

Thanks for the comments thus far guys...

Originally Posted by h_a

No.

Problem is, the little LU-fet comes in such a tiny package, so that it's hard to get more than 5W or so away from it (see also original article).

Hannes

I understand pity as it is rated 24V at 50A - wow yes small device given those ratings....

WM

[dave_gerecke]

Hello WM, as you observed, they are rated for 24V @ 50A, but not both at the same time. If you look at the datasheet for a device, these are maximum ratings at each extreme. The important spec to look at in regards to your question is the Power Dissipation. This, along with the previous specs, determines what your transistor can handle in steady state(which Class A is).

Peace,

Dave

[Winding Man]

Thanks Dave - I am a tube guy so this solid state foray is all new to me although I guess thats no excuse I should pay more attention to the data sheets!

Ta

WM

[flg]

Also, most ratings are at 25C. Typically, in operation, we would be running 65-95C die temp.
I've had the LU part biased at 3A and 2.5V for a year without problems.

[Winding Man]

Originally Posted by flg

Also, most ratings are at 25C. Typically, in operation, we would be running 65-95C die temp.
I've had the LU part biased at 3A and 2.5V for a year without problems.

Thanks flg....

Any advances on 7.5W?

I guess then that the mounting of the device and the resultant thermal resistance to the heatsink requires investigation/optimisation.

WM

[flg]

I have it mounted with no isolator, directly on an anadized sink, and Arctic Silver 5 compound.

[Winding Man]

Originally Posted by flg

I have it mounted with no isolator, directly on an anadized sink, and Arctic Silver 5 compound.

Yes! Thats a great idea!

Does this device need to be at the same temp as the main Fets as some sort of tracking thermal compensation mechanism or can it be on its own?

Thinking of a separate heat sink heat pipe approach here....?

Ta

WM