SMPS Design Help

Please try to quantify this.

Battery charging often tolerates (or even improves with) ripple.

What should the current do when the output sees a short circuit?

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Regards,

John Popelish

I am aware that some batteries like AC ripple; however, new chemistries (Li-Ion) and old (NiMH) do not like the ripple.

When I short circuit is seen by the charger the peak current should be

10 Amps or to the current set-point.

Thanks,

(snip)

So, how much ripple, either in peak to peak amperes or % of max current. There is a big difference in the design of a

10 amp regulator that has 1 amp, peak to peak ripple and one that has 1 mA peak to peak ripple. "Low ripple" is not a specification.

--
Regards,

John Popelish

Hello John,

On a 10 Amps of current I can accept no more than 10 mA (5 mA or less would be ideal).

Thank you,

Jon

Could you supply a battery part/type reference that justifies this ripple current limitation, while still tolerating 10A continuous charging levels?

There are not many 300-500V loads that will draw current with only a

0.1% ripple component. They may require a low supply noise level, over specific frequency bands, but that is a different issue, that could be addressed with local post-regulation, independant of the actual converter, at moderate power levels.

If this is an EMC consideration, you might specify a standard that allows larger current at the lower power conversion frequencies.

RL

Remember the battery burping chips? Now there is ripple for you.

Another thing to think about in batteries that large is periodic "equalization" charge cycles.