Mastero MK-4 ATX PSU with features. - Page 3

Ricky327 · 04-27-2004, 10:10 PM

I am not whatever it is you called me

I wasnt so sure either...anyway heres the dictionary.

http://english2american.com/dictionary/cat_insults.html

It says Im supposed to be jealouse of your boringness

Its just that considering we (as a community) have nothing but OPUS, a new PSU is really interesting but the thread is being updated with garbage, which inturn updates my e-mail with the same quality crap

Point taken...back to reality

Crimson Tear · 04-28-2004, 12:47 AM

Sorry about the garbage, but... LOL! an English to American dictionary!

Mastero · 04-28-2004, 02:30 AM

Ok guys i like humor, but not on this thread..

I dont want to make the thread big with just silly humor.

"If your not part of the solution dont be the cause of my problem"

I would like it if you all could delete the silly posts. ASAP

Mastero

rando · 04-28-2004, 09:39 PM

Quote: Originally Posted by Mastero

Post your opinions and views here.

Can you explain how you chose the output inductor and and capacitor values for the LM2678T? The nomograph from the spec sheet suggests a 15uH inductor for the operating conditions (8-16v input, 5A max load). Webench selects a 12uH for the same conditions at 30C.

I assume smaller inductors are less expensive, make layout a bit easier, and save space on your circuit board. Maybe this design decision was based more on the fact that you happen to have the 47uH parts lying around (from the MK3.5).

Feel free to smack me around if I'm not making any sense.

BTW, I'm eager to see any updates you have.

Mastero · 04-29-2004, 02:19 AM

Quote: Originally Posted by rando

Can you explain how you chose the output inductor and and capacitor values for the LM2678T? The nomograph from the spec sheet suggests a 15uH inductor for the operating conditions (8-16v input, 5A max load). Webench selects a 12uH for the same conditions at 30C.

I assume smaller inductors are less expensive, make layout a bit easier, and save space on your circuit board. Maybe this design decision was based more on the fact that you happen to have the 47uH parts lying around (from the MK3.5).

Feel free to smack me around if I'm not making any sense.

BTW, I'm eager to see any updates you have.

Rando the MAX 787 . LT1074, LM2678 are all identical chips in cuircuts.. the Chips will work in smaller inductor but the use off inductor here is to store current during the switching process of the regulator. so a 47uh will give better performance than the 12uh.

The national have mentioned 8~16 they dont say a irregular input they presume you are using a constant volt within the given range.

I hope it helps ..

Mastero

rando · 04-29-2004, 02:57 AM

If I'm reading the layout correctly, it looks like the STBY now draws its current from the +12v IN instead of ACC. That's a nice improvement over the MK3.5. Drawing more than a few milliAmps from ACC probably isn't a good idea. Also, it looks like J1 gives the option to have STBY always on (like on the Opus) or switched with ACC. If that's true, this should come in handy for those folks who are having problems with rogue devices sucking current from STBY when their computer is off.

As another suggestion, are you working on a solution to eliminate the relays. There are 3 of them on board now.

All in all, this looks promising Mastero. The more I look at it, the more I like it. Gotta admit though, the current layout isn't a thing of beauty yet.

rando · 04-29-2004, 03:01 AM

Quote: Originally Posted by Mastero

so a 47uh will give better performance than the 12uh.

OK, I understand but if a smaller inductor can give the needed performance, there are other things that could be gained by going smaller. A smaller inductor saves space, costs less, increases layout flexibility, and generates a smaller magnetic field. The latter issue is fairly significant given the planned use for this PSU in an a/v environment.

Regardless, I trust you've got it all worked out. More importantly, I've already got a set of the 47uH ones on my desk. So either way, I'm happy.

MatrixPC · 04-29-2004, 01:15 PM

Rando, as of the beginning, the relay next to the sproggy relay is NOT there. There is a problem I found out that if the STBY chip get hot but no ground (SDC circuit supplies ground to the chip), the output is the same as input. Thus the STBY voltage is whatever the input is (battery voltage in this case). In another word, if the SDC supply ground to the STBY chip, the output is 5V, but no ground, the output is 12+V. And if there is output on STBY, the mobo will always be on. Mastero and I talk abou that so we just use a relay. The SDC circuit driven the relay, and in turn the relay supply power/current to the STBY.
The relay on the bottom of the board is controlling low voltage shutdown circuit. If low voltage is detected, the relay cut the ACC input so that the SDC will shutdown the Computer and PSU.

rando · 04-29-2004, 01:32 PM

OK, I wasn't talking about the relay (though i did wonder why it was there). I was only pointing out, for the sake of others, that the STBY current is now sourced from the supply +12V IN, instead of ACC. That's true, right?

MatrixPC · 04-29-2004, 01:39 PM

Correct. But the current have to go thru the relay

BraGa · 04-29-2004, 07:30 PM

[quote]Uses all national chips for voltage converting.
Hi all! First time poster... keep up the good job :-)

My question is:
In the Mk4, can i still use the MAX chips? Or just the national ones?

Thanks

MatrixPC · 04-30-2004, 01:20 AM

Quote: Originally Posted by BraGa

Uses all national chips for voltage converting.
Hi all! First time poster... keep up the good job :-)

My question is:
In the Mk4, can i still use the MAX chips? Or just the national ones?

Thanks

NO, MAX chips only have 5 pins. National Chips have 7 pins, put only used 5 pin.

To everyone who still have the MAX chips. I will have to fix the SDC circuit and low voltage shutdown to what Mastero have on the MK4. After I am done, you are good to go.
My custom Mk3.5 is base on the Max chip from Mk3.5 and the new 12V section from Mk4.

rando · 04-30-2004, 02:48 AM

The National chips actually use 6 of the 7 pins. It's just that one of the pins (on/off) is not used in the MK4 design posted by Mastero. If he intregrates the TPS3510 controller, then I suspect he might end up using that extra pin after all since it might allow him to eliminate the main relay.

In any case, you can always concoct your own design that takes the 3.3 and 5v Maxim-IC sections from the Mk3.5 and the 12V, -12, -5, stby, pg, and SDC from the mk4. Of course then you'd have to make your own board layout and do your own etching.

Mastero · 04-30-2004, 03:00 AM

The reason for using national chips is so people can scource if from one place and national has a nice $ree samples rule easy and fast.

Mastero

MrPerfectionest · 04-30-2004, 08:01 AM

Will a schematic be availible anytime soon?