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From: legg <legg@nospam.magma.ca>
Newsgroups: sci.electronics.design
Subject: Re: neat Hall sensor
Date: Sat, 04 Jan 2025 12:07:06 -0500
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On Fri, 03 Jan 2025 08:07:49 -0800, john larkin <JL@gct.com> wrote:

>On Fri, 03 Jan 2025 09:33:01 -0500, legg <legg@nospam.magma.ca> wrote:
>
>>On Thu, 02 Jan 2025 08:09:16 -0800, john larkin <JL@gct.com> wrote:
>>
>>>On Thu, 02 Jan 2025 09:05:03 -0500, legg <legg@nospam.magma.ca> wrote:
>>>
>>>>On Tue, 31 Dec 2024 15:58:07 -0800, john larkin <jl@glen--canyon.com>
>>>>wrote:
>>>>
>>>>>
>>>>>https://www.monolithicpower.com/en/mcs1802.html?srsltid=AfmBOoq2BNuYQ-Ef5ee9o7-gyHDqRkK_xS5TAKb-MgxtjZ6r71FItxXm
>>>>>
>>>>>Really nice, as compared to a shunt and an isolated ADC and all that
>>>>>stuff. Reasonably accurate, especially above 20c.
>>>>>
>>>>>But they can't be serious about pushing 50 amps through an SO8
>>>>>package. Or not for long.
>>>>>
>>>>>Their demo board thermal design is kinda silly.
>>>>>
>>>>>
>>>>
>>>>Demo board makes sense to me. Simplest thermal conductivity 
>>>>test.
>>>
>>>They used 4 oz copper, hardly practical.
>>
>>?
>>
>>What's impractical about 4oz copper in a power circuit?
>>Are you saying it's not enough?
>
>I'm saying that you can't put any other reasonable parts on the board.
>4 Oz is fine for a demo board, but not so good for a board with 0402
>parts and FPGAs and anything that does anything but measure current.
>
>It would be interesting to get the eval board and actually push 50
>amps through it.
>
>I see a lot of data sheets with absurd power and current ratings, like
>a dpak rated for hundreds of amps and watts, with tiny footnote
>somewhere that cautions about package or lead limits. IR started the
>trend of specifying chip therortetical limits that can't be approached
>in real life, and then everybody had to tag along.
>
>>
>>I'd say it was more than could be expected from a 
>>simple demo board and is typical of higher current 
>>layout in this neck of the woods, where power and 
>>control circuits try not to share the same board or 
>>board layer. 
>
>Exactly. 
>
>>
>>Also, using a part with a 50A full scale in a 25-30A 
>>continuous rated circuit would be normal pactice, 
>>where duty cycle, crest factor or pulse/surge are 
>>anticipated under normal operating conditions. 
>>
>>There are 'better' SMD packages available, if that is your 
>>only concern. You seem to have found some.
>
>They could at least merged the high current pin pairs into big
>paddles.

Ends up looking like an automotive fuse link.

>
>It's a nice part. We're using the 10 amp version at up to 7.5 amps.
>The 50 amp version is silly.

Well, when you actually get around to using it (probably in a 
relatively remote location) be sure to R/C the power and 
data lines. R in series with source, C at receiving end.

RL