Why by-pass resistor for Inductor

drjohsmith

Joined Dec 13, 2021
397
Hello ronsimpson,
Thanks for your update.
If possible could you please share any link,where I can read about this in detail.
It does say " for optional current loop"
i.e. the resistors are by default no fit

Given the limited description,
my guess, is that the designer might have wanted to be able to optionally measure the current consumption during initial testing,
so they put in extra pads, such that they could remove the series inductor, and replace it with known small value resistors,
which they could measure voltage across and thus deduce current consumption
 

ronsimpson

Joined Oct 7, 2019
2,078
the resistors are by default no fit
No. When designing a noise filter, you do not want a high Q inductor. The filter will ring and cause noise at the resonant frequency. Also the ring may mess up the error amplifier.

allegory: My neighbor plays his music too loud. I made a very large brass bell and put it over his house. Now I only hear the bell ring all night long. Next, I made a tent of cloth and insulation and put it over his house. Now I can sleep in quiet.
 

drjohsmith

Joined Dec 13, 2021
397
No. When designing a noise filter, you do not want a high Q inductor. The filter will ring and cause noise at the resonant frequency. Also the ring may mess up the error amplifier.

allegory: My neighbor plays his music too loud. I made a very large brass bell and put it over his house. Now I only hear the bell ring all night long. Next, I made a tent of cloth and insulation and put it over his house. Now I can sleep in quiet.
@ronsimpson

The picture does show
1647962587915.png

As it says current loop
and says optional

I'd say its for measuring current during testing , not for optional filter parts,
Could be wrong,
But occams razor tends to point that way

but I guess we will never know the designers intent
 
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