| Nappylady |
The problem I have with it, is that all the pins are so close together, and when PCB'ing, it's hard to make it so you can have traces "behind" the chip; this complicates the design. :scratch:
I know I've heard of some non-IC chip amps (if anyone has a link, I've searched and can't find--please show me!) that use packages that are like big power transistors, only with 8 pins instead of 2 or 3. I look at them and think, wow, that would make PCB design so much easier.
Does anyone suppose National would be willing to make some chips in this fashion instead of TO-220? Or, since we are the DIY type, could we order a few 3875 dies :D and package them ourselves? :smash:
(have a look at http://www.chelseatech.com/packages.htm - from whence I grabbed this image, and I wonder if they offer the service I'm looking for...)
(Edit - Forgot to attach the stupid image!) |
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| millwood |
opa's I think come in to3 packages.
I believe the lm chips are also avalable in die form from national. you can get the whole wafer and have a packaging plant in Taiwan to do it for you.
a couple million dollars should do I think, :) |
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| sam9 |
If you think TO-220 is triublesome in this regard try usinf TO-126! There is a crude solution to your problem -- assuming your layout software lets you do so, alter the TO-220 footprint the spread the the pads out a bit. Next, when you insert the TO-220s just spead the leads enough to match the pad spacing. Ive done this on TO-126 and find it helpful. You can even do this in a way that the leads form a rather sable tripod much like a TO-92. If you want to mount the TO-200s flat you can still do something like bend the center lead lond and the two others shorter.
Expiriment! You will find something that works for you. |
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| Nappylady |
Layout software? What's that? :D :smash:
I've done this exact thing before.... since only 5 pins connect on the 3875, you can trim 6 of 'em and respace the others... you're right, it is a crude solution, and it does help a little bit!
Wouldn't it be awesome to have a TO3 package with 5 pins though... much easier to lay out... (probably harder to heatsink, but hey! Cross that bridge when you get to it. :D ) |
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| Hybrid fourdoor |
Is this something like what your looking for?
OPA541AM High Powered BurrBrown Opamp in 8 pin T-03
The only problem I can think is how Im gonna sink these suckers....dont want to drill 8 little holes in a heatsink :bawling:
I got these as samples from TI, but I work at TI so I don't know if outsiders are limited to the 11 pin plastic package.
Also one cool thing about the 541AM is that the case is isolated from the actual circuitry, so it doesn't need any seperator sheet on the heatsink :)
-David
Ok I see that these suckers are $100 a pop at Digikey...so chances are smaples are gonna be slim :( |
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| Matttcattt |
| quote: | Originally posted by Hybrid fourdoor
Is this something like what your looking for?
OPA541AM High Powered BurrBrown Opamp in 8 pin T-03
The only problem I can think is how Im gonna sink these suckers....dont want to drill 8 little holes in a heatsink :bawling:
I got these as samples from TI, but I work at TI so I don't know if outsiders are limited to the 11 pin plastic package.
Also one cool thing about the 541AM is that the case is isolated from the actual circuitry, so it doesn't need any seperator sheet on the heatsink :)
-David
Ok I see that these suckers are $100 a pop at Digikey...so chances are smaples are gonna be slim :( |
i have got at least 9 of these from TI in sample form. i see that they have been removed from the sample program now though. :( |
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| Hybrid fourdoor |
| quote: | Originally posted by Matttcattt
i have got at least 9 of these from TI in sample form. i see that they have been removed from the sample program now though. :( |
Hmm...ya sorry, it still shows them available for me.
What about OPA501? Those anygood for audio? |
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| Circlotron |
| quote: | Originally posted by Nappylady
Layout software? What's that? :D :smash: |
Fluffy pajamas. |
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| soundNERD |
You really don't want the high power transistor style metal can case, since they aren't the easiest things to connect in the world.
What I would think is the to-220 case would be perfect, if it didn't have that row of pins in the back.
Actually, I never have problems with PCBs.
-Mike |
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| Nappylady |
Yeah, 5 pins non-staggered would be great :D
Of course, you can "kinda" get this by clipping pins and bending! :smash:
Let's petition National! |
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| neutron7 |
well you can cut off all the unused pins. then you have a lot more room on the board for example LM 3875 which only uses 5 of 11 pins there is tons more space for fat traces, feedback resistor etc, right under the chip.
i would love it if the pins were standard spaced though! |
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| Matttcattt |
| i just stuck the pins of the chips (TO-220) in my vice (gently), and all the pins got bend strait. |
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