[moved] How to calculate the Oscillation for back-up Battery Supply???

[killercharger]

Hello!

I'm trying to design a Backup Battery Supply so it can be exempt from testing if it oscillates under 9kHz per the FCC Code.

Does anyone know how to calculate this given the following???

Input: 5v/500mA
Output: 5v/1A
Conversion Efficiency: >85%
3000mAh

Attached is a picture of a similar product:

 

[FvM]

Which FCC rule are you referring to? The swiched mode converter inside the battery pack will surely use a higher operation frequency than 9 kHz to fit the case with acceptable efficiency (e.g. several 100 kHz). This shouldn't be a problem with state-of-the-art power supply filtering.

On the other hand, a converter switching at 9 kHz can still involve harmonics up to MHz, e.g. generated by rectifier diodes. So it doesn't release the manufacturer from checking EMI standard compliance.