I want to use lmr16006x to charge a bank of four 10.000uF capacitors. The capacitors are used for bridging power supply in case of power fail. The idea was to use the FB-Pin to set the final voltage and to use the internal peek current limit to set the charging current. I have tested it with a modified LMR16006XEVM (R4->1M5, Uout=58V) and it works - in principle.
What I do not understand is the behavior of the LMR16006 most of the time during charging the capacitors (current limit operation). It seems that the controller is operating not with the specified frequency of 700kHz but with round about 140kHz only.
- Can you explain this behavior?
- Has it something to do with not further explained section called "Frequency Shift" of the block diagram?
- How should I select the inductor in this special case?
- If I use lmr16006y instead what frequency will I get during current limit operation?
- Does operating the part in this way for a short time (<10s) cause any damage to the device?