> >> Be sure to measure Vin on the circuit side of any Iin ammeter.
> >> Be aware that high frequency power supply noise on power wiring (in
> >> and out) can play havoc with some meters). Largish cap (100 uF?)
> >> across meter terminals can help.
> =

> > Since the noise most likely is in the 100s of MHz range, a smallish cap
> perhaps
> > would be better. A ferrite clamp can also help.
> =

> As the smps oscillator typically runs in the 100's of kHz region,
> that's where the noise is.

I am talking about conducted and radiated EMI which, with the waveforms sho=
wn =

in figures 2-16 - 2-18 in the MCP1640 datasheet, will be much higher than 1=
00's =

of kHz.

Check it out with a spectrum analyzer.

The higher frequencies will most likely interfere as radiated noise with th=
e =

testleads working as an antenna.

The levels will of course be highly depending on the layout and decoupling =
of =

the circuit.

/Ruben =


=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D

-- =

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