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One pinout to fit them all - how can it be this hard?!

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daqq:
Hi,

As most people these days, I'm searching the net for alternative parts. And seriously...

I'm looking for a DC DC step up converter, something to replace the TPS61221. There's an abundance of devices that have the same exact functionality, some with slightly different parameters (works from a higher voltage, lower/higher currents, that sort of thing). Like, there's MAX1722, LTC3525D-3.3, TPS61261, about a gazilion devices from Torex, stuff from Microchip... all battery input, +3V3 fixed output. And yeah, some have different packages, but are compatible enough that you could make a footprint that accepts more of them or even you could even hack a UQFN-6 onto an SC-70 footprint. Not pretty, but would work. If only...

The damn things have the same pins, same functions, same requirements, some even have the same packages, but different pinouts. Is this intentional or simply random? I can see one layout being optimal for EMI/EMC, but since there's an abundance of them, I'm guessing that there's no one layout to rule them all.

If there was an industry standard like there's for op amps that would ease my current headache considerably. But noooo...

Sorry, had to vent.

David

Kleinstein:

--- Quote from: daqq on February 10, 2022, 08:12:07 am ---...
If there was an industry standard like there's for op amps that would ease my current headache considerably. But noooo...

--- End quote ---
Witt SOT23-5 / SC70 size there are also different pin configurations for OPs - usually the standard one and some alternatives.  The LT1013 and a few more have a different pin-out in SO-8, supposedly because the old die and bond wires would not fit in the normal configuration.

The odd pinouts sometimes help with the layout, e.g. for a single sided PCB.

daqq:

--- Quote ---Witt SOT23-5 / SC70 size there are also different pin configurations for OPs - usually the standard one and some alternatives.
--- End quote ---
Sure, I know that there are variations. But for the most part you have the same pinout on them, with the occasional weird one. And generally the weird ones have their reason, like ultra high input impedance or shutdown pins, offset adjust etc. And sure, not every op amp will replace every op amp. But at least you have the option to swap some parts.

magic:
I guess China is the last place where anyone still cares about designing drop-in substitutes for competitor parts :D
The rest wants to lock you into their proprietary solution >:D

Besides, I'm sure it's simply a matter of "make the pinout fit the IC layout" rather than "design the IC to fit a particular pinout".
And they work that way because it's easier and because see above.

T3sl4co1l:
Shrug, SOT23-6 bucks seem to have a de facto pinout standard, but others, who knows.  I'm not so familiar with boost unfortunately.

At least the current is low enough you could probably put a few footprints side by side and not mind the strays..?  Sucks for space of course.

Tim

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