E-elephant,
My initial thought would be NO.

For operation in this type of circuit , the capacitor normally needs
to be at least X1 rated. The alternative you're suggesting does not
appear to have this type of rating. Unfortunately most caps with the
rating and the capacitance value you need for 9mA will be physically
large.

Basically, the rating relates to the failure mode and construction of
the capacitor and is based on safety requirements if the capacitor
fails. In your specific application you may not have this requirement,
but in general, it would not pass safety inspection.

I'm also not too sure about your circuit. You appear to have a
resistor R1 in parallel with C1, while it is more normal to have a
resistor in series. It can also be useful to have a capacitor in
parallel with VD1 to act as a capacitive voltage divider and reduce
the effect of mains transients.

RP

2008/8/26 Electronic Elephant <electronic.elephant.group@gmail.com>:
> Hi,
>
> Now my case using the capacitor-divider to generate a 9mA current for
> payload.
> This circuit can work fine, but the C1(0.47uF,630V) is too big to us.
> It's volume is nearly: 29mm*13mm*20mm(height),
> [image: http://91mcu.bokee.com/inc/AC-DC.bmp]
> Now I found another capacitor on the TDK's website:
> http://www.tdk.co.jp/tefe02/e415_ckg.pdf
> Quote:
> 2-chip Piled Multilayer Ceramic Capacitors
> CKG Series CKG32K Type
> FEATURES
> =95 No polarity.
> =95 Twice the capacitance is obtainable on a single capacitor space.
> =95 Unique construction provides high reliablity.
> =95 The metal caps absorbs stress from thermal and mechanical
> shocks, ensuring excellent performance on aluminum circuit
> substrates.
> =95 Low ESR and ESL promises excellent characteristics for high
> frequency switching power supply.
> APPLICATIONS
> Smoothing circuits, temperature variable applications,
> Maintenance free power supplies, DC to DC converters, automotive
> applications.
> it seems very small.
>
> Now my problemis :Can I use it in my design to replace the orginal
> capacitor?
>
> Thanks in advance!
> --
> E-elephant
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