OPA1622/VSON10 breakout board layout - diyAudio
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Old 16th May 2017, 08:27 PM   #1
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Default OPA1622/VSON10 breakout board layout

As written in my CMoy/Hello World thread I am interested in the OPA1622, which has one huge draw back for breadboard prototyping: VSON10 package with a 3x3mm (0.11"x0.11") footprint.

For the more common packages (e.g. SOIC8) adapter boards to DIP8 are available. But since there are only a few VSON10 chips available, there seems to be no commercial interest for these breakouts. To fix this, I started to design a breakout board of my own.

The VSON10 features two additional pins:
The first is a enable toggle. I routed it to an external connector, but also added a trace to V+ for "always on" (trace needs to be cut for external enable signal).
The other is a GND pin. The datasheet requests a clean, analog ground for best performance.

Having a GND connection on the board allowed me to do a ground fill (both top + bottom, but this required three vias for good results).

For best performance, the datasheet asks bypass caps to be as close to the IC as possible, thus I added spots for optional 0603 bypass caps to the board. Having spots for feedback resistors/caps on the board would also be nice (says the datasheet), but I don't think I could cramp them on there (and also, swapping 0603s for prototyping seems a tad bit too fiddly).
Also, the head dissipation plane (V-) on the back is already not that huge.

Before I build a 10x10cm grid (7x7 boards) I would like to ask opinions on the layout. This is the first time I did something like this ;-)

So do you think it's okay that way?
Or did I try too hard to prevent parallel lines?
Is the heat dissipation area big enough, or too little?


If I produce these I will probably set up a group buy. The 490 breakout boards would cost me 34US$ via dirtypcbs (or 60US$ with ENIG and quicker shipping to Europe). And I only need a few of these...

Question on producing: As I understand it, I need to put the 49 copies of my board onto a 10x10cm area and add lines for v-groove. Or is there are better/cheaper panelization option?

Some links:
OPA1622 thread on diyaudio: New Audio Op Amp - OPA1622
Datasheet: http://www.ti.com/lit/ds/symlink/opa1622.pdf
VSON10 package: http://www.ti.com/lit/ml/mpds117k/mpds117k.pdf
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Last edited by ArchimedesMP; 16th May 2017 at 08:36 PM. Reason: fix some dyslexic tendencies :P
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Old 16th May 2017, 08:50 PM   #2
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Interesting idea. A couple of suggestions if I may. I would rotate the OPA1622 by 180 degrees so that the V+ supply pin of the adapter board is closer to the corresponding OPA1622 pin. This way you can use the thermal pad to route the V- supply to the OPA1622 pin. As it is now the V+ trace is too long and this can be improved. I would also skip the enable pin connector and just add a resistor divider between V+ and GND to enable the IC once the power is ON.
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Old 16th May 2017, 08:59 PM   #3
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Also if you make the entire bottom side a copper pour connected to the OPA1622 thermal pad you will greatly improve the cooling of the IC. GND connection is only needed next to the decoupling capacitors and thus you do not need it on the bottom layer since this will have little effect on the overall GND connection impedance, IMO.
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Old 16th May 2017, 09:35 PM   #4
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I built some OPA1622-to-DIP10 adapters.

(PCB layout in post #76)


(test bench and testing results in posts #209, 210, 211)
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Old 16th May 2017, 11:31 PM   #5
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Oleg, of course you may I did a quick try at rotating the 1622 by 180 degrees, but wiring got really difficult. Sticking to the DIP8 op-amp pin out is really... not nice.

But I did change the bottom plane to be V-, and could shorten V+ a bit.
See attached image.

Maybe I could put the OPA on the bottom. This would change the geometry and might enable a nicer solution (not sure if that's good for cooling, though).
Also, this could be a hassle in scenarios where height is an issue?
Will try that later, but neither today (was listening to music far too long and should get some sleep^^) nor tomorrow (gf anniversary).

Honestly, I don't know what benefit a resistor divider on the board would offer? If you could explain it, that would be nice
According to the datasheet, Enable can just be connected straight to V+ (what I did). So the IC is up if there's power, same as with divider. Additionally, if someone would like to use the enable feature [e.g. with resistor divider instead of direct connection], it's "exported" via the pin.


Mark, oh, yes, didn't see those. Also quite nice But I want to be able to use the OPA1622 in existing circuits with DIP8 sockets. I think plutonim did that, but his layout didn't seem to be easily available.
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Old 17th May 2017, 02:20 AM   #6
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Good luck to you!
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Old 17th May 2017, 06:29 PM   #7
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I'll play with the OPA1622 DIP8 adapter and see where it leads me. I'll do it just for fun since I like designing small PCBs I don't need such adapter for myself but I'll share it here should it turn out decent.

The resistor divider for the enable pin would allow unmuting the chip when the rails are say at 80% by calculation the resistors following the design notes in the datasheet. This would possibly allow suppressing the start up glitch when the supply rails are not fully settled at start up. Just compare minimum supply voltage and enable voltage - output will be unmuted before the supply rails are operational. Since 0603 resistors are going to be used it is easy to short the pads and connect the enable pin straight to V+.
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Old 17th May 2017, 09:03 PM   #8
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Here is my attempt. Let me know if you like it and I'll post the gerbers. Pin numbers/names are for reference only. Pin one of the adapter is marked.
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Old 19th May 2017, 09:49 AM   #9
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Slightly improved layout. Reduced number of vias in signal path and increased traces width.
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Old 19th May 2017, 05:06 PM   #10
ammel68 is offline ammel68  United States
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Very nice layout Oleg.

I wished someone could supply an adapter board like yours with the OPA1622 already soldered to it, since that seems to be the big problem with trying it.
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