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-   -   Semisouth SJEP120R100 Power Loss (http://www.diyaudio.com/forums/pass-labs/178050-semisouth-sjep120r100-power-loss.html)

spavleski 28th November 2010 06:55 AM

Semisouth SJEP120R100 Power Loss
 
Playing a bit with SJEP120R100 seems to me that warming of a heatsink is much less in comparison to IRFPN150, although both of them were using the same supply power and were put under the same operating conditions (Id = 2A).

According to my understanding, most obviously this is thanks to the superb SJEP120R100 design which proves to be high efficiency and minimal loss devices. :)

Really seems that SIC is very promising new technology.

Does anyone playing with SJPE120R100 have similar feelings about thermal power losses?

alexberg 28th November 2010 07:20 AM

Does your amplifier absorb the energy out of free space and transfer it to the load?;)
P1=I*U
P2=I*U
if right parts of the equations are equal, then the left parts are and so be it...
The article you are referring to is about switch mode converters.

spavleski 28th November 2010 07:25 AM

The story is replacing Babelfish with Babelfish J2. Heatsinks seems to warm less, now. Searching for the explanation, I found a lot of articles claiming SIC technology advantages in terms of Thermal losses compared to normal Si power Mosfet. Knowing that there are now a number of people that are playing with SJEP120R100, I just wanted to check my observation.

chip_mk 28th November 2010 05:48 PM

Power dissipation is Pd = Vds x Id no matter what type of FET is used. Given the same operating conditions IRFPN150 and SJEP120R100 will dissipate equally. Difference might appear if transistor start to oscillate or due to unequal thermal resistance of transistor cases.

Talking about Semisouth devices, I’m curious, have you noticed any gate current in idle mode (with no AC signal)? This can be checked by measuring voltage drop across the gate resistor. Will you please check this, I’m curious?

spavleski 28th November 2010 06:37 PM

Quote:

Originally Posted by chip_mk (Post 2380047)
Power dissipation is Pd = Vds x Id no matter what type of FET is used. Given the same operating conditions IRFPN150 and SJEP120R100 will dissipate equally. Difference might appear if transistor start to oscillate or due to unequal thermal resistance of transistor cases.

Talking about Semisouth devices, Im curious, have you noticed any gate current in idle mode (with no AC signal)? This can be checked by measuring voltage drop across the gate resistor. Will you please check this, Im curious?

Thanks for nice explanation. In the mean time, I understood that I was wrong. Most probably, new liskuns were too fat and temperature measured on heatsink was 42 degree, and measured directly on case of SJEP120R100 was 70 degree. Liskun used now is thinner, and I expect little increase of the heatsink temperature. Also, I checked the Bias, and seems that it is 1,85A instead of 2A. Those two things guided me to have wrong conclusion. Anyhow, I promise to measure voltage over the Gate Resistor in idle mode and will post it here in an hour or two.

Zen Mod 28th November 2010 06:49 PM

naah

my fullrange bro spavleski was tired of busting working tempo in last few months

besides - he's familar now with ZM's natural state - fooked brain

good thing is that in his case that was just temporary ....... :rofl:

btw. liskun - means - mica

spavleski 28th November 2010 07:06 PM

Hm...confused...All gate resistors are 100 Ohms. Measured voltage in idle mode is 300 mV over one gate resistor and 6 mV over the other. Measured on both channels - the same situation - One 300mV, other 6mV. :confused:

Zen Mod 28th November 2010 07:10 PM

which one 0V3 , which one 6mV ?

spavleski 28th November 2010 07:12 PM

1 Attachment(s)
Quote:

Originally Posted by Zen Mod (Post 2380141)
which one 0V3 , which one 6mV ?

V over R32 300mV
V over R27 6 mV

Zen Mod 28th November 2010 07:20 PM

you know what ?

who cares .......

:rofl:

maybe in a day or two I'll find time to check on my working channel


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