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Hall Effect current pulse with 1 uS response time

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tonyctsiu

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Dear All,


I just wonder if there is any existing components which :
1. detect current pulse with 1 uS response time
2. consumes less than 1 mA
3. is small enough to be fitted into a mobile phone


Thank you and best regards,

Tony
 

Prototyp_V1.0

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Given that yo're allowed to use a very small current transformer, your request #2 doesn't make any sense. It will be connected in series to any load.
Request #3 shouldn't be a problem.
 

tonyctsiu

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Dear Mr. Prototyp_V1.0,

Many thanks for your reply.

I should have written clearly that the way I wish to detect current is to make it thru Hall effect. It is because I need an non-intrusive way of detecting current.
There seems to be many hall effect detectors around. The closest one I found is the OMNI Polar hall effect switch made by allegromicro which consumes 2mA. I haven't tested it on my application. Not sure if it can be used to detect current.
I will try it out soon.
Regards,

Tony
 

dick_freebird

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There are analog Hall sensors but they tend to be slow. The
problem I believe is that the Hall effect is very weak, so the
sensors have op amps and such wrapped around them which
of course slows things down plenty.

A current transformer (like Tek CT-1 / CT-2) has much better
transient performance, but no DC measurement capability at
all. It is not invasive in the sense that it changes circuit
resistance, but you do have to pass a wire through a hole
and that means breaking the circuit once. Some small bit
of inductance would be added to the current path.

You might find clamshell current transformers that can
be applied without breaking a connection.

Digi-Key has some Hall sensors. The ones I have used are
for tens of amps and are about 1cm x 1cm x 2cm, and you
have to solder them inline (they have a very low resistance
multi-lead path). I have seen bare Hall sensors in TO-92
transistor package form, I'm sure there are SO ones now,
but the fidelity is something that's on you - sensitive to
proximity and orientation, to the current path and any others
that may also be throwing a magnetic field nearby. You
would have to take care of calibration if you needed any
kind of accuracy.
 
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