[ulihuber]

Hi Syp,

if you look at the low side, it could be possible. The IR2184 however includes Push-Pull-Drivers which takes care of high speed charge and discharge of the gate capacity. Without these, power dissipation would increase dramatically.

If you look at the high side, it's not only the question of sped. You have a floating source and a gate which must be at positive charge to switch the MOSFET.

In addition the IR2184 contains a circuit for the deadtime and undervoltage protection. It's not at all an easy task to build that discrete and consumes a lot of parts and space on the board.

Look into the datasheet and you'll understand what I am talking about.

Uli


BTW: How do I post a picture here ?

[Syp]

Hi!

Thanks, but that was not really what I was asking. I know the need for the IR2184 to drive the HUGE capacitance of the power mosfet gate. This is not in question. Even for the low side mosfets, something would be needed to interface between the dinky 20mA output of the atmel and the power mosfet gate...or have the gate take many many microseconds to turn on = poof!

No, what I was asking was the purpose of the 4 components (2 resistors, 1 diode, 1 capacitor) between the drive output of the IR2184 and the gate of the power mosfet.

Very sorry if I was not too clear in first post.

Thanks!

Syp

[ulihuber]

Syp,

it's my fault, I read to fast...

Let me just cite the IR application note:
"The resistor-diode network is also useful in reducing the peak of the current spike during the reverse recovery time. As explained in Ref. 2, this has an impact on power losses, as well as dv/dt and EMI."

Uli

[Syp]

Uli!

Ah! I did not know of this application note of which you speak. I will have to peruse the International Rectifier page to find it!

Thanks!

Syp

[jlcortes]

Hi

I have received the SMD boards, I am wishing to mount and test my fisrt prototype.
I have designed a industrial look enclusure, it is laser cut and hand bend.

[bigandy]

That enclosure looks pretty neat! have you got anymore information on it? Such as material thickness, sizes etc etc?

Cheers
Andy

[jrz126]

Looks great!
How big of a motor are you planning on driving? I'd be alittle concerned about power disipation with those surface mount mosfets.

[Xerxes]

Ah! I did not know of this application note of which you speak. I will have to peruse the International Rectifier page to find it!

Sounds like a very useful application note. Let us know if you find it! :-)


jlcortes: Great looking work! Any ideas how much it would cost to manufacture such enclosures?

[jlcortes]

my motors are 260VDC 5A (1300W), I think it is too much for the SMD design but i try it. I can make a future version with DIP IGBTs screwed to my aluminium enclosure.

The enclosure is 2 mm thickness aluminium sheet, it is a single sheet with some (hand)bends.

bigandy send me your email and i send you the autocad file.

[jlcortes]

Xerxes: about cost, it is very cheap, 69€ - 11 units. I was thinked about paint in black and put a sticker and give a profesional look!

[ulihuber]

Jose,

thats a piece of cake !
Both, the board and the casing.

Great work !
Uli

[micromillnick]

Fantastic!, at last someone has come up with a DIY servocontroller, i mentioned this about 2 years agoa nd got shot down in flames, couldnt be done they said!.

Nick

[Syp]

The gecko was DIY...or at least I don't think Marriss has help in it's design. I believe he already had experience designing Centent stepper drives though...

[Goat]

If anyone runs into heat problems...I work for a heatsink manufacturer and can supply cooling solutions. PM me if you need a heatsink.

[ulihuber]

Hi all,

concerning the heat sink, consider to use a rectangular shaped piece of Aluminium, about 90mm x 30mm x 8mm. This will be enough for small motors as power dissipation is really small and power peeks get sufficiently absorbed.
If you are going in higher current applications, screw a flat heat sink on top of this Aluminum bar.
Doing so, you have the advantage to reach the components under the heat sink without screwing off all the transistors. Compared to a L-shaped heat sink this helps a lot if you encounter any trouble and want to measure or replace components.

Don't forget to add this white heat conducting stuff in between the two parts of the heat sink...


Uli

[Dan Mauch]

if anyone wants to go in with me and get some of these pcb's made, get some chips from uli and split on the cost of a bulk parts purchace ....
pm me

I just joined this forum and was wondering if anyone has made a batch of the boards? If are they still availble? How do I order them?
I ordered some of the controller chips and can etch my own though I much rather have commercial made boards.

Dan

[turmite]

Hi Dan,
Below is a quote from the fellow here in the states that has the parts.

Mike

Hello All,

- The Kit which contains everything to build a uHu servo controller (IRF540's)

will cost $ 119.00 US.

- Assembled and tested uHu servo controller

will cost $ 149.00 US.

Please visit www.bgmikro.com for the latest updates.

- 100 units should be available on or about Jan.15,/06
- We will subtract $10.00 if you already have a uHu chip and $1.00 for a xtal.
ps: as some of you may have found some parts are hard to come by and have
to be purchaced in large quantities.
Thank you.

[vroemm]

I just joined this forum and was wondering if anyone has made a batch of the boards? If are they still availble? How do I order them?
I ordered some of the controller chips and can etch my own though I much rather have commercial made boards.

See "Professional made PCB" at the end of this page:
http://gsst.wikispaces.com/UHUget
http://gsst.wikispaces.com

Its the PCB only, it does not include all the parts.

[smarbaga]

The kits are almost complete.
I am just waiting for the heatsink.

** after evaluating the total cost, i will have to charge:

Kit - $ 109.00 us.
Assembled - $ 119.00 us.

I suspect the heatsink to be here on Feb. 3, 2006.
I will have 100 Units for sale.

See Attachment

[geoffd]

I just ordered some boards from Stefan and he said that he should have some next week.

Cheers
Geoff

See "Professional made PCB" at the end of this page:
http://gsst.wikispaces.com/UHUget
http://gsst.wikispaces.com

Its the PCB only, it does not include all the parts.