Beta Testers Needed.

[wasabe64]

Wayne, I can probably take a run at it.

Can you sent me the BOM? I'll have a look at it and see if I can source the parts quickly.

 

[NewBie]

[ QUOTE ]
Doug S said:
[ QUOTE ]
dat2zip said:
At the rate I'm toasting the boards, there won't be any to send to any testers. Two have shorts under the IC, one doesn't light and I've got one good one so far.

[/ QUOTE ]
Wayne, if it is any consolation, some of those new TI switcher IC's have been giving me fits too. Awhile back I laid out a circuit using one of their new stepdowns, the TPS62020, in that same leadless QFN10 package you are using [EDIT, whoops, bad memory. You are using a QFN-16 pkg. That's even harder to work with] . I toasted a pile of them. They would be stable under some Vin/Iout combinations but unstable under others. Once they went unstable, they generally died shortly. I finally set that circuit aside for now. I'll get back to it when I need some more aggravation. The only upside is that I got pretty good at changing out dead ICs for [briefly] good ones in that particular leadless package. A year ago I never would have dreamed I could do it.

[/ QUOTE ]

Running voltage mode, I have two flashlights one based on the TPS61020 and the other on the TPS61030, they have been working fine since January.

Implementing the current mode adds a whole new dimension to loop stability.

Another key thing is that it is absolutely critical to pay extremely close attention to the input and output current paths, and power ground and signal/analog ground.

Also keep in mind, if you are using one of the low voltage X7R or X5R, anywhere near their voltage ratings, their values drop drastically, much like the Y5U/Y5V do in the larger packages (the Y5U/Y5V are even worse in 0603/0402 in high value low voltage parts). I've seen a 6.3V X5R 10uf with only 2 uf of capacitance when a DC voltage is on it of 4V, and seen them drop to 1.5uF at their rated voltage. Luckily their ESR holds. I've spoken at length with folks at AVX/KEMET/MURATA about this, and have shown it to them, can you believe they acted surprised? We were using some very expensive equipment to demonstrate this. Keep this in mind when trying to compute the loop compensation, especially for type III compensation.

 

[mut]

/ubbthreads/images/graemlins/hahaha.gifHow about Sun ofa(BB)BadBoy for a name?/ubbthreads/images/graemlins/icon3.gif

mut

 

[balrog]

Hellboy sounds great! Would like to be a Beta tester but sadly, I have no bench supply. I'm surprised not to see CM post here...

 

[Billson]

Wayne,

Is testing still going on with this board? Any projections on when it'll be released?

 

[kj]

I'm also anxiously waiting for this... Any update would be appreciated /ubbthreads/images/graemlins/smile.gif

 

[CM]

[ QUOTE ]
balrog said:
Hellboy sounds great! Would like to be a Beta tester but sadly, I have no bench supply. I'm surprised not to see CM post here...

[/ QUOTE ]

Ha, I'm back (sort of). I've got the required equipment for beta testing. I volunteer to be a lab rat if you need one.

CM

 

[cgpeanut]

I'm very much interested in this board aswell please keep us updated Wayne. /ubbthreads/images/graemlins/popcorn.gif

 

[dat2zip]

I've had to shelve this one as I have two or three more urgent designs that take priority over this one.

The other thing that I've changed my mind on is sending out the raw boards. Since I have a bear of a time soldering or trying to solder the main IC on, I believe it will be nearly impossible for anyone else to succeed as well.

To save everyone the anguish and frustration of trying to bake this IC on, I've decided it's not worth it and it's too risky that it won't solder on properly.

I've done some 20 boards now of various types using this style IC and I'm getting the process down pretty good. Still, I have a very high failure rate of around 50% or less. Almost all of them require post touch up under the microscope and with no leads to solder is a real PIA.

I've got a list of all the ultra small tips, bevels, knifes from Metcal and I will be ordering many of them. I'm hoping that these will aide in soldering the 0402, 0201 and leadless ICs.

The new prototype of this IC has yet to yield any good results and I'm still at a roadblock. Of less concern is loop stability and I feel confortable with that.

Even tho I've been silent here on CPF, there has been good progress on many new projects in the R&D lab.

Wayne

 

[Billson]

Could you give us a teaser on what these new projects are?

 

[dat2zip]

I have two new IC's that were just released or soon to be released that will add to the product line new functionality that doesn't exist or is not well fitted with existing converter designs.

The Nexgen is an improved version of the Badboy more or less and thus, does not add new fuctionality.

I can't say much more than that. Some are close to limited run status, some have small runs already made and others are still on the drawing board.

Since there are an a vast sea of IC's out there it is wise to choose the best candidates that have the broadest possible usage.

Hopefully, I can share some additional info when appropriate.

Wayne

 

[AilSnail]

Hey I like the sound of Hellboy,
(almost as good as hound dog, but within the theme)
but since Jarhead named his tps61030 Thumper 1000 I just want to spell out
Rompin Stompin Hoochie Cooch Man !

Perhaps save it for the bigger brother though.

King Bee is nice too.

The smaller version you mentioned (is that a tps61020?) shall ofcourse be named
Honky Tonk Woman
/ubbthreads/images/graemlins/happy14.gif

 

[CNC Dan]

since this converter has two modes, I sugest: Gemini.

 

[rayearth]

I have some samples of the TI TPS61020DRCR chips and boy are they tiny. It's hard to appreciate how small they are until you have to squint at one. Leadless QFN packaging is a real PITA for hand soldering.

The finest Metcal tips are 0.4 mm wide, while the pads are about 0.25-0.3 mm wide. I've ground down a spare STTC-522 (Ebay is cheap!) tip from 0.4 mm down to about 0.1 mm or so. The problem is preventing the solder from overlapping the pads. I don't envy your job, Mr. Wayne. SOIC, even TSOP is easier.

I wonder if anyone has tried to use microscopic amounts of conductive epoxy instead of solder. I'm sure it has higher resistance, but when you talk about 0.05-0.1 mm thickness at the most, the added resistance may be negligible. Anyone have any experience with this?