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Teaser: The BlitzBuck - A 2A+ Switching Buck Driver

Owch! so CCurrent is out the window... without the jib
 
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I have some Jib drivers, and the negative input is the same trace as the negative output. Just like a DDL or other linear driver...

So that means that it is regulating through the positive side.

Not sure what rhd was referring to about that?? (unless he was isolating the case positive diode - or battery positive going through the driver before it connects to the host)

AMC7135 for an example, regulates through the negative side, and could be used in a case positive diode build, with battery case positive... (you would just need to make sure to isolate the driver negative edges from making contact with the main sink)

Which is not the ideal situation for that driver. Because it is best to heatsink the negative contacts... (edge of board)

And that is why that driver is best used in a situation like a flashlight, where the emitter is electrically isolated from the heatsink. (similar situation with 445's and 405 diodes)

If you some how thermal mount your IR diode, but keep it electrically isolated from the sink, then your good to go...
 
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Hey, so not to derail this discussion, but I have good news! I got 30 boards in the mail and will be doing assembly tomorrow afternoon. They should be shipped out to Clif on Monday :D
 
rhd said:
To clarify, when I said that "Jib" had a creative way to regulate case-positive builds with a continuous-negative driver, I meant "Jib" as in the person (not "Jib" as in "a Jib driver")

Here:
http://laserpointerforums.com/f67/h...-regulating-version-ddl-64955.html#post932922
Click to expand...

The case positive diode that is asking about is the problem...

That diagram of his won't work with a driver that is regulating through the positive side of the driver. (for a case positive diode like he is asking about) Not unless the diode is isolated from the supply like a 445, 405, or 635... (unless I'm not reading his diagram correctly)

Because with a linear driver (Jib, DDL, FlexModP3), the negative input and output are one and the same. So it's a direct connect from the negative supply to the diode.

Now if you also give a direct connect from the positive supply to the diode as that diagram shows, then it's the same as not even having a driver in there. It will by-pass the driver...
 
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jayrob said:
The case positive diode that is asking about is the problem...

That diagram of his won't work with a driver that is regulating through the positive side of the driver. (for a case positive diode like he is asking about) Not unless the diode is isolated from the supply like a 445, 405, or 635... (unless I'm not reading his diagram correctly)

Because with a linear driver (Jib, DDL, FlexModP3), the negative input and output are one and the same. So it's a direct connect from the negative supply to the diode.

Now if you also give a direct connect from the positive supply to the diode as that diagram shows, then it's the same as not even having a driver in there. It will by-pass the driver...
Click to expand...

Take another look at that diagram (note the pin names).

That's why his setup was particularly ingenious, it WILL work for case positive diodes, even with regulators that regulate through the positive side of the driver.

It's brilliant really, and simple. You can use a typical linear (DDL, Jib, Mohgasm,etc) to drive case positive build without isolation.
 
Hmmm...

Interesting.

So you are saying that you can just reverse the polarity in the connection with a linear driver?

Just do everything the same, except switch positive with negative?

This is new to me. Have you tried it?

Edit: Oh I see now... The circuit is connected the same. But after the diode instead of before the diode! Ingenious!

5943-neg-driver.png


This thought it new to me, and I'm still trying to wrap my head around it. One question. How about the negative input of a linear driver such as a FlexModP3 or a Jib driver? Do you have a diagram?
 
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Yeah I dont get it... Isnt that just like puting in the battery backwards! I did see that on one of the DRLAVA diagrams.
 
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Kizdawg said:
Yeah I dont get it... Isnt that just like puting in the battery backwards! I did see that on one of the DRLAVA diagrams.
Click to expand...

Nope!

In a series circuit the current is the same throughout it....so as a result it will still be the same amount of current no matter if you place the laser diode before or after the linear regulator.

With switching ones, however, this is not the case...
 
Just a little update, guys. The first set of boards was received by Clif yesterday. I expect them up for sale on his site either today or tomorrow.

Once they are up for sale, I think I may open up a legitimate advertising thread for 'em.
 
Wolfman29 said:
Just a little update, guys. The first set of boards was received by Clif yesterday. I expect them up for sale on his site either today or tomorrow.

Once they are up for sale, I think I may open up a legitimate advertising thread for 'em.
Click to expand...

I'd certainly like to try one of these boards, they must be of great quality :D
 
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The first iteration s actually not that nearly high-quality as the next batches will be. The board manufacturer screwed up the boards (or at least there was a misunderstanding on what it means to have a lower limit on trace width :P ), so a trace that was required for correct operation is missing. I jumpered the traces necessary so it is perfectly functional and the jumper did not increase the overall size of the board or ability to heatsink, but it doesn't look as pretty :P

These are going to be selling on Clif's site at a discounted price of $20 each board because it is only the V1 version. V2, requiring less heatsinking, will probably be listed on his site in the middle of next week.
 
If I'm going to heat sink this driver, which side would I thermal epoxy onto it? I'd know if it were a boost or linear, but I've never worked with a buck driver before. The round component side or the square one? Thanks in advance! Sweet new driver on the block. :beer:
 
Heatsink the side with the big square chip. Also, if you can, the resistor on the other side. The resistor shouldn't need heatsinking, but it will heat up, so if you can heatsink it, it will help total board dissipation.
 
Good news on the BlitzBuck front!

BlitzBuck V1 Round, a more efficient design, has just been successfully tested! It is capable of outputting over 2A (haven't tested higher) continuously without a duty-cycle at over 90% efficiency! With the proto-design (situated on a 16.4mm singled sided board), I am drawing 1.35A at 8.7V to output 5.2V at 2.04A! And, this is just the beginning! The next version should be capable of outputting 3A of power for those of you wanting to test the other diodes ;)

These will probably not be in Clif's shop until the middle of May, but they will be very capable.

Look forward to a V2 of the rectangular version (still approximately 75-80% efficient) in Clif's shop as well, soon!

Also... this one is continuous ground! WOOO!
 
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